American Water Works Association Engineering Modeling

American Water Works Association Engineering Modeling Applications Committee Hydraulic Model Calibration Subcommittee Annotated Bibliography Citation Review Template February 2014

Field No. 1 Citation ID 1962_001

Field No. 2 Citation Date

Year Month Day

1962 October 01

Field No. 3 Author

--- Last Name First Name

Primary AWWA AWWA

Secondary

Tertiary

Additional

Field No. 4 Citation Title

AWWA California Section Committee Report: Loss in Capacity of Water Mains -- JAW_0066986

Field No. 5 Citation Type

Book Reference

Conference Paper

Journal Paper

Technical Report

Presentation Manual Standard or Guideline

Video Workshop Material

X

Field No. 6 Publisher

Name American Water Works Association

Location Denver CO 80235 USA

Field No. 7 Citation Specifics

Volume Number Issue Chapter Pages

54 10 10/01/1962 1293 - 1312

Page 1 of 2

Field No. 8 Keywords | Terms

Field No. 9 Abstract

The primary objective of this article was to summarize the causes of, and to suggest remedies for, loss in carrying capacity of mains. The article discusses biological growths, silting, incrustation, and tuberculation as the most common forms of deposits that accumulate on the interior of the pipe, thus causing capacity loss in water mains. The physical, chemical, and biological characteristics of the water, and the choice of materials used for distribution system construction are discussed as factors that influence the nature and degree of deposition in pipe lines.

Field No. 10 | Optional Notes | Commentary

Field No. 11 | Optional Full Citation Format (APA, MLA, etc.)

Page 2 of 2




1 Month Day

1976 April

Field No. 3 Author


Primary Charles L. Eggener

Secondary Lawrence B. Polkowski

Tertiary

Additional


Network Models and the Impact of Modeling Assumptions


Book Reference

Conference Paper

Journal Paper

Technical Report



X






68 4 189 - 196

Page 1 of 2


Model Parameters Methodological Grid/Network Skeletonization


Network simulation expedients such as skeletonization, load consolidation, and assumed pipe resistance factors are discussed. An approach to fulfilling the research need is presented which consists of building detailed models of actual but representative grid systems, verifying the performance of the models, and using them as research tools to investigate the impact of various simplifying assumptions often made in network modeling. A case study is reviewed in detail.


Discussion of methods used to expedite model construction such as skeletonization, demand consolidation, and assumed roughness. Presents an approach to assessing the impact of these expedients Presents guidelines selecting representative systems for studying these which are simpler systems but well-gridded. All-pipes models compared with models skeletonized to various degrees Presents examples of previous guidelines for skeletonization cited in literature Model configurations were compared with each other and with actual field data using statistical analysis Discrepancies were noted between field data and all-pipes model and were attributed to typical reasons: gauge accuracy, quality of elevation data for nodes, head loss between gauge location and node location Discussed impact of pipe roughness assumptions and conducted sensitivity analyses but also noted that demand differences which are not easily measured contribute more to model error Areas noted for further study include comparing multiple scenarios for C-Value fit, better information on demand allocation, and need for more skeletonization studies.


Eggener, Charles L.; Polkowski, Lawrence B., Network Models and the Impact of Modeling Assumptions, Journal - American Water Works Association, April 1976, Volume 68, Issue 4, Page(s): 189-196

Product Number: JAW_0004847

Page 2 of 2




Year Month Day

1977 September

Field No. 3 Author


Primary Shamir Uri

Secondary Howard Charles D.D.

Tertiary

Additional


Engineering Analysis of Water-Distribution Systems


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name AWWA

Location Denver CO USA



xx xx xx 510 - 514

Page 1 of 2


Definitions Historical Overview Skeletonization


In attempt to bridge the gap between technical advancements and applications, a nonmathematical explanation of modeling for analysis of water-distribution systems.


A great simplified explanation of computer modeling and a historic overview of early water distribution modeling.


Page 2 of 2




Year Month Day

1983 October

Field No. 3 Author


Primary Walski Thomas

Secondary --- ---

Tertiary --- ---

Additional --- ---


Technique for Calibrating Network Models


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name JWRPM

Location



109 4 360 - 372

Page 1 of 2


Steady State C-factor Demand Hydrant flow test


In calibrating a water distribution system model, the model user usually adjusts pipe roughness (e.g. Hazen-Williams C-factor) or water use so that the pressures and flows predicted by the model agree with values observed in the fields. This paper presents formulas to assist the user in deciding whether to adjust C or water use and by how much. The key to using the formulas is to observe pressure in the system for at least two significantly different use rates. Such data is often collected during fire flow tests. A model is considered calibrated to the extent that it can predict the behavior of the water distribution system over a wide range of operating conditions.


The paper is the first to present a systematic approach for making model adjustments and to emphasize the importance of fire hydrant flow tests to achieve sufficient head loss to make measurements meaningful.


Page 2 of 2




Year Month Day

1983 October

Field No. 3 Author



Secondary --- ---

Tertiary --- ---

Additional --- ---


Why Calibrate Water Distribution System Models?


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Water/Engineering and Management

Location



130 11 27 - 28

Page 1 of 2


Management Data Quality


That old computer saying “garbage in, garbage out” holds for water distribution system models. These models need to be calibrated and there is no excuse for using worthless data in calibration.


The paper debunks some old excuses for not doing adequate data collection for model calibration such as “literature values are good enough”, “we don’t have any high quality pressure gages or hydrant Pitot gages” or “it takes a lot of time and costs clients a lot of money to do calibration”. The paper argues in favor of hydrant flow tests as a good way to calibrate models.


Page 2 of 2




Year Month Day

1983 September

Field No. 3 Author



Secondary --- ---

Tertiary --- ---

Additional --- ---


How Constant is the Hazen-Williams Constant?


Book Reference

Conference Paper

Journal Paper

Technical Report



X X


Name AWWA Distribution System Symposium

Location Birmingham AL USA



Page 1 of 2


C-Factor Field Study Roughness


The paper reviewed the theory behind pipe roughness calculations and demonstrated that the Hazen-Williams equation was inaccurate for rough flow at high velocity. To correct for this an equation is presented that modifies the Hazen-Williams C-factor as velocity increases for rough flow (flow with no laminar boundary layer).


It is important to know the velocity in pipes when the C-factor is measured as well as knowing whether the actual or nominal diameter is used in converting the results of the test into a C-factor value. If the velocity calculated in the model are close to or below the velocity used in the C-factor test, then there will be no error. The errors only show up when the velocity in model runs is significantly higher than the velocity in the C-factor test.


Page 2 of 2




Year Month Day

1984 April

Field No. 3 Author



Secondary --- ---

Tertiary --- ---

Additional --- ---


Application of Procedures for Testing and Evaluating Water Distribution Systems


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name US Army Corps of Engineers

Location Vicksburg MS USA



EL 84 5

Page 1 of 2


Field Test Data Quality Pressure Measurement


This report described different types of testing that could be used in evaluating existing water distribution systems. Topics ranged from pipe break analysis to data collection for model calibration to a case study on building and calibrating a model.


The most relevant sections with regard to model calibration included step by step instructions for measuring pipe roughness using the parallel hose method illustrated with the results of actual tests and a discussion of differential pressure devices to be used with Pitot gages. An example of how to calibrate a real system was presented. The importance of using this data for model calibration was also discussed.


Page 2 of 2




Year Month Day

1984 June

Field No. 3 Author



Secondary --- ---

Tertiary --- ---

Additional --- ---


The Importance of Accurate Field Data for Model Calibration


Book Reference

Conference Paper

Journal Paper

Technical Report



X X


Name American Water Works Association – Annual Conference – 1984

Location Dallas TX USA



Page 1 of 2


Data Quality C-Factor Hydrant Flow Tests


If an engineer is to have any confidence in the results of a water distribution system model, the model must be calibrated using good quality data. Techniques are available to collect the data and use the data for calibration. There is no reason to settle for guess as to C-factors, water use and boundary heads for use in the model. A model without data is worth even less than data without a model.


The paper contains a number of tips for data collections such as checking pump operating points, checking pressure reducing valve settings, checking master meters and calculating the overall water use when the model data are collected. It emphasizes that hydrant should attempt to reduce system pressure by at least 10 psi.


Page 2 of 2




Year Month Day

1984 June

Field No. 3 Author



Secondary --- ---

Tertiary --- ---

Additional --- ---


Hydrant Flow Test Results


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Journal of Hydraulic Engineering

Location



110 6 847 - 851

Page 1 of 2


Pressure Hydrant Flow Tests Flow Measurement


The traditional ISO formula for predicting hydrant flow at a given residual pressure is based on several assumptions that may not always be true, such as the assumption of an essentially flat hydraulic grade line during non-fire flow conditions. A more generally accurate equation is presented and some practical tips for interpreting the test results are given.


While hydrant flow tests are useful in model calibration, a calibrated model should be able to more accurately predict the available fire flow at some specified residual pressure since it can account for more parameters than the ISO formula.


Page 2 of 2




Year Month Day

1984 October

Field No. 3 Author


Primary Walski Thomas M.

Secondary

Tertiary

Additional


Measuring Differential Pressure Accurately in Water Distribution Systems


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Water Engineering & Management

Location



131 11 28-30

Page 1 of 2


Water Distribution Flowmeters


Pitot rods can be used to measure flow rates in pipes in the field where a permanent flow meter can be excessively costly. A Pitot rod produces a differential pressure which can be converted into a flow rate with the appropriate equations. This paper describes and inexpensive field portable manometer which can be used to measure differential pressures. In recent years, however, small portable electronic differential pressure devices have reduced the need for field manometers.



Walski, T., “Measuring differential pressure accurately in water distribution systems,” WATER/Engineering & Management. 131. 28-30 (October 1984).

Page 2 of 2




Year Month Day

1985 January

Field No. 3 Author



Secondary --- ---

Tertiary --- ---

Additional --- ---


Correction of Head Loss Measurements in Water Mains


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Journal of Transportation Engineering (Pipelines)

Location



111 1 75 - 78

Page 1 of 2


Roughness C-Factor Data Quality


One method to determine head loss is to tap into a pipe at two points and measure differential pressure. It is referred to as the parallel hose method. This works well around valves and over short distances. However, this method can involve some long hoses in distribution systems. The heating of water by the sun in these hoses can leak to misleading results. The paper shows how to account for this and discusses how to avoid the problem.


The parallel hose method can be an extremely accurate method for measuring head loss in pipes. However, in hot areas with hills the difference in temperature between the water in the hose and the water in the main can introduce errors. This paper describes methods to avoid these issues.


Page 2 of 2




Year Month Day

1985 December

Field No. 3 Author



Secondary --- ---

Tertiary --- ---

Additional --- ---


Assuring Accurate Model Calibration


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Journal of the American Water Works Association




77 12 38 - 41

Page 1 of 2


Management Flow Tests


Water distribution system models are only as good as the data with which they are calibrated. Simply comparing predicted and observed pressures during normal operation cannot ensure accuracy over a wide range of conditions. Some tips for calibration are provided.


The paper discusses different approaches to calibration and compares using the author’s “analytic” approach (see 1983 paper) with a trial-and-error approach. It also discusses the value of conducting flow tests at night when demand is low if determining C-factors is the key goal of calibration. Such an approach does not ensure that the demands are well calibrated but controlling the flow by operating hydrants has value since the effects of errors in demands are small by comparison.


Page 2 of 2




Year Month Day

1985

Field No. 3 Author



Secondary --- ---

Tertiary --- ---

Additional --- ---


Conducting and Reporting Hydrant Flow Tests


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name US Army Corps of Engineers - Waterways Experiment Station

Location Vicksburg MS USA



Page 1 of 2


Flow Measurement Pressure Field Testing Hydrant Flow Test


Provides instruction on conducting hydrant flow tests and discusses the use of the test for water distribution model calibration.


The value of hydrant flow tests for model calibration is pointed out in this video.


Page 2 of 2




Year Month Day

1986 April

Field No. 3 Author



Secondary --- ---

Tertiary --- ---

Additional --- ---


Case Study: Pipe Network Model Calibration Issues


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Journal Water Resources Planning & Management (JWRPM)

Location



112 2 238 - 249

Page 1 of 2


Flow Measurement C-Factor Field Tests


The paper illustrates that is it possible to accurately calibrate a mathematical model of a complicated water distribution system (271 nodes, 307 pipes, 9 PRV’s) if adequate and accurate data are collected. It is essential that the model be calibrated for a range of water use rates and patterns and otherwise it is possible for the model to appear to be calibrated even though it contains significant errors. For example, in this system it was possible to make the model appear calibrated for C-factors that varied by a factor of three provided that sufficient compensating errors were made in other input parameters. The key to collecting adequate data is that the head at the boundary nodes (pumps, tanks, PRV’s) be known when pressure readings are made in the system.


This paper described the calibration of what at that time was a large model with multiple pressure zones for Oneonta, NY. This was the first paper to document the interaction of calibration parameters and show that compensating errors could lead to inaccurate models if the wrong parameter is adjusted. The paper illustrated the value of hydrant flow tests in that it is difficult to use compensating errors to calibrate a model if the flows in the pipes vary significantly. This verified some of the concepts first proposed in the 1983 paper “Technique for Calibrating Network Models”.


Page 2 of 2




Year Month Day

1986 February

Field No. 3 Author



Secondary --- ---

Tertiary --- ---

Additional --- ---


Measuring Water Pressure at Fire Hydrant Outlets


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name AWWA - Opflow




12 2 4 - 5

Page 1 of 2


Hydrant Flow Tests Pressure Measurement


Article discusses the error that can occur when taking a pressure reading at a fire hydrant and shows that there will be slight error when the air is not bled from the hydrant before taking the reading. However, the error is very small, especially at high pressures.


The error only begins to be significant at very low pressures in hydrants that are located at a much higher elevation than the main.


Page 2 of 2




Year Month Day

1986 --- ---

Field No. 3 Author


Primary Ormsbee Lindell

Secondary Wood Don

Tertiary

Additional


“Explicit Pipe Network Calibration”


Book Reference

Conference Paper

Journal Paper

Technical Report



×


Name ASCE

Location Reston VA 20191 USA



112 2 1195 - 1207

Page 1 of 2


Water Distribution System Hydraulic Model Networks Calibration Head Loss


In order to improve the reliability of hydraulic network models as well as eliminate the need for trial‐and‐error calibration methods, an explicit calibration algorithm is proposed. The calibration algorithm is formulated in terms of headloss coefficients and is developed from a reformulation of the basic network equations. The basic network equations are solved explicitly for headloss adjustments to exactly meet one or more measured conditions of pressure or flow for given network loading and operating conditions. The adjustments determined in this manner are used to revise pipe roughnesses or defined concentrated head (minor) losses to meet the measured conditions. In order to demonstrate the feasibility of the approach, the developed algorithm is applied to an example network.


This is the original paper that laid out a strategy for solving for other parameters besides flows and heads for water distribution systems. The proposed methodology was later adapted for applications to model calibration by including pipe roughness and nodal demands as an additional unknown.


Ormsbee, L.E., and Wood, D.J., (1986) “Explicit Pipe Network Calibration,” ASCE Journal of Water Resources Planning and Mangement, Vol. 112 (2), pp. 166-182, Times Cited: 37.

Page 2 of 2




Year Month Day

1987 June

Field No. 3 Author



Secondary --- ---

Tertiary --- ---

Additional --- ---


Does Your Model Really Model Your System


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Public Works

Location



65 - 66

Page 1 of 2


Management Field Tests


Paper presents a series of questions that a water utility manager should ask modelers with regard to assessing the adequacy of model calibration. It emphasizes that the cost of calibration is small when compared with the decisions which will be made with the model.


Some of the questions asked in the paper include, “Was the model calibrated for a range of conditions?” and “How did the modeler know if the model is accurately calibrated?” The paper defined calibration as a two step process of 1. comparison of model and field data and 2. making the necessary adjustments until the two agreed.


Page 2 of 2




Year Month Day

1988 May

Field No. 3 Author


Primary Grayman Walter M.

Secondary Clark Robert M.

Tertiary Males Richard M.

Additional


Modeling Distribution‐System Water Quality; Dynamic Approach


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name ASCE, Journal of Water Resources Planning and Management

Location Reston VA USA



114 3 295 - 312

Page 1 of 2


Algorithms Water quality


Interest is growing in determining the quality variations that exist in drinking water distribution systems. This paper is dedicated to understanding distribution‐system quality issues and to the development of a model that will enhance this understanding. A dynamic algorithm that can be used to predict water quality variations is described in this paper. Determination of the blending of flows from separate sources, tracing of transient concentrations in the system, and establishment of a compliance monitoring system are only a few of the potential uses of such a model. The model has been implemented on a microcomputer and applied to the North Penn Water Authority distribution system, Lansdale, Pennsylvania. It shows good correspondence with observed field data.



Grayman, W., Clark, R., and Males, R. (1988). ”Modeling Distribution‐System Water Quality; Dynamic Approach.” J. Water Resour. Plann. Manage., 114(3), 295–312.

Page 2 of 2




Year Month Day

1988 May

Field No. 3 Author



Secondary --- ---

Tertiary --- ---

Additional --- ---


Equipment Needs for Field Data Collection in Support of Modeling


Book Reference

Conference Paper

Journal Paper

Technical Report



X X


Name International Conference on Computer Modeling of Water Distribution Systems

Location Lexington KY USA



65 - 81

Page 1 of 2


Field Tests Pressure Measurement Flow Measurement


For a computer model of a water distribution system to be useful, it must accurately reflect what is occurring in the real system. This paper describes the kinds of equipment necessary to do a first class job of model calibration


The paper describes the kinds of meters, gages, fittings, and safety equipment that should be assembled to collect field data for model calibration. It includes a sample check list and a form for recording hydrant flow test results.


Page 2 of 2




Year Month Day

1988 November

Field No. 3 Author



Secondary Sharp Wayne

Tertiary --- ---

Additional --- ---


Predicting Roughness in Unlined Metal Pipes


Book Reference

Conference Paper

Journal Paper

Technical Report



X






80 11 34

Page 1 of 2


Roughness Data Quality Flow Measurement


The paper examines the results of hundreds of pipe roughness tests. In general the roughness grows roughly linearly with time depending on the water quality. This results in a logarithmic decay of C-factors with a fast decay in early years gradually slowing down over time.


The steps to use this procedure involve running some head loss tests and converting the results to pipe roughness. Plot the roughness vs. age to determine the rate of growth of roughness and insert that value into the formula for predicting changes in roughness and C-factor.


Page 2 of 2




Year Month Day

1988 January

Field No. 3 Author


Primary Bhave Pramod R.

Secondary

Tertiary

Additional


Calibrating Water Distribution Network Models


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name American Society of Civil Engineers: Journal of Environmental Engineering

Location



114 1 120 - 136

Page 1 of 2


Calibration Pipe networks Water distribution

systems


Calibration of water distribution network models is necessary in predicting their behavior under different loading conditions or in planning their expansions. Of the several data used in calibration, the predicted nodal demands and the pipe resistance coefficients are the least reliable. The model user usually adjusts the pipe resistance coefficients and/or the nodal demands by trial‐and‐error procedure and achieves calibration by making the predicted nodal pressures reasonably agree with the observed nodal pressures. A systematic iterative calibration procedure that decides the required adjustments in the nodal demands and pipe resistance coefficients is developed in this paper. The procedure is also illustrated through an example network.



Pramod R. Bhave (1988). “Calibrating Water Distribution Network Models.” J. Environ. Eng. 114(1), 120-136

Page 2 of 2




Year Month Day

1988 May 12 - 13

Field No. 3 Author



Secondary Chase Donald

Tertiary

Additional


“Hydraulic Network Calibration Using Nonlinear Programming”


Book Reference

Conference Paper

Journal Paper

Technical Report



×


Name University of Kentucky

Location Lexington Kentucky



Page 1 of 2


Calibration Box Complex Constrained Optimization


This paper presents a mathematical formulation of a problem for the calibration of water distribution system models using a non gradient based non linear search algorithm (i.e. Box Complex Method). The proposed algorithm is able to handle both explicit constraints (i.e. bounds on the decision variables of pipe roughness and nodal demand) and implicit constraints (pressures and flows) without the use of gradient information. During each iteration of the algorithm, a potential set of decision variable is generated which explicitly satisfies the bound constraints. This set of values is then passed to a full simulation program (i.e. KYPIPE) for evaluation of the implicit constraints. Violations of the explicit constraints are handled by pulling the solution back into the feasible region of search by use of a simple heuristic. The algorithm is shown to be highly efficient for this type of problem and is illustrated using an actual water distribution systems.


A good discussion of the Box Complex method as applied to network calibration.


Ormsbee, L.E., and Chase, D.V., “Hydraulic Network Calibration Using Nonlinear Programming,” Proceedings, International Symposium on Computer Modeling of Water Distribution Systems, University of Kentucky, Lexington, KY, May 12-13, 1988, pp. 31-44.

Page 2 of 2




Year Month Day

1988 February

Field No. 3 Author


Primary Walski Thomas A.

Secondary Sharp Wayne W.

Tertiary Shields F. Douglas, Jr.

Additional


Predicting Internal Roughness in Water Mains


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name US Army Engineer Waterways Experiment Station

Location Vicksburg MS



Page 1 of 2



A method is presented for predicting the Hazen-Williams C-Factor for unlined metal water mains as a function of pipe age. The method has two steps: a) finding the growth/rate of internal roughness, alpha, for the water main using either historical C-factor data or water quality data; and b) using predictive equations for an estimate of a future C-factor.

The predictive equations presented in this report were derived using linear regression of some 319 data points from seven utilizes as well as values from the 1920 text entitled Hydraulic Tables, by G.S. Williams and A. Hazen.

The regression equations for C-factors as a function of pipe age have a 95-percent confidence interval of +/- 15 and a coefficient of determination (r2) of 0.87.



Walski, Thomas A., Sharp, Wayne W., and Shields, F. Douglas, Jr. 1988. “Predicting Internal Roughness in Water Mains,” Miscellaneous Paper EL-88-2, US Army Engineer Waterways Experiment Station, Vicksburg, Miss.

Page 2 of 2




Year Month Day

1989 July

Field No. 3 Author



Secondary Edwards James

Tertiary Hearne V. M.

Additional --- ---


Loss of Carrying Capacity in Pipes Carrying Softened Water with High pH


Book Reference

Conference Paper

Journal Paper

Technical Report



X X


Name ASCE - Environmental Engineering Conference

Location Austin TX USA



Page 1 of 2


Roughness C-Factor Field Tests


The increase in pipe roughness and loss of carrying capacity for water mains carrying high pH was is documented with over 20 field tests conducted in Austin, Texas. The data show a high rate of growth of pipe roughness that decreases once the utility began to add scale inhibiting chemicals to the water.


It was difficult to calibrate the model of the Austin system until the rate of scale formation in the pipes could be explained and a method to assign C-factors based on age was developed.


Page 2 of 2




Year Month Day

1989

Field No. 3 Author


Primary WRC

Secondary

Tertiary

Additional


Network Analytics – A Code of Practice, Section 2 Network Model, 2.6 Calibration


Book Reference

Conference Paper

Journal Paper

Technical Report



X X X


Name Water Research Center (WRc)

Location Swindon Frankland Road

Blagrove PO Box 85

Swindon Witshire, SN5 8YR UK



2 Network Model 2.6 Calibration

19 - 21

Page 1 of 2


Guidelines Standards Criteria Steady State EPS


This section provides specific calibration criteria guidelines for steady state calibration for both flows and pressures. Flows criteria is categorized by the ratio of the measured flow to the total system demand. Pressure criteria is statistical, ranging form +/-0.5m for 85% of the samples to 2m for all samples.



Page 2 of 2




Year Month Day

1989 --- ---

Field No. 3 Author



Secondary

Tertiary

Additional


“Implicit Pipe Network Calibration”


Book Reference

Conference Paper

Journal Paper

Technical Report



×


Name ASCE




115 4 243 - 257

Page 1 of 2


Calibration Computer Programming Network Analysis Box Complex Non Gradient


An implicit mathematical model is developed for use in calibrating hydraulic network models. The calibration model uses a nonlinear optimization algorithm along with a general network solver to adjust selected model parameters for either steady state or dynamic operating conditions. Adjustable model parameters include: pipe roughness, source grades, and nodal demands. Both a steady state and an extended period calibration example are presented.


This paper introduces the use of the Box Complex method for optimizing the calibration of water distribution networks. The method has the advantage of being able to handle both implicit and explicit constraints without the need for gradient methods or penalty functions.


Ormsbee, L.E., (1989) “Implicit Pipe Network Calibration,” ASCE Journal of Water Resources Planning and Management, Vol. 115 (4), pp. 243-257.

Page 2 of 2




Year Month Day

1990 March

Field No. 3 Author



Secondary --- ---

Tertiary --- ---

Additional --- ---


Sherlock Holmes Meets Hardy-Cross (or Model Calibration in Austin, Texas)


Book Reference

Conference Paper

Journal Paper

Technical Report



X






82 3 34 - 38

Page 1 of 2


Field Tests Management Pressure Measurement


One would think that water distribution model calibration would be a straightforward logical process. Sometimes, however, the best tool for model calibration consists of a lot of detective work, a little intuition and just a pinch of luck. Some anecdotes on model calibration in Austin, Texas illustrate this principle.


The paper describes 13 different situations that arose during the calibration of the water distribution system model in Austin. In each case, the model did not initially appear calibrated and extra work was needed to correct the model. This included such things as examining the interior of older and newer pipe, finding incorrectly closed valves, identifying valves that were not shown on maps, locating areas that were “over-skeletonized” and finding new mains that were in service but were not yet on the maps.


Page 2 of 2




Year Month Day

1990 July

Field No. 3 Author



Secondary Lutes Teresa

Tertiary --- ---

Additional --- ---


Accuracy of Hydrant Flow Tests Using a Pitot Diffuser


Book Reference

Conference Paper

Journal Paper

Technical Report



X






82 7 58 - 61

Page 1 of 2


Hydrant Flow Tests Field Tests Flow Measurement


By using a Pitot diffuser when a hydrant flow test is conducted, the damage caused by water flowing from the hydrant car be reduced. When a high degree of accuracy is desired in the discharge measurement, however, an adjustment in the method of calculating discharges from Pitot pressure measurements is required.


A Pitot works by measuring the velocity head from a flowing hydrant and converting that head into velocity and hence flow. The equation typically used for this calculation is based on the assumption that the velocity head is measured under atmospheric conditions. However, in the Pitot diffusers used in this testing, the velocity head is measured in a closed section of the diffuser such that there is static pressure. This can result in significant errors. An improved equation for converting velocity head to flow rate is provided in this paper.


Page 2 of 2




Year Month Day

1991 July

Field No. 3 Author


Primary Clark Robert

Secondary Grayman Walter

Tertiary Goodrich James

Additional Deininger Rolf


Field Testing Distribution System Water Quality Models


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Journal American Water Works Association

Location Denver CO



83 7 July 1991 67 - 75

Page 1 of 2


Water quality model tracer Tank model


This article briefly review an extensive field study by the US Environmental Protection Agency and the North Penn Water Authority, which resulted in the development of a series of models to investigate contaminant propagation in a water distribution system. The application of one such model to the exploration of contaminant movement in the distribution network of Cabool. MO, is explained. An extension of this work to a large water utility – the South Central Connecticut Regional Water Authority – is also discussed.


Calibration of a dynamic water quality model of the Cheshire system of South Central Connecticut Regional Water Authority using a fluoride tracer study is described. A statistical comparison was made between the observed and modeled fluoride results. Adjustments were made in the tank module used in the model in order to improve the model results.


Clark, R.M., Grayman, W.M., Goodrich, J.A., Deininger, A.F. Hess, A.F.. 1991. "Field Testing Distribution System Water Quality Models", J.AWWA, Vol. 83, No. 7, pp 67-75.

Page 2 of 2




Year Month Day

1991 February

Field No. 3 Author


Primary Goodrich James A.

Secondary Grayman Walter M.

Tertiary Clark Robert M.

Additional


Modeling in the planning and evaluation of a field study of water quality in a distribution system


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Water Quality Modeling in Distribution Systems. AwwaRF, EPA

Location Cincinnati OH USA



Page 1 of 2


Water quality Tracer studies


None published.


Reviews the results of an extensive field study in the Cheshire service area of the South Central Connecticut Regional Water Authority. A fluoride tracer study was used in the calibration and validation of a dynamic hydraulic and water quality model of the system.


Goodrich, J.A., Grayman, W., and Clark, R.M. (1991). ” Modeling in the planning and evaluation of a field study of water quality in a distribution system”. Proc. Water Quality Modeling in Distribution Systems. AwwaRF, EPA. Cincinnati, OH. PP 201-218.

Page 2 of 2




Year Month Day

1991 April 14 - 17

Field No. 3 Author



Secondary Males Richard M.


Additional


The Effects of Skeletonization in Distribution System Modeling


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name AWWA Computers in the Water Industry – AWWA Computer Conference




661 - 684

Page 1 of 2


Skeletonization Fireflow analysis Chlorine Water age


None published


Four levels of skeletonization of the Cheshire service area (Connecticut) were modeled to assess the impacts of skeletonization on results. The following metrics were used in evaluating the results: velocity, fireflow, pressure, chlorine residual, and water age. The results indicate that an important component in the skeletonization process is intelligent engineering judgment and that the impacts of skeletonization depend upon the type of analysis being performed.


Grayman, W., Males, R., and Clark, R., (1991). ” The Effects of Skeletonization in Distribution System Modeling”. Proc. AWWA Computer Conf., Houston, TX.114(3), 661-684.

Page 2 of 2




Year Month Day

1991 February 5

Field No. 3 Author


Primary Murphy Peter

Secondary

Tertiary

Additional


Prediction and Validation in Water Distribution Modeling


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Proceedings from AWWARF/EPA conference on water quality modeling in

distribution systems, 4–5 Feb, 1991

Location Cincinnati OH 45202 USA



447 - 465

Page 1 of 2


Hydraulic model Water quality Validation Fluoride Tracer

NETWK


The testing of public water supplies near suspicious chemical releases has led to the discovery of contaminated wells in Woburn, Massachusetts and San Jose, California. Epidemiologists in both states have investigated the health effects on those who might have been affected by the water from the problem wells. In each of these cases, the problem wells were only a few of many wells in the water supply systems. Therefore, the distribution of the water from the various wells was analyzed by the author to determine the amount of contaminated water supplied to the different residential areas of those systems.

The goal of the two water system analyses is the determination of the concentrations of each of the hazardous chemicals in the water delivered to individual residences during the periods of the contamination incidents. First, the history of the concentration of the chemicals at the problem wells is determined by the study of the movement of the chemicals in the groundwater, independently of the pipe network studies. The distribution from the water from those wells is then examined using pipe network analysis to determine the concentration of the chemicals in the water delivered to the residences. The result is an approximation to the ideal description of the exposure to the chemicals.

The error level of the risk assessment model is important in evaluating the validity of the connection between chemical exposure and health effects. A part of each water distribution study reports the evaluation of the validity of the model. The evaluations are done by using the models to predict the spatial distributions of the concentrations of the fluoride ion in each water system, and then measuring the concentrations in water samples obtained during a field test of the predictions. This paper describes these accuracy level evaluations.


This paper begins with in-depth discussion behind the calculations of the hydraulic model (NETWK from Ch2M Hill) that was used for this study. The study report that the model can predict the fluoride tracer mixture concentrations with an average error of 10%.


Page 2 of 2




Year Month Day

1991 --- ---

Field No. 3 Author


Primary Boulos Paul

Secondary Ormsbee Lindell

Tertiary

Additional


“Explicit Network Calibration for Multiple Loading Conditions”


Book Reference

Conference Paper

Journal Paper

Technical Report



×


Name Routledge: Taylor and Francis Group

Location Abingdon Oxfordshire OX14 4RN UK



8 3 153 - 160

Page 1 of 2


Water Distribution Network Analysis Calibration


A semi-analytical methodology has been developed for use in calibrating hydraulic network models under multiple demand loading conditions. The resulting algorithm is able to correlate the observed and predicted pressures through the use of global head loss adjustment factors. The proposed algorithm is shown to be computationally efficient and guaranteed to yield a converged solution in an expeditious manner.


This paper extends the original explicit calibration method to multiple loading conditions, thereby increasing the theoretical accuracy of the calibration.


Boulos, P., and Ormsbee, L. (1991) “Explicit Network Calibration for Multiple Loading conditions,” Civil Engineering Systems, Vol. 8 (3), pp. 153-160, Times cited: 9.

Page 2 of 2




Year Month Day

1991 Feb 4-5

Field No. 3 Author


Primary Hunt William

Secondary Kroon Joseph

Tertiary

Additional


Model Calibration for Chlorine Residuals in Distribution Systems


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name AWWARF and EPA




237 - 263

Page 1 of 2


chlorine model calibration


This paper describes one of the earliest studies for applying a model to predict chlorine residuals in a large system. The work was performed in the Saltonstall system in Connecticut. The model did a very good job in predicting residuals at most locations although the agreement was poor at some. They found decay coefficients to be on the order of 0.025/day. They found that reservoirs caused the most significant decay of chlorine.


Paper was published in Proceedings Water Quality Modeling in Distribution Systems


Hunt, W.A. and Krron, J.R., “Model Calibration for Chlorine Residuals in Distribution Systems”, in Proceedings Water Quality Modeling in Distribution Systems, 4-5 Feb 1991, Cincinnati, Oh., US EPA and AWWA-RF.

Page 2 of 2

American Water Works Association Engineering Modeling Applications Committee Hydraulic Model Calibration Subcommittee Annotated Bibliography Citation Review Template April 2014



Year Month Day

1991 July

Field No. 3 Author


Primary Kennedy Mark S.

Secondary Sarikelle Simsek

Tertiary Suravallop Khis

Additional


Calibrating Hydraulic Analyses of Distribution Systems Using Fluoride Tracer Studies


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Journal AWWA




83 7 54 - 59

Page 1 of 2


Calibration Travel-time Tracer Study Water Quality Fluoride


Accurate predictions of pipe velocities by hydraulic models are critical to enable modeling of water quality in distribution systems. Procedures are presented for verifying pipe velocities with travel-time studies using fluoride as a conservative tracer. Results of a field study indicate that intermittent operation of fluoridation equipment is a relatively simple and effective way to determine travel times within a distribution system. These travel times can then be used to calibrate hydraulic models with respect to water demands and usage patterns.



Page 2 of 2




Year Month Day

1991 May 20 - 22

Field No. 3 Author


Primary Boulos Paul


Tertiary

Additional


“A Comprehensive Algorithm for Network Calibration”


Book Reference

Conference Paper

Journal Paper

Technical Report



×


Name ASCE




Page 1 of 2


Water Distribution Systems

Pipes Roughness Coefficients Calibration

Networks Algorithms


An explicit calibration algorithm is proposed which provides the direct and rapid adjustment of the pipe roughness coefficients and junction node demands that exactly meet a specified set of field observations of pressure or grade at designated test nodes throughout the distribution network under multiple demand loadings and corresponding network operating conditions. Both the individual pipe roughness coefficients and the junction demands are adjusted using a set of global parameter adjustment factors. The resulting algorithm is both fast and efficient and guaranteed to yield a mathematically consistent solution.


One of the first attempts to recast the pipe network equations to solve for additional parameters in additional to flow. Additional parameters included pipe roughness and nodal demands, both of which can be adjusted to help calibrate the model.


Boulos, P., and Ormsbee, L., “A Comprehensive Algorithm for Network Calibration”, Proceedings of the 18th Annual Conference of the ASCE Water Resources Planning and Management Division, New Orleans, LA, May 20-22, 1991, pp. 949-953.

Page 2 of 2




Year Month Day

1992 April

Field No. 3 Author


Primary Cruickshank Jeffrey R.

Secondary Long Steven J.

Tertiary

Additional


Calibrating Computer Models of Distribution Systems


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name AWWA – Computer Conference

Location Nashville TN USA



Page 1 of 2


Calibration Distribution Systems Field measurements Compensating errors Steady state

Hydraulic gradients


This paper addresses the issue of compensating errors by reviewing the assumptions tested when calibrating a distribution system model including roughness coefficients, skeletonization, pump performance, and demand loading. Incremental approaches to calibrating a model are reviewed, including simplifications to more clearly identify discrepancies and using graphical hydraulic gradients to calibrate. Several typical problems to avoid with respect to field data are discussed and four case studies are reviewed.



Page 2 of 2




Year Month Day

1992 April 12 - 15

Field No. 3 Author


Primary Wood Don

Secondary Lingireddy Srinivasa

Tertiary Ormsbee Lindell

Additional


“Explicit Calculation of Pipe Network Parameters for Time Varying Conditions”


Book Reference

Conference Paper

Journal Paper

Technical Report



×


Name AWWA




Page 1 of 2


Water Distribution System Pipe Network Algorithm


An explicit algorithm is presented for determining various design, operating, and calibration parameters required to satisfy a user specified set of time varying pressure conditions. The developed algorithm uses an iterative solution of an augmented set of hydraulic network equations to obtain an exact solution of the associated network parameters. The algorithm can be used by engineers to obtain exact designs of network components or the associated operating policies for pumps, valves, etc., for time varying conditions. The basic theory of the algorithm as well as several example applications of the algorithm will be presented.


The paper extends the explicit calibration methodology from static to multiple loading conditions.


Wood, D.J., Lingireddy, S., and Ormsbee, L.E., “Explicit Calculation of Pipe Network Parameters for Time Varying Conditions,” Proceedings of the 1992 computer Conference, American Water Works Association, April 12-15, 1992, Nashville, Tennessee.

Page 2 of 2




1 Month Day

1993 July

Field No. 3 Author


Primary Schulte Andreas M.

Secondary Malm Arthur P.

Tertiary

Additional


Integrating Hydraulic Modeling and SCADA Systems for System Planning and Control


Book Reference

Conference Paper

Journal Paper

Technical Report



X






85 7 62 - 66

Page 1 of 2


Data Collection SCADA Real-Time Integration


The DuPage Water Commission (DWC) of Elmhurst, Illinois, has built a new water distribution network and is monitoring it using an integrated supervisory control and data acquisition (SCADA) simulator (ISS). The ISS integrates DWC's SCADA system and its hydraulic simulator to confirm system design, develop operational scenarios, and train operators to respond to emergencies. Operations personnel have already verified the accuracy of the hydraulic simulator, which enabled them to resolve an operational problem involving a low-pressure system response. The ISS has been demonstrated for initial system studies, for verification of the transfer mechanism, and for actual storage management studies during unexpected drought strains on the system in the summer of 1992. Emergency training through return of data from the simulator to the SCADA system has been delayed. The training will enable an operator to simulate a main break, for example, and practice alternative responses by manipulating a system of remotely controlled isolation valves. Using the ISS, operators can become familiar with unusual conditions before they occur in the real system. This article presents a case study.


Early implementation of real-time modeling by linking SCADA with hydraulic model (or simulator) System is used for planning and operational studies Plans to use simulator for emergency planning Live transfer of data from SCADA system to model Discussed steps to follow to export data from SCADA and process it for use in model

Discussed key issues: data storage, Future plans for chlorine simulation


Schulte, Andreas M.; Malm, Arthur P., Integrating Hydraulic Modeling and SCADA Systems for System Planning and Control, Journal - American Water Works Association, July 1993, Volume 85, Issue 7, Page(s): 62-66

Product Number: JAW_0034228

Page 2 of 2




Year Month Day

1994 July

Field No. 3 Author



Secondary O’Farrell Shaun

Tertiary --- ---

Additional --- ---


Instrumenting Transmission Mains for Head Loss Testing


Book Reference

Conference Paper

Journal Paper

Technical Report



X






86 7 62 - 66

Page 1 of 2


Flow Measurement Pressure Measurement Field Tests


Accurately measuring head loss in large diameter transmission mains is difficult and is therefore seldom done at all. However, if a section of transmission main is installed with provisions for measuring flow and head loss, the testing can be done easily and accurately, allowing better monitoring of long-term trends in pipe roughness and carrying capacity.


When a transmission main is installed, it is less expensive to install flow and head metering equipment than to try to install it at a later time. The suggested equipment and testing procedures are described in this paper.


Page 2 of 2




Year Month Day

1995 April

Field No. 3 Author



Secondary --- ---

Tertiary --- ---

Additional --- ---


Standards for Model Calibration


Book Reference

Conference Paper

Journal Paper

Technical Report



X X


Name AWWA Computer Conference

Location Norfolk VA USA



55 - 64

Page 1 of 2


Standards Management


Paper discussed calibration standards and highlights the fact that different levels of calibration measured with different indicators are needed for different modeling applications. It also argues for calibration of models over a wide range of conditions.


This is one of the earliest papers on model calibration standards and it first describes some of the concepts found in the AWWA Engineering Computer Applications Committee journal paper on defining model calibration in 2013.


Page 2 of 2




Year Month Day

1995

Field No. 3 Author


Primary Savic Dragan

Secondary Walters Godfrey

Tertiary

Additional


Genetic Algorithm Techniques for Calibrating Network Models


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Centre for Systems and Control Engineering – University of Exeter

Location Exeter EX4 4QF Devon UK



95 12 1 - 41

Page 1 of 2


Network Analysis Genetic Algorithms Optimization Field Measurements Minimization

Error Sensitivity Probability Pipe Material Roughness


Computer models for analysing pipe flows and pressures in water distribution networks are in widespread use throughout the world as essential tools for the efficient operation and improvement of very complex systems. Models invariably incorporate a number of unknown parameters, the values of which must be chosen so that the modeled performance matches as closely as possible that of the real network. The process of calibration involves both expensive data collection and a complex parameter optimization problem. This report presents novel Genetic Algorithm based parameter calibration procedures developed to match hydraulic model output with observed data sets.


Provides a solid theoretical overview. Concepts are reinforced with a case study example from the UK (Danes Castle Zone, Exeter City).


Page 2 of 2




Year Month Day

1995

Field No. 3 Author


Primary Cesario Lee

Secondary

Tertiary

Additional


Modeling, Analysis and Design of Water Distribution Systems


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name AWWA

Location Denver



Page 1 of 2



This book contains a chapter on Model Calibration. It discuss basic concepts and the purpose for calibration. It then gives a seven step process for model calibration. It discusses the sources of errors and model acceptance.


This contains good practical advice


Page 2 of 2




Year Month Day

1996

Field No. 3 Author



Secondary Draus Steven

Tertiary --- ---

Additional --- ---


Predicting Water Quality Changes during Flushing


Book Reference

Conference Paper

Journal Paper

Technical Report



X X


Name AWWA – Annual Conference – 1996

Location Toronto Ontario Canada



121 - 129

Page 1 of 2


Water Quality EPS Chlorine


The paper demonstrates the use of a water quality model to predict water quality during flushing in a real system. The key input to calibrate the model was an estimate of the initial chlorine and initial turbidity through the system at the beginning of flushing.


While the model could be calibrated to match chlorine concentrations, and to a limited extent, turbidity concentrations, it showed that the effects of flushing would die-off after a few weeks because of the limited water use in this system.


Page 2 of 2




Year Month Day

1996 June 24

Field No. 3 Author


Primary Cesario A. Lee

Secondary Kroon Joseph R.

Tertiary Grayman Walter

Additional Wright Glyn


New Perspectives on Calibration of Treated Water Distribution System Models


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name American Water Works Association – Annual Conference

Location Toronto Ontario Canada



Page 1 of 2


Water quality


Calibrations of treated water system models is necessary to establish a credible tool that can be used for a variety of purposes. With more and more utilities developing an using models of their treated water distribution system and an ever increasing availability of computerized source data, there is a renewed interest in the implications of the term and what it really means. Models are created for a variety of purposes including planning, operations and training which require somewhat different definitions and degrees of accuracy. Purpose and differences in these types of models will be discussed. Data and accuracy of calibration in North America and in the United Kingdom will be compared. Calibration of ahydraulic model and water quality model will be described and discussed.



Cesario, A.L., Kroon, J.R., Grayman, W., and Wright, G. (1996). ” New Perspectives on Calibration of Treated Water Distribution System Models”. Proc. AWWA Annual Conference. Toronto, ON.

Page 2 of 2




Year Month Day

1997 November

Field No. 3 Author


Primary Rossman Lewis A.

Secondary

Tertiary

Additional


When Has a Model Been Sufficiently Calibrated and Tested to Be Put to Efficient Use?


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name American Society of Civil Engineers – Journal of Environmental Engineering




123 11 1070 - 1071

Page 1 of 2


Criteria Model acceptance testing Model error


None publish


In this “Forum” paper the author philosophizes about various issues relative to model calibration. Primary emphasis is on the use of model acceptance testing and criteria as a mechanism for determining how much calibration is sufficient. He identifies two general schools of thought regarding model acceptability: Universalists who believe that developing general acceptance criteria is useful, and Relativists who claim that general acceptance criteria are meaningless. Regardless if one sides with the Universalists or Relativists, the author suggests the following three ideas: (1) Collecting performance data on past applications to use for bench-marking the predictive capabilities of a class of models is a good idea; (2) More attention should be paid to explicitly representing a model’s predict uncertainty in its output and in decision making based on the model; and (3) Modeling projects should incorporate testing and acceptance criteria into a set of model quality objectives. In summary, the author states that “Because models are never perfect, their use will always require some leap of faith to trust in their predictions. The lingering question, then, is how far is one willing to leap.”

In a January 1998 discussion of the paper in the same journal, T.M. Walski emphasizes that when discussing the acceptability of model calibration it is important to distinguish between the roles of the modeler and the decision maker.


Rossman, L. (1997). ”Environmental Engineering Forum: When Has a Model Been Sufficiently Calibrated and Tested to Be Put to Efficient Use?.” ASCE. J. Environ. Eng., 123(11), 1070–1071.

Page 2 of 2




Year Month Day

1997 February

Field No. 3 Author




Tertiary

Additional


Calibration of Hydraulic Network Models


Book Reference

Conference Paper

Journal Paper

Technical Report



X






89 2 42 - 50

Page 1 of 2


Optimization Roughness Sensitivity Analysis Micro-calibration Parameter Adjustment

Data Quality Demand Allocation Macro-calibration Parameter Estimation Hydrant Flow Test


Model validity depends largely on the accuracy of input data. Once the network and initial model inputs are entered into the model, seven steps should be followed to calibrate the model: 1) Identify the intended use of the model, 2) Determine initial estimates of the model parameters, 3) Collect calibration data, 4) Evaluate the model results, 5) Perform the macro-level calibration, 6) Perform the sensitivity analysis, and 7) Perform the micro-level calibration.

The first step is determining if the model will be used for master planning, operations, or water quality and if it will be a steady-state (SS) or extended period simulation (EPS). These factors change the need for specific field data to calibrate the model with. The second step is using book or field estimated values to enter initial pipe roughness coefficients and nodal demands into the model. Pipe roughness coefficients can be estimated using the parallel-pipe or two-gage hydrant flow test methods. This step also involves the spatial and temporal allocation of demand to the model using accepted methods depending on model use. The third step is collecting the required field data for model calibration while recognizing the impact of measurement errors in that field data in connection with comparing it to model results. Collecting fire flow tests, telemetry (SCADA) data, and water quality data for model calibration are summarized. The fourth step is evaluating the initial model results against fire hydrant tests and other field collected data. Model accuracy criteria should be carefully set up based on the intended model use, type of simulation (SS or EPS) and system-specific variances. This step involves understanding the factors in both the model and the field data that can cause variations between the two.

The fifth step is performing a macro-level model calibration to confirm model inputs with systematic evaluation. This is completed to determine if any of the inputs are incorrect causing a large difference in measured versus modeled values. After macro-level calibration, the sixth step to perform a sensitivity analysis is useful in determining the most likely source of model error. Global or pressure-zone wide adjustments to roughness coefficients and/or model demands can determine their relative impact on model results. The results of the sensitivity analysis can help determine which parameters have the most impact on the model results and therefore have the most need to fine tune. The seventh, and last step, is micro-level model calibration. This includes adjusting input parameters for smaller areas of the system and getting the EPS model results to match the available telemetry (SCADA) data as well. This is mostly a trial and error approach; however, at the time, automatic calibration of network models was started to emerge as an available calibration technique.

The final topic discussed is two analytical approaches for reducing the number of unknowns in the model calibration process. The simulation approach is used for solving for one or more calibration factors through the addition of one or more network equations. The downside to this approach is that only one unknown can be tested at a time. The optimization approach is establishing the calibration problem as a nonlinear optimization problem consisting of a nonlinear objection subject to linear and nonlinear equality and inequality constraints such as pressure and/or flowrate. Variables are then adjusted by the model software to get establish the model parameters best as possible to remain with a certain threshold of the constraints. General and genetic optimization offer powerful algorithms for use in calibration a water distribution model but can result in invalid values if boundary conditions are not correct. It is expected that future developments and applications of GIS and SCADA technology, as well as optimal sampling algorithms will lead to even more efficient tools.


This journal article is a great place for a beginner to start to understand the model calibration process and determine its basic steps. Equations are good for more advanced users to refresh their memory on the equations the model is performing and the overall sensitivity of model inputs to model results. Steps for performing hydrant flow tests both for estimating roughness calculations and obtaining calibration data are helpful as this is not always completed correctly in the field or with the right pressure/flow measuring equipment. The telemetry (SCADA) and water quality data field data collection sections were a bit light on what really should be collected for what type of model use and the common pitfalls of those data sources in regards to calibration. The analytical approaches section seems a bit out of place and could confuse readers as there is little introduction to why they are included in this publication.


Ormsbee, L, and Lingireddy, S., "Calibrating Hydraulic Network Models,” Journal of the American Water Works Association, Vol 89, No. 2, February 1997, pp 42-50.

Page 2 of 2




Year Month Day

1998

Field No. 3 Author



Secondary

Tertiary

Additional


Use of tracer studies in water quality models to calibrate a network hydraulic model


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Essential Hydraulics & Hydrology – Haestad Press

Location Waterbury CT 06708 USA



Section 1 I-3 to I-8

Page 1 of 2


Tracer studies Fluoride


Tracer studies and water quality models have been used in many applications as part of the calibration process of hydraulic models of hydraulic models of small and medium sized distribution systems. To date, the tracer studies have involved manual collection and analysis of the samples. In order to increase the practicality of the method and to extend it to larger systems, development of inexpensive, automated monitors is required. The technology exists for such monitors but increased user demand is needed to encourage packaging of a low-cost field unit.



Grayman, W.M. (2012). “Use of tracer studies in water quality models to calibrate a network hydraulic model”. In Essential Hydraulics & Hydrology. Edited by A. Strafaci. Haestad Press. Waterbury, CT.

Page 2 of 2




Year Month Day

1998 November/December

Field No. 3 Author


Primary Bush Cheryl A.

Secondary Uber James G.

Tertiary

Additional


Sampling Design Methods for Water Distribution Model Calibration


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name American Society of Civil Engineers: Journal of Water Resources Planning and Management

Location



124 6 November/December 334 - 344

Page 1 of 2


Calibration Models Parameters Pressure measurement Sampling

Sensitivity analysis Water distribution

systems


Field sampling is sometimes performed to support modeling activities—specifically, to estimate the parameters of a mathematical model or, more accurately, to calibrate the model. In this case, a relevant question for field sampling design is “how to maximize the confidence in estimated parameter values, given a level of sampling effort?” We approach this question using established ideas in parameter estimation and sampling design theory, and propose general sensitivity-based methods to rank the locations and types of measurements for estimating the parameters of a water distribution network model. The proposed methods are suboptimal, yet practical, and are applied to select good tracer and pressure measurement locations for estimating pipe roughness coefficients. These particular results suggest that, when compared to pressure measurements, tracer measurements can be informative for calibrating network hydraulic parameters, but one must take more care in selecting their location. Using the proposed methods, a selection of both tracer and pressure measurements improves estimation confidence by a factor of 2, over that obtained using tracer or pressure measurements alone.



Sampling Design Methods for Water Distribution Model Calibration

by Cheryl A. Bush, (Cincinnati Water Works, Engrg. Div., 4747 Spring Grove Ave., Cincinnati, OH 45232; formerly, Grad. Res. Asst., Dept. of Civ. and Envir. Engrg., Univ. of Cincinnati, Cincinnati, OH 45221) and James G. Uber, (corresponding author), (Assoc. Prof., Dept. of Civ. and Envir. Engrg., P.O. Box 210071, Univ. of Cincinnati, Cincinnati, OH 45221-0071 E-mail: [email protected])

Journal of Water Resources Planning and Management, Vol. 124, No. 6, November/December 1998, pp. 334-344, (doi: http://dx.doi.org/10.1061/(ASCE)0733-9496(1998)124:6(334))

Page 2 of 2




Year Month Day

1998 --- ---

Field No. 3 Author


Primary Lingireddy Srinivasa


Tertiary

Additional


“Neural Networks in Optimal Calibration of Water Distribution Systems”


Book Reference

Conference Paper

Journal Paper

Technical Report



×


Name ASCE




3

Page 1 of 2


Neural Networks Water Distribution

Systems


Artificial neural networks are being used increasingly for several civil engineering applications. However, a majority of those applications have been limited to perform interpretation and classification of incomplete and noisy data. This paper presents an optimization model based on genetic algorithms which uses a neural network model for function evaluation in conjunction with a rigorous mathematical simulation model. Genetic optimization, while being robust and efficient in obtaining a near global optimal solution compared to conventional nonlinear optimization approaches, requires a large number of function evaluations. However, it can tolerate approximate function evaluation with little or no loss of efficiency in obtaining a near global optimal solution. In this context, the use of a trained neural network in place of a simulation model can significantly increase the computational efficiency of the optimization model. This is true, however, only when the training phase of the neural network does not require excessive computational time. The present study employs an efficient training scheme which greatly reduces the training period compared to the popular back-propagation scheme. Although the proposed optimization framework can be applied to several civil engineering problems, the present study focuses on calibration of water distribution systems in particular.



Lingireddy, S., and Ormsbee, L., “Neural Networks in Optimal Calibration of Water Distribution Systems,” Artificial neural Networks for Civil Engineers: Advance Features and Applications, ASCE, 1998, 227 pp.

Page 2 of 2




Year Month Day

1999

Field No. 3 Author


Primary Howie Douglas C.

Secondary

Tertiary

Additional


Problems with SCADA Data for Calibration of Hydraulic Models


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name 1999 American Society of Civil Engineers – Annual Water Resources Planning and Management Conference

Location Tempe AZ 85281 USA



1-8

Page 1 of 2


Hydraulic models Calibration Water distribution

systems Water supply Data collection


When calibrating a hydraulic model, more field information may not be better. The volume of information available from SCADA systems that collect flow and pressure information within a distribution system may be more than a modeler would prefer. Problems such as timing of data collection, inconsistent data (i.e. hydraulic grades indicate flow in one direction with metered data indicating flow in the other), and the difficulty in identifying whether a set of changes to the data makes for a better calibration begin to appear as the amount of data increases. This paper discusses several of these problems and identifies how they can be overcome. Examples from a project where SCADA was used in calibration will be used to illustrate various points.



Howie, D. (1999) Problems with SCADA Data for Calibration of Hydraulic Models. WRPMD’99: pp. 1-8. Doi: 10.1061/40430(1999)35

Page 2 of 2




Year Month Day

1999 April

Field No. 3 Author


Primary AWWA Engineering Computer Applications

Committee

Secondary

Tertiary

Additional


Calibration Guidelines for Water Distribution System Modeling


Book Reference

Conference Paper

Journal Paper

Technical Report



X






Page 1 of 2


Guidelines Elevation Assignment Sampling Error Measurement Error Criteria

Roughness Demand Allocation Water Quality Data Quality Connectivity


The purpose of this paper is to present guidelines for network model calibration. The degree of accuracy needed for model calibration should be developed in context with the intended use of the model. The paper discusses calibration approaches and testing procedures that can be used to aid in the calibration effort. The issue of when is the model calibrated well enough for its intended use is addressed. Various sources of error in model calibration including errors in input data (nominal versus outside model diameters, etc.), unknown internal pipe roughness values, effect of system demands, errors in system maps (as-builts, GIS), node elevations (ground versus actual depth and field measurement elevations), effect of time (flow and pressure variations daily and seasonal), model detail (skeletonized systems), geometric anomalies (connectivity, valve status), outdated pump characteristics curves (numerical vs. actual pump curve fit, impeller wear), and poorly calibrated measuring equipment (including SCADA measuring points).

The paper contains a short discussion on the increased level of effort and requirement for accurate data for water quality model calibration. Calibration methods are discussed including trial-and-error and direct solution techniques or optimization approaches. There is a discussion and comparison between US vs. UK calibration acceptable levels of calibration. Calibration accuracy targets for models depending on their use 1) Planning, 2) Design, 3) Operations, and 4) Water Quality is discussed and outlined in a table. Six calibration criteria have been identified with minimum goals for each. The criteria are level of detail, type of simulation, number of pressure readings, accuracy of pressure readings, number of flow readings, and accuracy of flow readings.


This paper has good discussion on sources of model error. However, it is a little light on the calibration methods and level of accuracy targets discussion. The premise of when is a model calibrated enough is not covered in enough detail.


AWWA Engineering Computer Applications Committee. (1999). "Calibration guidelines for water distribution system modeling." Proceedings of the 1999 AWWA Information Management and Technology Conference (IMTech), New Orleans, Louisiana, April 1999.

Page 2 of 2




Year Month Day

1999 August 01

Field No. 3 Author


Primary Greco Massmio

Secondary Del Giudice Giuseppe

Tertiary

Additional


New Approach to Water Distribution Network Calibration


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Journal of hydraulic Engineering, ASCE

Location Reston Virginia USA



125 8 8 849 - 854

Page 1 of 2


Calibration LINDO Nonlinear programming optimization Quadratic Programming

Water distribution Networks



A new approach is proposed for calibrating hydraulic network models. This procedure uses a nonlinear optimization algorithm along with a standard, off-the-shelf, network solver. Pipe roughness is adjusted until simulation results agree with the values observed in the field. To achieve realistic calibrated roughness values, the objective is to minimize the sum of the squares of the differences between the calibrated and initial pipe roughness estimates, under a set of constraints determined from a sensitivity matrix. The algorithm is applied to a sample network, and the resulting calibrated network is tested under different loading conditions.


Pipe roughness is adjusted using NLP model to match simulation results with the values of pipe roughness observed in the field. The sum of the squares of the differences between the calibrated and initial pipe roughness estimates was minimized.


Greco, M. and Giudice, G. (1999). ”New Approach to Water Distribution Network Calibration.” J. Hydraul. Eng., 125(8), 849–854.

Page 2 of 2




Year Month Day

1999 June 8 - 11

Field No. 3 Author




Tertiary

Additional


Optimal Network Calibration Model Based on Genetic Algorithms


Book Reference

Conference Paper

Journal Paper

Technical Report



×


Name ASCE




Page 1 of 2


Water Distribution Hydraulic Models Calibration Computer models Optimization models


The validity of a hydraulic network model depends not only on the accuracy of its physical and geometric data but also on the accuracy of certain parametric data such as pipe roughness coefficients and nodal demands. Difficulties associated with economical and reliable measurements for these parameters often dictate estimation of these parameters through model calibration. This paper describes an optimization approach to calibrate a network model for demand adjustment factors in the context of an extended period analysis. The proposed model obtains an optimal solution by minimizing a nonlinear objective function subject to a set of linear and nonlinear constraints using a powerful search technique based on a genetic algorithm. Application of the optimal calibration model on an example water distribution system demonstrates the efficiency of the proposed approach.



Lingireddy, S., and Ormsbee, L., “Optimal Calibration Model for Water Distribution Systems,” Annual Conference on Water Resources Planning and Management, Phoenix, Arizona, June 8-11, 1999.

Page 2 of 2




Year Month Day

1999

Field No. 3 Author


Primary Ormsbee Lindell E.


Tertiary

Additional


Calibration of Hydraulic Network Models


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name McGraw-Hill Professional

Location New York City New York 10020 USA



14 1 - 23

Page 1 of 2


Optimization Roughness Sensitivity Analysis Micro-calibration Parameter Adjustment

Data Quality Demand Allocation Macro-calibration Parameter Estimation Hydrant Flow Test


Model validity depends largely on the accuracy of input data. Once the network and initial model inputs are entered into the model, seven steps should be followed to calibrate the model: 1) Identify the intended use of the model, 2) Determine initial estimates of the model parameters, 3) Collect calibration data, 4) Evaluate the model results, 5) Perform the macro-level calibration, 6) Perform the sensitivity analysis, and 7) Perform the micro-level calibration.

The first step is determining if the model will be used for master planning, operations, or water quality and if it will be a steady-state (SS) or extended period simulation (EPS). These factors change the need for specific field data to calibrate the model with. The second step is using book or field estimated values to enter initial pipe roughness coefficients and nodal demands into the model. Pipe roughness coefficients can be estimated using the parallel-pipe or two-gage hydrant flow test methods. This step also involves the spatial and temporal allocation of demand to the model using accepted methods depending on model use. The third step is collecting the required field data for model calibration while recognizing the impact of measurement errors in that field data in connection with comparing it to model results. Collecting fire flow tests, telemetry (SCADA) data, and water quality data for model calibration are summarized. The fourth step is evaluating the initial model results against fire hydrant tests and other field collected data. Model accuracy criteria should be carefully set up based on the intended model use, type of simulation (SS or EPS) and system-specific variances. This step involves understanding the factors in both the model and the field data that can cause variations between the two.

The fifth step is performing a macro-level model calibration to confirm model inputs with systematic evaluation. This is completed to determine if any of the inputs are incorrect causing a large difference in measured versus modeled values. After macro-level calibration, the sixth step to perform a sensitivity analysis is useful in determining the most likely source of model error. Global or pressure-zone wide adjustments to roughness coefficients and/or model demands can determine their relative impact on model results. The results of the sensitivity analysis can help determine which parameters have the most impact on the model results and therefore have the most need to fine tune. The seventh, and last step, is micro-level model calibration. This includes adjusting input parameters for smaller areas of the system and getting the EPS model results to match the available telemetry (SCADA) data as well. This is mostly a trial and error approach; however, at the time, automatic calibration of network models was started to emerge as an available calibration technique.

The final topic discussed is two analytical approaches for reducing the number of unknowns in the model calibration process. The simulation approach is used for solving for one or more calibration factors through the addition of one or more network equations. The downside to this approach is that only one unknown can be tested at a time. The optimization approach is establishing the calibration problem as a nonlinear optimization problem consisting of a nonlinear objection subject to linear and nonlinear equality and inequality constraints such as pressure and/or flowrate. Variables are then adjusted by the model software to get establish the model parameters best as possible to remain with a certain threshold of the constraints. General and genetic optimization offer powerful algorithms for use in calibration a water distribution model but can result in invalid values if boundary conditions are not correct. It is expected that future developments and applications of GIS and SCADA technology, as well as optimal sampling algorithms will lead to even more efficient tools.


This chapter is almost an exact repeat of the 1997 AWWA Journal Article "Calibrating Hydraulic Network Models,” Vol. 89, No. 2, February 1997, pp 42-50. This version has some slight rewording and added graphics on spatial allocation of demand; otherwise it is very much the same content.

This book chapter is a great place for a beginner to start to understand the model calibration process and determine its basic steps. Equations are good for more advanced users to refresh their memory on the equations the model is performing and the overall sensitivity of model inputs to model results. Steps for performing hydrant flow tests both for estimating roughness calculations and obtaining calibration data are helpful as this is not always completed correctly in the field or with the right pressure/flow measuring equipment. The telemetry (SCADA) and water quality data field data collection sections were a bit light on what really should be collected for what type of model use and the common pitfalls of those data sources in regards to calibration. The analytical approaches section seems a bit out of place and could confuse readers as there is little introduction to why they are included in this publication.


Ormsbee, L.E., and Lingireddy, S. "Chapter 14 – Calibration of Hydraulic Network Models," Water Distribution System Handbook, Ed. L. W. Mays, McGraw-Hill Press, New York, NY, Chapter 14, pp 1-23, 1999.

Page 2 of 2




Year Month Day

2000 August

Field No. 3 Author



Secondary Rhee Houjung

Tertiary

Additional


Assessment of Skeletonization in Network Models


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Water Quality Modeling in Distribution Systems. AwwaRF, EPA

Location Minneapolis MN USA



Page 1 of 2


Skeletonization


Skeletonization is the process of representing a water distribution system by selected pipes. Historically, skeletonization was the norm and was dictated by limitations of the computer models or the resources available to develop the network representation. With the advent of more powerful models and data handling techniques, skeletonization is no longer essential but becomes a trade-off between the potentially greater accuracy that can be achieved with more detailed networks and the costs associated with data gathering, network building, output analysis and longer computer run times associated with the more detailed representations. In this paper, accuracy, use, cost, parameterization, and calibration issues associated with skeletonization are discussed. A case study is presented in which four different levels of skeletonization are modeled.



Grayman, W.M. and Rhee, H. (2000). Assessment of Skeletonization in Network Models, Proc. Joint Conf. on Water Resources Eng. and Water Res. Planning and Manage., ASCE. Reston, VA, 2000.

Page 2 of 2




Year Month Day

2000 June

Field No. 3 Author


Primary Ancel S.

Secondary Chase D.

Tertiary Cruickshank J.

Additional Walski

Grayman T. W.


Water Distribution Model Calibration – The key to Good Decision Making


Book Reference

Conference Paper

Journal Paper

Technical Report



X X


Name American Water Works Association – ACE 2000 – Workshop 1




Page 1 of 2


Data Collection Optimization Tracer Studies Standards Guidelines

Water Quality



The notes from this AWWA Sunday workshop contain a collection of presentations on model calibration prepared by the speakers for. The topics covered data collection, use of calibration data, steps in calibration, optimization applied to calibration, water quality, use of tracer studies and calibration standards. Many of the papers included had been presented/published elsewhere and were reprinted with permission for these notes. The workshop was organized by the Engineering Computer Applications Committee.


Page 2 of 2




Year Month Day

2000 January

Field No. 3 Author



Secondary --- ---

Tertiary --- ---

Additional --- ---


Model Calibration Data: the Good, the Bad and the Useless


Book Reference

Conference Paper

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X






92 1 94 - 99

Page 1 of 2


Field Tests Data Quality Pressure Measurement


Water distribution system models are used to simulate a variety of conditions, including extreme flow events such as maximum hour demands and fire flows. Some models are tested only under average demand conditions, in which head loss is commonly of the same order of magnitude as errors in head loss measurements. Data collected when the head loss is small in comparison with errors in measurement may give false impression that the model is calibrated. Substantial errors may exist in the model that will not become apparent until the model is used at a time when the head loss and velocity are high. This article contains guidelines for collecting data so that the model calibration will be meaningful.


While utilities collect a great deal of data on water distribution system status, much of it is collected at times when the hydraulic grade line is so flat that errors in measurement are significant. Such data are only useful in model calibration for the purpose of checking boundary heads and ground elevations. They do not provide any insight into flows or pipe roughness since the effect of velocity on head loss cannot be determined accurately. The paper also encourages modelers to base comparisons between model and field conditions in hydraulic grade line units rather than pressure units.


Page 2 of 2




Year Month Day

2000 August

Field No. 3 Author



Secondary Lowry Steve

Tertiary Rhee Houjung

Additional --- ---


Pitfalls in Calibrating an EPS Model


Book Reference

Conference Paper

Journal Paper

Technical Report



X X


Name ASCE EWRI Conference

Location Minneapolis MN USA



Page 1 of 2


EPS Model Demand Allocation


Creating diurnal demand curves should be a fairly straightforward process using tank water level and flow meter data to reconstruct demands. However, there are frequently problems with the raw data and how those raw data are used. This paper discusses some of those problems and how they can be avoided.


The basic concept in developing a diurnal demand is a simple flow balance. However, actually developing such a curve, given imperfect data, can be challenging.


Page 2 of 2




Year Month Day

2000

Field No. 3 Author


Primary Ainola Leo

Secondary Koppel Tiit

Tertiary Tiiter Kalle

Additional Vassiljev Anatoli


Water Network Model Calibration Based on Grouping Pipes with Similar Leakage and Roughness Estimates


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name American Society of Civil Engineers




NA NA 1 - 9

Page 1 of 2


Leakage Calibration Roughness Grouping Linear optimization


A simple integrated approach to calibration of water network model and leakage distribution is proposed. The distribution of water losses is studied as the first step in the calibration procedure of the mathematical model. In order to calculate the leakage from pipe an empirical formula which takes into account the length of the pipe and mean pressure, and also contains certain coefficients, is used. For determination of leakage the pressure measured in control nodes is used. For defining pressure in other nodes an iteration process is applied which determines the leakage and pressure intermittently. Following that process the roughness values of the pipes are varied to minimize the differences between the calculated and measured pressures. Pipes with almost similar roughness are grouped together and corrections of roughness for each group are set up. This is followed by adjusting roughnesses with linear optimization process, where the increments of roughnesses are determined on condition that the sum of the squares of the differences between the simulated and measured pressure in control nodes will be minimal. A trial-and-error approach has been used for the comparison as well. The method was used by elaborating a software package for water distribution network of the City of Tallinn.


A heuristic attempt for calibration through pipes grouping taking leakage into consideration.


Ainola, L., Koppel, T., Tiiter, K., and Vassiljev, A. (2000) Water Network Model Calibration Based on Grouping Pipes with Similar Leakage and Roughness Estimates. Building Partnerships: pp. 1-9. doi: 10.1061/40517(2000)197

Page 2 of 2




Year Month Day

2000 February

Field No. 3 Author


Primary De Schaetzen W.

Secondary Walters G.

Tertiary Savic D.

Additional


Optimal Sampling Design for Model Calibration Using Shortest Path, Genetic, and Entropy Algorithms


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Urban Water - Elsevier

Location UK



? 2 141 - 152

Page 1 of 2


Water Dist System Sampling Design Field Measurements Genetic Algorithm Shortest Path

Entropy Method Roughness Convergence Coverage Rate Parameter Adjustment


Before hydraulic network models are to be used for predictive purposes with any degree of confidence, they need to be calibrated against field data. The selection of field test locations in a water distribution system for collection of data for such calibration, also called sampling design, is often done by subjective judgment. While providing adequate data and calibration in many applications such approaches do not ensure optimal or near optimal data collection and parameter estimation. There is therefore merit in establishing more objective and rational criteria for determining the most appropriate placement of monitoring points. Three different sampling design methods applied to selecting pressure monitoring point locations for estimating pipe roughness coefficients are presented in this paper. The first two methods rank the sampling locations based on shortest path algorithms logic. The third sampling design method attempts to identify the optimal set of monitoring points by maximizing the Shannon entropy function using a genetic algorithm (GA) search method. Results of application of the different sampling design methods to an example network are presented and a comparison made with a sampling system designed by an expert.


This citation offers a sound explanation of the optimization approaches to model calibration. Genetics algorithm, shortest path, and entropy concepts are discussed. The citation also offers a sampling design flowchart to aid in the selection of the best calibration approach/method. The concepts introduced/presented are reinforced with a case example.


Page 2 of 2




Year Month Day

2001 April

Field No. 3 Author


Primary Lansey K.E.

Secondary El-Shorbagy W.

Tertiary Ahmed I.

Additional Araujo Haan

J. C.T.


Calibration Assessment and Data Collection for Water Distribution Networks


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Journal of Hydraulic Engineering

Location



127 270 - 279

Page 1 of 2


calibration Parameter estimation Calibration assessment Data collection design


Calibration of a water distribution network is intended to develop a model that mimics field conditions under a range of demand distributions. In this paper, a three-step calibration procedure is developed that considers the uncertainties in measurement and estimation and provides a measure of the quality of the calibration. The approach can also be used to identify preferable conditions for data collection. The procedure’s steps are parameter estimation, calibration assessment, and data collection design. Parameter estimation considers input uncertainty and the resulting uncertainty in model parameters. Calibration assessment analyzes the propagation of the parameter errors on model predictions. The trace of the covariance matrix of the predictive heads is used to measure the model uncertainty. Based on this uncertainty and using a sensitivity-based heuristic analysis, data collection experiments can be designed for system-wide tests and critical pipes for individual pipe tests.

A hypothetical example is considered with results that demonstrated the overall methodology and the assessment measure behaves as expected.



Page 2 of 2




Year Month Day

2001 April – June

Field No. 3 Author



Secondary --- ---

Tertiary --- ---

Additional --- ---


Understanding the Adjustments for Water Distribution System Model Calibration


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Conference Paper

Journal Paper

Technical Report



X


Name Journal of Indian Water Works Association

Location



33 2 151 - 157

Page 1 of 2


Roughness Field Testing Pressure Measurement


The paper describes the model calibration process and makes the point that it is important to understand why adjustments are being made to the model. Assuming, for example, that all error is due to pipe roughness can lead to a model that may look calibrated but would be wrong.


The paper contains a case study illustrating steps in model calibration and illustrates the use of some equations for determining the parameters to adjust and the magnitude of adjustment.


Page 2 of 2




Year Month Day

2001 February

Field No. 3 Author


Primary Whitmore Ray

Secondary

Tertiary

Additional


Is the Time Right for a Consensus on Model Calibration Guidance?


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Journal of Environmental Engineering




127 2 February 2001 95 - 96

Page 1 of 2


Model Watershed Water quality TMDL Calibration

Hydrologic Pollutant


The traditional water quality approach that has guided U.S. water protection since the mid-20th Century is based upon a philosophy of minimum degradation that equitably matches a waterbody’s assimilative capacity with pollutant loadings (Whittemore 2000). Such determinations have historically relied upon water quality models to provide the scientific basis for waste load allocations. A new science has evolved surrounding this model development. Conferences, such as the recently completed Watershed 2000 (WEF and BC Water and Wastes Association 2000), which convened in July 2000 in Vancouver, have publicized the evolving problems related to modeling credibility in the TMDL domain. This essay is a call-to-action for modeling professionals and summarizes recent e-mail exchanges among a group of experienced water quality and hydrologic modelers that address the question, When is a model calibration good enough? A relevant corollary question (not asked) was, Is good modeling calibration practice currently being applied in present TMDL development? These include academic, regulatory, and consulting modelers, but was not intended to represent an exhaustive cross section of the professional community.


This editorial is focused on sewer modeling in relation to the Total Maximum Daily Load (TMDL) programs being implemented within the US in the early 2000s. The author makes a case for the need for better guidance for model calibration that can somewhat relate to EMAC’s current initiative. Most of the article discusses watershed modeling of pollutants with no mention of water distribution modeling.


Page 2 of 2




Year Month Day

2001 April

Field No. 3 Author


Primary Bean Thomas K.

Secondary Faro Robert C.

Tertiary Walski Thomas M.

Additional


Field data collection for water model calibration, Gwinnet County, Georgia


Book Reference

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Journal Paper

Technical Report



X






Page 1 of 2


Calibration Field data collection Gwinnett County, Georgia Finished water Pressure zones

Transmission mains SCADA Flow measurements Pressure measurements Hydraulic grade line

C-values GIS Demand


This document is a presentation made at the 2011 American Water Works Association’s Information Management Conference, held in Atlanta, Georgia. Presentation documents field data gathering for flow and pressure data for calibrating a hydraulic model for the Gwinnett County, Georgia, water distribution system. System hydraulic appurtenances and field data collection approaches are described. Several references on model calibration are provided at the end of the presentation.


This presentation is a good case study of conducting a field study to gather flow and pressure data for use with calibrating the Gwinnett County, Georgia water distribution system hydraulic model.


Bean, T.K., Faro, R.C., and Walski, T.M., “Field data collection for water model calibration,” In: Proceedings, American Water Works Association 2001 Information Management Conference, Atlanta, Georgia, 2001.

Page 2 of 2




Year Month Day

2001 April

Field No. 3 Author



Secondary Widderich, Kevin J.

Tertiary

Additional


Comparing Skeletonized and Detailed Hydraulic Models


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name AWWA – IMTech

Location Atlanta, GA GA USA



Page 1 of 2


Calibration Skeletonized Field tests Water Quality Chlorine Decay

Fire flow Friction loss Trunk mains


This paper compares flow, pressure and water quality predictions from a skeletonized model to the results from a highly detailed model of the same system. Both models used the same software to model the water distribution system of Burlington, North Carolina. Both models used data from extensive field tests, and both were calibrated with field measurements. Water quality simulations used the same decay coefficients. The skeletonized model had approximately 450 pipes including all pipes 12-inches and larger, plus some of the 8-inch pipes. Demand was distributed to about 130 nodes. The detailed model was built from an AutoCAD drawing that included every pipe in the system. This model had approximately 3,500 pipes including 2-inch pipes and intricate connections at intersections. This model distributed demand to approximately 2,100 nodes. The paper compares predicted fire flows at several locations. Predicted pressures are compared for maximum hour demand, the design condition. Water quality predictions are compared at several locations, including sampling points where grab sample measurements were available. The paper discusses each model’s advantages and disadvantages and provides insight into differences in predicted results and the level of effort required to build, maintain and interpret results from each type of model.



Page 2 of 2




Year Month Day

2001 June 01

Field No. 3 Author


Primary Akel Tony A.

Secondary

Tertiary

Additional


Best Practices for Calibrating Water Distribution Hydraulic Models


Book Reference

Conference Paper

Journal Paper

Technical Report



X X



Location



10

Page 1 of 2



Hydraulic network analysis is a powerful tool used in many aspects of water distribution planning, design, operation, management, emergency response, system reliability analysis, fire flow capacity evaluation, and water quality simulations. With advances in hydraulic modeling software and the abundance of user-friendly features, constructing hydraulic models has become simpler than ever. Furthermore, recent built-in calibration and optimization tools can further simplify the calibration process. In addition to the powerful software tools, a variety of user skills are required for successfully constructing and calibrating water distribution hydraulic models. This paper discusses the best practices, applicable to most modeling approaches, which enhance the integrity and quality of assembled hydraulic water models. Though most practices are technical in nature, some focus on the usually overlooked yet highly effective people skills. Includes 6 references, tables, and figures.



Page 2 of 2




Year Month Day

2002

Field No. 3 Author


Primary Wu Zheng Y.

Secondary Walski Thomas

Tertiary Mankowski Robert

Additional

Herrin Gurrieri Tryby

Hartell

Gregg Robert

Michael Wayne


Impact of Measurement Errors on Optimal Calibration of Water Distribution Models


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Technology, Automation and Control of Water and Wastewater Systems (IFAC)

Location Gdansk Poland



Page 1 of 2


Water Dist System Modeling Optimization


A comprehensive approach is presented for the calibration of hydraulic network models, which can effectively handle any combination of the model parameters such as pipe roughness, junction demand and link (pipes, valves and pumps) operational status. A case study is demonstrated to investigate the impact of the field measurements on the optimal calibration. Optimal calibration runs of different combinations of model parameters are also conducted by using the field measurement with different accuracy. It shows that a model may appear calibrated by adjusting one type of parameters, even if that is not the correct parameter to adjust. The sensitivity of the different types of model parameters is analyzed for the calibration accuracy.


The results show that the calibration errors can result from measurement errors and also by the compensation of different parameters such as pipe roughness or junction demands. The study further demonstrates that the proposed calibration approach is able to cover the real calibration scenarios.


Page 2 of 2




Year Month Day

2002 January

Field No. 3 Author


Primary Akel Tony

Secondary

Tertiary

Additional


Establishing the Data Confidence Index


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Conference Paper

Journal Paper

Technical Report



X


Name 2002 AWWA IMTECH Conference

Location Kansas City MO USA



Page 1 of 2


Hydraulic model Index Confidence Geospatial Data Quality


Establishing an index for each geospatial entity, or utility component in hydraulic modeling, will provide a benchmark for monitoring the individual and overall integrity of the data. It then becomes easier to focus on enhancing the quality of the weakest components (elements with the lower index) to improve the overall data quality. This paper introduces the Data Confidence Index (DCI) and recommends establishing and using it to enhance the quality and integrity of the geospatial data. Includes 4 references, tables, figures.



Page 2 of 2




Year Month Day

2002 --- ---

Field No. 3 Author




Tertiary

Additional


“Hydraulic Network Calibration Using Genetic Optimization”


Book Reference

Conference Paper

Journal Paper

Technical Report



×


Name Routledge: Taylor and Francis Group

Location Abingdon Oxfordshire OX14 4RN UK



19 1 13 - 39

Page 1 of 2


Calibration Hydraulic Network Water Distribution Genetic Algorithm Nonlinear Optimization


The validity of a hydraulic network model depends not only on the accuracy of its physical and geometric data but also on the accuracy of certain parametric data such as pipe roughness coefficients and nodal demands. Difficulties associated with economical and reliable measurements for these parameters often dictate estimation of these parameters through model calibration. This paper describes an optimization approach to calibrate a network model for pipe roughness coefficients, and spatial as well as temporal demand adjustment factors. The proposed model obtains an optimal solution by minimizing nonlinear objective function subject to a set of linear and nonlinear constraints using a powerful search technique based on a genetic algorithm. Application of the optimal calibration model to water distribution systems using synthetic calibration data demonstrates capabilities of the proposed algorithm to generate good solutions in an efficient and robust manner.


This paper describes the use of a genetic algorithm in calibrating a water distribution system. One of the inherent problems using GAs has to do with the proper selection of penalty functions when explicit constraints are placed on the decision variables.


Lingireddy, S., and Ormsbee, L., (2002) “Hydraulic Network Calibration using Genetic Optimization,” Civil and Environmental Engineering Systems, Vol. 19 (1), pp. 13-39, Times Cited: 6.

Page 2 of 2




Year Month Day

2003

Field No. 3 Author



Secondary Chase Donald

Tertiary Savic Dragan

Additional Grayman Beckwith

Kolle

Walter Stephan

Edmundo


Advanced Water Distribution Modeling and Management


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Bentley Systems

Location Exton PA USA



Page 1 of 2


Field Testing Data Quality Roughness


This book is a comprehensive textbook on water distribution modeling. The calibration related sections lead the reader through the entire calibration process including chapters on system testing, SCADA systems and calibration for a variety of types of models from steady state to water quality.



Page 2 of 2




Year Month Day

2003 May

Field No. 3 Author


Primary Kapelan Zoran

Secondary Savic Dragan

Tertiary Walters Godfrey

Additional


A Hybrid Inverse Transient Model for Leakage Detection and Roughness Calibration in Pipe Networks


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Technical Report



X


Name Journal of Hydraulic Research

Location



41 5 481 - 492

Page 1 of 2


Network Leak Detection Genetic Algorithm Hybrid Optimization Levenberg-Marquardt Constraints

Optimization Network Analysis Pipe Roughness Inverse Transient Model Flow Measurement


Leakage detection and calibration of hydraulic models are important issues for the management of water and other distribution networks. An inverse transient model based on a hybrid search technique is presented here. The inverse model is developed mainly for the detection of leaks in water distribution networks. The inverse transient procedure is formulated as a constrained optimisation problem of weighted least-squares type. Two optimisation techniques are tested: the genetic algorithm (GA) and the Levenberg–Marquardt (LM) method. After examining their performance, a new hybrid genetic algorithm (HGA) is developed to exploit the advantages of combining the two methods. The resulting HGA-based inverse transient model is compared with the GA and LM-based inverse transient models using two case studies. The HGA-based inverse transient model proved to be more stable than the LM-based model and it is more accurate and much faster than the GA-based inverse transient model.


This citation covers the development of a hybrid method of model calibration for leak detection. The main concepts introduced and discussed are reinforced by two case studies.


Page 2 of 2




Year Month Day

2004

Field No. 3 Author


Primary Hatcher Mark D.


Tertiary Smith Charlotte D.

Additional Mann Mary Ann


Monitoring and Modeling of the Sweetwater Authority Distribution System to Assess Water Quality


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Conference Paper

Journal Paper

Technical Report



X


Name AWWA Annual Conference




Page 1 of 2


Validation Tracer test


As part of a study of nitrification in the Sweetwater Authority (SWA) distribution system, a unique monitoring and modeling program was carried out to characterize the movement, transformation and mixing of water in the distribution system and in distribution system tanks and reservoirs. The monitoring and modeling program was composed of the following primary tasks: an innovative tracer study, which did not require injection of a tracer chemical, in order to characterize movement through the distribution system; validation of the SWA network model using tracer study results; application of a network model to understand water quality dynamics in the distribution system; measuring the vertical distribution of temperatures in several tanks over a period of weeks in order to evaluate potential stratification; and, modeling tank mixing and aging.



Hatcher, M.; Grayman, W.M, Smith C.D., Mann, M.A. (2004). Monitoring and Modeling of the Sweetwater Authority Distribution System to Assess Water Quality. Proceedings, AWWA ACE.

Page 2 of 2




Year Month Day

2004 November -

Field No. 3 Author


Primary Engineering Computer Applications

Committee

Secondary Distribution Modeling Subcommittee

Tertiary

Additional


M32 Computer Modeling of Water Distribution Systems, Second Edition


Book Reference

Conference Paper

Journal Paper

Technical Report



X



Location Denver Colorado 80235 USA



M32 Second Edition

Page 1 of 2


Guidelines Data Quality Genetic Algorithm Steady-State Extended Period

C-Factor Parameter Adjustment Water Quality Accuracy Criteria


In context to collecting data for model development regarding network, operational, and demand conditions, page 32 of the book discusses collecting data for model calibration to determine how well the model represents and predicts the performance of the actual system. A calibration goal of 5-10 percent of observed performance is mentioned. Field data collection for calibration is split into two phases: physical data and operational data. The book suggests collection of physical data when demands are low and operational data when demands at their highest. Alternatively high-demand conditions can be created by conducting fire flow tests for collection operational data.

Page 56 discusses model calibration for steady-state simulations. Calibration can involve trial-and-error as well as optimization techniques using genetic algorithms. Fine-tuning a model in a steady-state scenario should include checking for known errors and not going outside normal limits for inputs (e.g. C-factors of 25 are indicative of another issue such as a closed valve). Field conditions for steady-state simulations should include both flow and HGL comparisons. Checking several conditions is good practice. Acceptable limits of accuracy depend on how a model is used. Each input has a limited range of adjustment and some inputs affect others.

Page 109 discusses model calibration for extended period simulations. This section repeats what calibration is and what parameters it can involve. Criteria should be established for each specific model; there are no universally accepted criteria. Criteria can be established from qualitative methods based on visual inspection of observed and model results or quantitative comparison utilizing statistical tests of observed and model results. Qualitative criteria are often based on visual review of time series plot comparison of results. This section repeats many of the points on calibration techniques in the steady-state simulation section.

Starting on page 149 in Appendix A, four questions were asked to utilities about their model calibration. The majority of respondents indicated that they used consultants to complete their model calibration and that the most recent calibration was completed within the last four years. A fair number of utilities did not know how accurate their model was or how frequency it was calibrated. Page 152 in Appendix A discusses water quality calibration questions asked from utilities. A quarter of utilities who responded complete water quality models with most using historical data or field surveys to calibrate them.


In the pages covered in the abstract, there is not a whole lot of detail on how to perform a calibration or when a model can be considered calibrated. It gives a good introduction to calibration but does not cover critical details of completing steady-state and extended period model calibration. The discussion on calibration in this book tends to repeat itself between steady-state and extended period simulation sections.


American Water Works Association. "M32 Computer Modeling of Water Distribution Systems, Second Edition." Denver, CO, November 2004 pp 32, 56, 109, Appendix A, 2004.

Page 2 of 2




Year Month Day

2004 June

Field No. 3 Author



Secondary Wu Zheng

Tertiary Hartell Wayne

Additional --- ---


Performance of Automated Calibration for Water Distribution Systems


Book Reference

Conference Paper

Journal Paper

Technical Report



X X


Name ASCE EWRI Conference

Location Salt Lake City UT USA



Page 1 of 2


Optimization Pressure Measurement Field Testing


Use of optimization to calibrate a water distribution model has been the subject of considerable research. Such models have not been systematically studied on realistic sized systems to any great extent. This paper presents an evaluation of Darwin Calibrator, a genetic algorithm approach to achieving optimal calibration. It shows that the Calibrator works well when given a sufficient amount of quality data and examines the relationship between the quality of the data and the quality of results.


In general the Darwin Calibrator was able to determine good values for roughness and demands. However, the user must keep in mind these issues when using the Calibrator:

1. There must be a reasonably large number of observations, 2. Observations must have head loss significantly greater than error in measurement in head loss, 3. The modeler must adjust the correct parameter, 4. The Calibrator works best when a reasonable range of values for the unknowns is given.


Page 2 of 2




Year Month Day

2004 March

Field No. 3 Author


Primary Van Bloemen Waanders Bart

Secondary

Tertiary

Additional


Application of Optimization Methods to Calibration of Water Distribution Systems


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Sandia Corporation

Location Albuquerque NM USA



1 - 10

Page 1 of 2


Water Dist System Network Analysis Optimization Field Measurements Pipe Roughness

Uncertainty Parameter Adjustment Tracer Methods Deterministic Methods EPANET


Inversion algorithms are used to calibrate demands of water distribution systems by minimizing the difference between observed and predicted chemical concentration values. A systematic approach was implemented using a combination of numerical experimentation, parameter studies, global methods, and local gradient based algorithms. An appropriate finite difference step was determined to calculate objective function gradients for the inversion problem. The inversion of demands for a model calibration using field tracer observations resulted in a 26% reduction of the objective function. As a result of the inversion problem, an error in the numerical model was identified that could be responsible for some of the remaining mismatch. Future work includes improving the numerical model and developing more accurate history of concentration observations. Optimization under uncertainty strategies are proposed to help characterize variability in the model calibration problem.


This citation provides a comprehensive discussion of calibration theory as framed as an optimization problem. Several calibration / optimization methods are discussed and reinforced with a few case illustration (deterministic, gradient-based, tracer-based, optimization under uncertainty, etc.).


Page 2 of 2




Year Month Day

2004

Field No. 3 Author


Primary Powell James

Secondary Clement Jonathan

Tertiary Brandt Malcolm

Additional Casey Holt

LeChevallier

Rob David Mark


Predictive Models for Water Quality in Distribution Systems


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name AWWA Research Foundation




5 Chapters 106 Total

Page 1 of 2


Water Quality Model Calibration Reaction Kinetics Hydraulics EPS

Steady State Network Analysis Parameter Adjustment Model Error Tracer Studies


From the Introduction (Chapter 1):

The objectives of the project are to characterize the current state of predictive distribution system water quality models and identify critical research needs for their improvement. The scope of the project includes both the development and application of models. The report is intended to both steer future research and act as a general reference on water quality modeling.

The project was based around a workshop which evaluated the research needs and developed the research briefs. The workshop brought together delegates with expertise in microbiology, water chemistry, and hydraulic modeling. This enabled the cross-fertilization of ideas and the development of a complimentary research agenda. Hence, the report draws from the expertise and opinions of water company practitioners, academics, and consultants with a broad range of water quality, operational, and modeling expertise.



Page 2 of 2




Year Month Day

2004

Field No. 3 Author


Primary Boccelli D.L.

Secondary Shang F.

Tertiary Uber J.G.

Additional

Orcevic Moll

Hooper Maslia

Sautner Blount

Cardinali

A. D. S. M. J. B. F.


Tracer tests for Network Model Calibration


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name World Water and Environmental Resources Congress

Location Salt Lake City Utah USA



1

Page 1 of 2


calibration Field study tracer Residence time Travel path


Typical distribution system network model calibration approaches adjust roughness coefficient values to match observed pressure and supervisory control and data acquisition SCADA data assuming known user demands. Pressure data alone, however, do not contain information related to hydraulic residence time and travel path, making such data less useful for calibrating both the hydraulic and water quality portions of a distribution system network model. This study presented a network-wide dual-tracer field-scale study, coupled with water quality monitoring, to collect a rich data set for evaluating hydraulic and water quality issues. The raw data illustrate the path-specific information that can be generated beyond the use of pressure measurements alone. The observed data are used to minimally calibrate a distribution system model that is provided by the utility, and illustrates the use of tracer data for providing confidence with respect to the predictive ability of the network model. Additional considerations related to automated calibration techniques and the potential benefits of more accurate distribution system models were discussed.



Page 2 of 2




Year Month Day

2004 June - July 27 - 1

Field No. 3 Author


Primary Davidson J.

Secondary Bouchart F.

Tertiary

Additional


A New Versatile Technique for Hydraulic Models of Water Distribution Networks


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name World Water and Environmental Resources Congress 2004, ASCE

Location Salt Lake City Utah USA



1 - 10

Page 1 of 2


Analysis Calibration Hydraulic Solver Water distribution

networks Water Distribution System


This paper presents the Unified Hydraulic Solver, a single algorithm that can perform a variety of forms of hydraulic analysis on water distribution networks from conventional modeling to state estimation. The mathematical basis for the algorithm is explained in the context of five different techniques, conventional exactly-determined problems, unconventional exactly-determined problems, the Proportional Demand Method, the Target Demand Method and state estimation. A small example network is presented and each of the five techniques is demonstrated on the network.


The paper presents a single algorithm that can perform a variety of forms of hydraulic analysis on water distribution networks from conventional modeling to state estimation including network calibration.


Davidson, J. and Bouchart, F. (2004) A New Versatile Technique for Hydraulic Models of Water Distribution Networks. Critical Transitions in Water and Environmental Resources Management: pp. 1-10. doi: 10.1061/40737(2004)447

Page 2 of 2




Year Month Day

2004 May

Field No. 3 Author


Primary Maslia M.L

Secondary Sautner J.B.

Tertiary Valenzuela C.

Additional Aral Bove

M.M. F.J.


Field Data Collection Activities for Water Distribution Systems serving Marine Corps Base, Camp Lujeune, North Carolina


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name CCWI Proceedings, Taylor and Francis

Location London UK



Page 1 of 2


Pressure Logger Pressure Measurement Verification Uncertainty Hazen-Williams

C-Factor Roughness Field Investigation Simulation Dynamic


An epidemiologic study is being conducted to determine if there is an association between exposure to contaminated drinking water and birth defects among children of women who lived at U.S. Marine Corps Base, Camp Lejeune, North Carolina while they were pregnant during 1968–1985. More than 12,000 pregnant women may have been exposed to well water contaminated with volatile organic compounds that was used for the potable water source and distributed through water-distribution systems at Camp Lejeune. Because of the paucity of historical water-distribution system operational data, information based on the operation of present-day water-distribution systems will be used for historical reconstruction. Present-day system operations will be modeled using water-distribution system models. To calibrate the models against hydraulic and water-quality parameters, field testing is being used to gather data and information on hydraulic, fate and transport, and operational characteristics of the water-distribution systems. Field activities include: (a) recording system pressures and storage tank water levels, and (b) conducting C-factor, fireflow, tracer, and travel time tests. Because this is an ongoing and active investigation, the authors present an overview and summary of activities to date and some initial results from field-testing activities.


Discussion of field testing activities, with some newer technologies. Included some lessons learned and pros/cons for different pressure equipment, tracer studies, etc.


Page 2 of 2




Year Month Day

2005

Field No. 3 Author


Primary Panguluri Srinivas



Additional


Water Distribution System Analysis: Field Studies, Modeling and Management. A Reference Guide for Utilities


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name USEPA




Page 1 of 2


Validation Tracer test


None published


This reference guide for water utilities provides detailed information and case studies on water distribution system modeling. Procedures for carrying out tracer studies are provided in great detail. A section on model calibration covers the following topics: hydraulic and water quality calibration; c-factor, fireflow and chlorine decay testing for calibration; a detailed case studies of calibration for a small suburban system and a large suburban pressure zone. The manual can be downloaded for free from USEPA.


Panguluri, S., Grayman, W.M, Clark, R.M.. (2005). Water Distribution System Analysis: Field Studies, Modeling and Management. A Reference Guide for Utilities. USEPA. Cincinnati, OH.

Page 2 of 2




Year Month Day

2005 June

Field No. 3 Author


Primary Augustinraj Rajah

Secondary Willnow Lindle D.

Tertiary Banciulescu Constantin

Additional


Managing Variations in Demand Patterns in a Large Distribution System Model


Book Reference

Conference Paper

Journal Paper

Technical Report



X






Page 1 of 2


Model Parameters Extended Period Demand adjustment


Water distribution systems serving larger metropolitan areas are characterized by multiple demographic regions with widely varying usage patterns. Accurately modeling such significantly different demands requires first that the allocation of customers’ demands be conducted accurately. However, these demands are based on monthly, quarterly or even yearly meter readings. Hourly or daily usage information is generally not available for individual customers so hourly patterns derived from large scale production records must be used. In addition, usage in different demographic areas changes seasonally to different degrees relative to average demands. Most modeling software packages can handle multiple demand patterns but usually rely on a single demand multiplier to reflect seasonal variations.

Metcalf & Eddy recently developed a computerized distribution system model for the Metropolitan District Commission (MDC) in Hartford, Connecticut. In order to account for the demand variations, the system was hence divided into twelve demand zones roughly corresponding to the pressure zones with larger zones subdivided based on additional geographical factors. Large users and un-metered usage were considered separately. Each demand zone was characterized by a unique demand pattern and seasonal multiplier. A system-wide water budget was utilized to aid calibration and track fractional demands of each demand zone while maintaining the overall system demand. Utilizing this model, M&E conducted a thorough analysis of the MDC s system and developed a program of improvements to address system deficiencies. In addition, the MDC now has a powerful tool to evaluate future changes within their system.


This was a poster presentation that discussed the impact of how different diurnal demand patterns had to be factored into the calibration of a larger model. A mass balance approach was needed since not all patterns had an average demand factor of one. Thus, a change in one pattern’s average demand factor required that one or more others had to be adjusted as well to maintain the overall demand.


Augustinraj, R., L. Willnow and C. Banciulescu, Managing Variations in Demand Patterns in a Large Distribution System Model, Proceedings - American Water Works Association Annual Conference and Exposition, June 2005, Poster 4.

Page 2 of 2




Year Month Day

2005

Field No. 3 Author


Primary Bocelli D.L.

Secondary Uber J.G.

Tertiary

Additional


Incorporating Spatial Correlation in a Markov Chain Monte Carlo Approach for Network Model Calibration


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name ASCE, EWRI 2005

Location



Page 1 of 2


Markov chain Monte Carlo statistical method Bayesian


To utilize a drinking water distribution system network model in any decision making process requires a calibrated network model. Typical calibration methods assume known consumer demands and adjust pipe roughness coefficients to fit pressure measurements and storage levels. However, these data contain little explicit information related to hydraulic residence time and travel path, which are necessary to improve water quality representations. Recent field-scale tracer tests have been shown capable of collecting data related to hydraulic residence time and flow path that can be used to adjust demand pattern multipliers to fit the observed tracer data. Both problem types (estimating pipe roughness coefficients or demand pattern multipliers) can have a spatially distributed component. This research extends an existing Markov chain Monte Carlo calibration algorithm by incorporating spatial correlation into the parameter estimation framework. Results will be generated using synthetic test data to evaluate the ability of the calibration algorithm to regenerate the known roughness coefficients or demand pattern multipliers.


Highly theoretical and statistical article with very little discussion of application of the method to distribution systems.


Page 2 of 2




Year Month Day

2005 June 14

Field No. 3 Author


Primary Martin, PE Delbert G.

Secondary Chang, PE Jennifer

Tertiary Harr, PE Peter

Additional Henke, PE

Mikowski, PE Taylor

Jennifer Ted Brad


Two Oregon Cities Prepare for the Initial Distribution System Evaluation and Improvement Operations


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name AWWA




Page 1 of 2


EPS extended period steady state data collection D/DBP Rule

IDSE



This is a case study of two community’s moves from a steady-state modeling system to an EPS modeling system. It is a bit light on details but does provide a good overview of the hurdles that one might face with the prospect of moving to an EPS modeling system.


Page 2 of 2




Year Month Day

2005 May 15 - 19

Field No. 3 Author


Primary Maslia M.L.

Secondary Sautner J.B.


Additional Grayman

Aral Green, Jr.

W.M. M.M. J.W.


Use of Continuous Recording Water-Quality monitoring Equipment for Conducting Water-Distribution System Tracer Tests: The Good, the Bad, and the Ugly


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name ASCE / EWRI

Location Anchorage Alaska USA



Page 1 of 2


Continuous recording water quality monitoring equipment (CR-WQME)

Tracer test


An emerging and innovative technology that is a possible alternative to manual sampling is the use of continuous recording water-quality monitoring equipment (CR-WQME) for collecting multiple ion-specific tracer data

Advantages of using CR-WQME include the ability to record continuous water-quality events (including unplanned events) during a tracer test at small time intervals of 15 minutes or less. This recording provides real-time data when using hand-held logger equipment to query the CR-WQME at each sampling location. Also, the labor needed to conduct the test is reduced in comparison to manual sampling.

Disadvantages could include the cost of multiple ion-specific sensors and units for large or complex systems, the effort required to calibrate the equipment by setting up a test-site water-quality laboratory, and the reliability of the equipment for long-term monitoring events

In this paper the authors assess the use of CR-WQME in conducting a tracer test at a military installation in North Carolina. Using results obtained from the tracer test, the authors found that CR-WQME is an emerging and innovative technology that still requires refinement and the use of some grab samples to provide quality-assurance and quality-control procedures during the tracer test. However, CR-WQME is an excellent option when designing and conducting multiple parameter tracer tests for water-distribution system model calibration activities.



Page 2 of 2




Year Month Day

2005 May 15 - 19

Field No. 3 Author


Primary Sautner J.B.

Secondary Maslia M.L.


Additional Grayman

Aral Green, Jr.

W.M. M.M. J.W.


Field Testing of Water-Distribution Systems at U.S. Marine Corps Base, Camp Lejuene, North Carolina, in Support of an Epidemiologic Study


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name ACSE/EWRI

Location Anchorage Alaska USA



Page 1 of 2


Field test tracer C-factor testing Fire-flow testing Calibration


An epidemiologic study was conducted to determine if there is an association between exposure to contaminated drinking water and birth defects among children of women who lived at U.S. Marine Corps Base, Camp Lejeune, North Carolina while they were pregnant during 1968–1985. More than 12,000 pregnant women may have been exposed to well water contaminated with volatile organic compounds that was used for the potable water source and distributed through water-distribution systems at Camp Lejeune. Because of the paucity of historical water-distribution system operational data, information based on the operation of present-day water-distribution systems was used for historical reconstruction. Present-day system operations were modeled using water-distribution system models. To calibrate the models against hydraulic and water-quality parameters, field testing is was used to gather data and information on system hydraulics, fate and transport, and operational characteristics of the water-distribution systems. Field activities included: recording system pressures and storage tank water levels, and conducting C-factor, fire-flow, tracer, and travel time tests. At the time of the presentation this was an ongoing and active investigation, thus the authors presented an overview and summary of activities to date and some initial results from field-testing activities.



Page 2 of 2




Year Month Day

2005 July 15

Field No. 3 Author




Tertiary Wood Don

Additional


“Calibration of Hydraulic Network Models”


Book Reference

Conference Paper

Journal Paper

Technical Report



×


Name John Wiley & Sons, Inc.

Location Hoboken NJ 07030 USA



14 14.1 - 14.23

Page 1 of 2


Microcalibration Water Distribution System Macrocalibration Pipe Roughness Factors Genetic Algorithms

Optimization


The validity of a hydraulic network model of a water distribution system depends largely on the accuracy of input data and the assumptions made in developing the model. Although much of the data can be obtained with a high degree of certainty, certain parameters exist that are either not readily available or difficult to obtain. Such parameters typically include pipe roughness factors and nodal demands and their spatial and temporal distribution. As a result of the difficulty of obtaining economic and reliable measurements of both of these parameters, final model values are normally determined through the process of model calibration. Model calibration involves adjustment of these and other uncertain network model parameters until the model results closely approximate actual observed conditions as measured from field data. This article describes a seven-step procedure for optimal calibration of water distribution network models. Historically, one of the most difficult steps in the process has been the final adjustment of pipe roughness values and nodal demands through the process of microlevel calibration. With the advent of recent computer technology, it is now possible to achieve good model calibration with a reasonable level of success. As a result, little justification remains for failing to develop good calibrated network models before conducting network analysis.


General overview of the model calibration process. Similar content to the 1997 AWWA paper.


Lingireddy, S., and Ormsbee, L.E., Wood, D.J., (2005) “Calibration of Hydraulic Network Models,” Encyclopedia of Water, Ed. Jay Lehr, John Wiley & Sons, 2005.

Page 2 of 2




Year Month Day

2006 August 27

Field No. 3 Author


Primary Boccelli Dominic

Secondary Grayman Walter

Tertiary Maslia Morris

Additional


WDSA 2006 Workshop Notes: Distribution System Tracer Studies-Design, Implementation and Case Studies


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name University of Cincinnati. 2006 Water Distribution System Analysis Symposium




Page 1 of 2


Validation Tracer test Flow measurement


None published


Topics covered: Planning Procedures Tracer Selection/Injection Methods Measuring Tracer Concentrations Case Studies

• U.S. Marine Corps Base U.S. Marine Corps Base, Camp Lejeune, North Carolina Camp Lejeune, North Carolina

• Hillsborough County Water Department

• A Tale of Tracer Studies in 3 Cities (Sweetwater Authority, CA; Charleston, SC; Green River/Rock Springs, WY)


Boccelli, D., Grayman, W., Maslia, M. (2006). WDSA 2006 Workshop Notes: Distribution System Tracer Studies-Design, Implementation and Case Studies. Water Distribution System Analysis Symposium . University of Cincinnati. Cincinnati, OH.

Page 2 of 2




Year Month Day

2006 April

Field No. 3 Author



Secondary Maslia Morris l.

Tertiary Sautner Jason B.

Additional


Calibrating Distribution System Models with Fire-Flow Tests


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name AWWA Opflow




32 4 10 - 12

Page 1 of 2


Fire-flow tests


This article discusses an alternative approach for conducting a fire-flow test developed as part of an ongoing study at the U.S. Marine Corps Base Camp in Lejeune, North Carolina. The enhanced test procedure was developed to improve labor efficiency associated with conducting fire-flow tests and to collect additional data for calibration purposes. The article lists five different flow conditions that were studied during the test and discusses test results. It was determined that this procedure, when compared to normal protocols for conducting flow tests, can be accomplished by smaller crews and performed faster, resulting in more data that could be used for model calibration.



Grayman, Walter M., Maslia, Morris L., Sautner, Jason B., (2006). ” Calibrating Distribution System Models with Fire-Flow Tests”. Opflow AWWA 32(4): 10-12.

Page 2 of 2




Year Month Day

2006 August 27 - 30

Field No. 3 Author


Primary Edwards Jerry

Secondary Brandt Malcolm

Tertiary

Additional


Quantitative Results of EPS Model Calibrations with a Comparison to Industry Guidelines.


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Eighth Annual Water Distribution Systems Analysis Symposium (WDSA), ASCE

Location Cincinnati Ohio USA



1 - 17

Page 1 of 2


Calibration Extended period

simulation Modeling

Water distribution Networks

Water distribution Systems

Water Quality


The concept for this paper originated with the question of how to define acceptable calibration criteria for water distribution models. A 2001 report by the AWWA Engineering and Computer Applications Committee (ECAC) titled Hydraulic and Water Quality Modeling of Distribution Systems: What Are the Trends in the US and Canada reported that only 48% of the 174 survey respondents considered their hydraulic model to be calibrated. Respondents had various definitions of calibration, used various methods to achieve calibration, and accepted varying accuracies of calibration. The definition of calibration criteria will become increasingly important as a result of increasing regulatory focus on water quality in the distribution system. The recently promulgated Stage 2 Disinfection By-Products Rule (Stage 2 DBF Rule) is the first EPA regulation that specifically identifies computer modeling as a method for evaluating monitoring locations. It allows water age and source trace results from calibrated distribution system models to be used as an alternative to extensive field measurements in initial studies required by the rule. Prior to promulgation of the Stage 2 DBP Rule, a 1999 report by the ECAC titled Calibration Guidelines for Distribution System Modeling suggested that additional meaningful discussion is needed among the United States (US) modeling community regarding the need and validity of calibration standards. To further that effort, this paper presents extended period simulation (EPS) model calibration results for several medium and large utilities across the US. The results of the calibrations are evaluated relative to the guidelines in the ECAC report. In consideration of different practices and their impact on calibration accuracies, information on the development and calibration of a model in the United Kingdom (UK) is also presented.


The paper presents extended period simulation (EPS) model calibration results for several medium and large utilities across the US. The results of the calibrations are evaluated relative to the guidelines in the ECAC report. In consideration of different practices and their impact on calibration accuracies, information on the development and calibration of a model in the United Kingdom (UK) is also presented.


Edwards, J. and Brandt, M. (2008) Quantitative Results of EPS Model Calibrations with a Comparison to Industry Guidelines. Eighth Water Distribution Systems Analysis Symposium 2006: pp. 1-17.

Page 2 of 2




Year Month Day

2006 June

Field No. 3 Author



Secondary Wu Zheng

Tertiary --- ---

Additional --- ---


How NOT to Use Optimization-based Model Calibration


Book Reference

Conference Paper

Journal Paper

Technical Report




Name AWWA – Annual Conference – 2006

Location San Antonio TX USA



Page 1 of 2


Optimization Pressure Measurement Field Testing


Optimized water distribution model calibration sounds easy. You construct your model, enter in some field data, hit GO and your model is ‘automatically’ calibrated by an optimization method. As with most things in life, however, nothing can be completely automated. “The devil is in the details”, and without some considerable care in setting up model calibration, the results can be not only inaccurate but misleading.

Most of the problems with optimized calibration go back to the quality of the data – garbage in, garbage out. Field data used in model calibration needs to be divided into two categories: target data that are used to drive the calibration and comparison data which, while not of good enough quality to drive the calibration, can be used to verify that the model is not wrong. Comparison data can’t be used to make adjustments.

In making adjustments to pipe roughness or demands, it is important to only use head data which has head loss significantly greater than the error in measuring such data. It is also essential to know the boundary conditions (tank levels, pump operation, PRV settings) when the data were collected.


A common pitfall in data used for optimized and/or manual calibration is assuming that the elevation of a node is the same as the elevation of the pressure gage used to provide calibration data. The elevation of the hydrant outlet or SCADA sensor used to measure pressure can be several feet different from the node elevation. This can lead to misleading results in some cases, especially using static flow data.

Finally, the model user has a great deal of control in setting ranges on calibration parameters and grouping of elements. Elements need to be grouped so that the elements whose attributes are being adjusted are sensitive to the field measurements or have properties in common with elements that are sensitive. The paper features practical tips and lessons learned for using an optimization-based calibration technique.


Page 2 of 2




Year Month Day

2006 August

Field No. 3 Author



Secondary DeFrank Nicholas

Tertiary Voglino Thomas

Additional Wood

Whitman Rick

Brian


Determining the Accuracy of Automated Calibration of Pipe Network Models


Book Reference

Conference Paper

Journal Paper

Technical Report



X X


Name WDSA Conference




Page 1 of 2


Pressure Measurement Roughness Flow Measurement


Methods to automatically calibrate water distribution system models have been available for some time but it is very difficult to prove that any method is correct because it is impossible to collect all of the data needed to verify calibration in a real water distribution system. For instance it is not possible to know the water usage in each household at all times or to look inside of every pipe. To obtain an accurate and complete data set for model calibration, a laboratory scale physical model of a water distribution system was constructed and an automated water distribution model calibration program, employing genetic algorithms, was used to calibrate the model of that system.


The results indicated that the automated calibration methods worked well in estimating pipe roughness, demands and locating closed valves. More specifically, the automated calibration model matched the measured flows and pressures in the system. It was able to identify if a valve was closed and where the demands were located. If given sufficient data, it was able to identify pipe roughness. The only problems occurred when the number of unknowns greatly exceeded the number of measurements. The model worked equally well regardless of whether the head loss equation used was the Hazen-Williams, Darcy-Weisbach or Manning equation.


Page 2 of 2




Year Month Day

2006 June

Field No. 3 Author



Secondary

Tertiary

Additional


Today’s Models: Bigger Isn’t Better without Calibration


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name AWWA – ACE 2006

Location San Antonio TX USA



Page 1 of 2


Calibration Distribution Systems Field measurements Initial Distribution System

Evaluation (IDSE) Water quality


Even bad models can look good when they’re dressed up with 3D graphics, animation and other advanced features of today’s powerful software. The trend toward bigger, more detailed hydraulic models makes it harder – not easier – to spot errors and focus on the big picture. That’s why calibration is probably more important than ever before. A model is only as accurate as its input data. Even the most advanced water quality modeling is meaningless if it is based on erroneous hydraulic results that do not reflect how the real system operates. Calibrating models establishes confidence in their predictions.

This paper presents three calibration case studies to demonstrate how field measurements resolved discrepancies between model predictions and real operating records. The first case study describes a model that did not agree with SCADA flow records at a pump station. Initially, the engineer adjusted the model’s pump curves to force agreement with recorded flows. However, subsequent tests showed the pumps were operating on the manufacturers’ curves. In the end, an unexpected source of error explained the discrepancy between the model and the SCADA records. The second case involves a booster station that pumped significantly lower flow in the model than in the real world. Inaccurate pump curves were not the cause because the curves in the model were based on field tests. Other field measurements showed a more surprising explanation for the discrepancy. The third case investigates why SCADA records of tank water levels did not match a model’s predictions. The model showed that a tank closer to a water plant floated a few feet higher than a more distant tank. However, SCADA records showed the opposite, an imbalance that concerned the operators. Field investigations tracked down the cause of this problem.



Page 2 of 2




Year Month Day

2006 August

Field No. 3 Author


Primary Lowry Steven G.

Secondary

Tertiary

Additional


Calibration Procedures for Extended Period Simulation Models


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name ASCE – Water Distribution Systems Analysis Symposium




Page 1 of 2


Steady-state Extended period

simulation Calibration SCADA System operations


Extended Period Simulation (EPS) hydraulic modeling is becoming increasingly popular for distribution system analyses, design applications, and water quality investigations. EPS models are useful because they can provide system performance information that may not be detectable with a steady-state model. Time variable system data, such as collected in a Supervisory Control and Data Acquisition (SCADA) network or registered on paper chart recorders, are used to configure and verify EPS models. Calibration is necessary to assure accurate EPS model results, and calibration procedures beyond those used for steady-state models need to be applied. It is important to develop accurate customer water usage profiles and employ appropriate model adjustment techniques to produce EPS simulated output that agrees with field measured system pressures, tank water levels, and metered flows.



Page 2 of 2




Year Month Day

2006

Field No. 3 Author


Primary Behzadian Kourosh

Secondary Jalilsani Fatemeh

Tertiary Ardeshir Abdollah

Additional Sabour Farhad


Verification of Sampling Design for Water Distribution Networks Calibration


Book Reference

Conference Paper

Journal Paper

Technical Report



X






NA NA 1 - 13

Page 1 of 2


Calibration Verification Genetic algorithm Sampling Water distribution


This paper presents the verification of sampling design problem for collecting data from a water distribution network. The aim is to compare the theory verification of model with the real one through developing a calibration procedure based on an optimization algorithm. At first, the multi-objective optimization model is assumed to be solved and the locations of measurement points are determined with different level of accuracy. Three approaches are considered for parameter uncertainty estimation in sampling design. With assuming the measurement points (i.e. the pressure heads) at each node, calibration procedure is made in order to adjust the best parameter (i.e. the pipe friction coefficients). Calibration is performed based on Genetic algorithm (GA) optimization approach. Determined Locations in the solutions of each scenario of sampling design are assumed to be the measurement points in each calibration procedure. Thus, the calibration results are compared in three scenarios with the same number of measurement. Comparison of the results is carried out based on the sum of squared deviations between all pressures calculated from the calibrated model and actual pressures with the real parameter. For the sets of the same measurement numbers, the best fitness solutions are selected based on the sum of squared error (SSE) criteria. The consistency of results for every specific number of measurements shows the robustness of methodology and its safe application to different cases.


A multi-objective genetic algorithm sampling approach for water distribution systems calibration.


Behzadian, K., Jalilsani, F., Ardeshir, A., and Sabour, F. (2006) Verification of Sampling Design for Water Distribution Networks Calibration. Water Distribution Systems Analysis Symposium 2006: pp. 1-13. doi: 10.1061/40941(247)65

Page 2 of 2




Year Month Day

2006

Field No. 3 Author



Secondary Brandt Malcolm

Tertiary

Additional


Quantitative Results of EPS Model Calibrations with a Comparison to Industry Guidelines


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name WDSA

Location



Page 1 of 2


Water distribution model calibration guidelines Extended period

simulation


The concept for this paper originated with the question of how to define acceptable calibration criteria for water distribution models. A 2001 report by the AWWA Engineering and Computer Applications Committee (ECAC) titled Hydraulic and Water Quality Modeling of Distribution Systems: What Are the Trends in the US and Canada reported that only 48% of the 174 survey respondents considered their hydraulic model to be calibrated. Respondents had various definitions of calibration, used various methods to achieve calibration, and accepted varying accuracies of calibration.

The definition of calibration criteria will become increasingly important as a result of increasing regulatory focus on water quality in the distribution system. The Stage 2 Disinfection By-Products Rule (Stage 2 DBP Rule) was the first EPA regulation that specifically identified computer modeling as a method for evaluating monitoring locations. It allowed water age and source trace results from calibrated distribution system models to be used as an alternative to extensive field measurements in initial studies required by the rule.

Prior to promulgation of the Stage 2 DBP Rule, a 1999 report by the ECAC titled Calibration Guidelines for Distribution System Modeling suggested that additional meaningful discussion is needed among the United States (US) modeling community regarding the need and validity of calibration standards. To further that effort, this paper presents extended period simulation (EPS) model calibration results for several medium and large utilities across the US. The results of the calibrations were evaluated relative to the guidelines in the ECAC report.

In consideration of different practices and their impact on calibration accuracies, information on the development and calibration of a model in the United Kingdom (UK) was also presented.

The takeaway message was that calibration criteria should not be prescriptive. It is important that modeling engineers and utilities recognize the limitations of available data. The costs for obtaining additional and more precise field data, and the costs for additional efforts to improve model calibration accuracies must be considered and weighed against the benefit of improved calibration accuracies.



Page 2 of 2




Year Month Day

2006 August 2 - 7

Field No. 3 Author



Secondary

Tertiary

Additional


“The History of Water Distribution Modeling”


Book Reference

Conference Paper

Journal Paper

Technical Report



×


Name ASCE




Page 1 of 2



Computers History


Computation of flows and pressures in networks of pipes has been of great value and interest for those involved with the design, construction and maintenance of public water distribution systems. Many methods have been used in the past to compute flows in networks of pipes. Such methods range from graphical methods to the use of physical analogies and finally to the use of mathematical models. This paper will attempt to catalog and review those methods that have been developed and applied since the dawn of the "computer age" in 1957 when the original Hardy Cross method was first adapted for solution using a computer in analyzing the water distribution system of the city of Polo Alto, California. Subsequent methods have included the "simultaneous node: method, the "simultaneous loop" method, the "simultaneous pipe" method, and the "simultaneous network" method. A brief review of the theoretical framework of each method will be presented along with a critique of the relative advantages and/or limitations of each method. With the advent of computer models of water distributions systems, it has now become possible to analyze more complex network components (e.g. pumps, tanks, PRVs, etc) of the water distribution system as well as to investigate more complex issues associated with their design and operation. Such additional applications have included 1) extend period simulations, 2) transient analysis, 3) water quality analysis, 4) optimal model calibration and design, 5) optimal operations, 6) optimal sampling plans, etc. The utility and feasibility of these additional types of applications can be demonstrated to be largely dependent upon the underlying simulation methods that were first developed beginning in the early 1960s.



Ormsbee, L., “The History of Water Distribution Modeling,” ASCE Water Distribution Specialty Conference, Cincinnati, OH, August 2-7, 2006.

Page 2 of 2




Year Month Day

2007 May

Field No. 3 Author


Primary Ray Rajan

Secondary Gangemi Tony

Tertiary Gennone Mike

Additional Juergens

Walski Bruce

Thomas


Lessons Learned in Calibrating an IDSE Model


Book Reference

Conference Paper

Journal Paper

Technical Report



X X


Name ASCE-EWRI Conference

Location Tampa FL USA



Page 1 of 2


Water Quality Field Testing


The Stage 2 Disinfectant By-Product Rule Initial Distribution System Evaluations (IDSE) requirements have lead utilities to redo their water distribution system models to conform to different standards than prior models which were created for master planning studies.

This paper describes the hurdles faced in converting an older water distribution model for Scranton, Pa. into a model that could be used for IDSE studies. Some of the issues included:

Need to fill in the distribution grid Need to better assign water use records to nodes Problems with data sources being in different (and nonstandard) coordinate systems Issues with boundaries between pressure zones Discontinuities in underlying CAD map Questionable or missing SCADA data Complexity of the Scranton system (e.g. 6 pipes in 3 pressure zones in the same street)


The problems encountered during the study and their solutions, which involved a mix of advanced data processing tricks to plain-old hard work, are described in this presentation.


Page 2 of 2




Year Month Day

2007 May

Field No. 3 Author


Primary Johnson Joel

Secondary Allen Roderick

Tertiary Green Antony

Additional Molla Saiful


Using Sensitivity Analysis and SCADA/Model Comparisons to Diagnose Model and System Issues


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name World Environmental and Water Resources Congress, ASCE

Location Tampa FL USA



1 - 10

Page 1 of 2


Calibration Modeling SCADA Sensitivity Analysis Water Distribution

Systems


Water distribution system computer modeling has long been a vital tool for system operations, capital planning and engineering design. Water distribution models typically rely on data collection from SCADA systems to provide reference data for model calibration. However, by loading snapshots of SCADA system data directly to the hydraulic model, both operational and model calibration issues can be diagnosed. A comparison of model predictions based on real-time operating conditions and SCADA flows and pressures allows utility personnel to immediately identify situations where the model and SCADA data diverge. Where the SCADA data and model prediction diverge, the problem may be related to an unknown operational condition or change, a dysfunctional SCADA device or inappropriate model parameters. These situations can be quickly diagnosed by observing the historical to present trends in the data and performing model sensitivity analysis to determine the relative impact of changing various model parameters, including operational constraints. The resulting diagnoses may improve the distribution system model, guide SCADA equipment repair or calibration work orders or suggest potential changes for more effective distribution system facility operation. This paper investigates case studies where x


SCADA snapshots were uploaded to the hydraulic model to set the boundary conditions for operating parameters, such as valve positions, tank levels and pump operational statuses. Both SCADA and model historical values were archived for system points where pressures and flows are recorded in the SCADA system, making the data trend for each viewable within the application. These trends were utilized to evaluate the model predictions versus SCADA records. Cases are presented where these trends diverge along with appropriate conclusions regarding system operation, the current state of the SCADA device and/or the hydraulic parameters of the model.


Johnson, J., Allen, R., Green, A., and Molla, S. (2007) Using Sensitivity Analysis and SCADA/Model Comparisons to Diagnose Model and System Issues. World Environmental and Water Resources Congress 2007: pp. 1-10. doi: 10.1061/40927(243)492

Page 2 of 2




Year Month Day

2007 August

Field No. 3 Author




Tertiary Walters Godfrey

Additional


Calibration of Water Distribution Hydraulic Models Using a Bayesian-Type Procedure


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name ASCE - Journal of Hydraulic Engineering




133 8 927 - 936

Page 1 of 2


Bayesian Analysis Calibration Markov Chains Optimization Pipe Networks

Water Dist Systems Network Analysis Measurement Data Pipe Roughness Correlation Factors


Estimating model parameters is a difficult, yet critical step in the use of water distribution system models. Most of the optimization-based approaches developed so far concentrate primarily on efficient and effective ways of obtaining optimal calibration parameter values. At the same time, very little effort has been made to determine the uncertainties , i.e., errors associated with those values and related model predictions. So far, this has typically been done using the first-order second moment (FOSM) method. Even though reasonably computationally efficient, the FOSM approach relies on several restrictive assumptions and requires computationally demanding calculation of derivatives. To overcome these limitations, the recently developed shuffled complex evolution metropolis (SCEM-UA) global optimization algorithm is linked to the Epanet2 hydraulic model and used to solve a least-squares-type calibration problem. The methodology is tested and verified on the Anytown literature case study. The main advantage of the SCEM-UA algorithm over existing approaches is that both calibration parameter values and associated uncertainties can be determined in a single optimization model run. In addition, no model linearity or parameter normality assumptions have to be made nor any derivatives calculated. The main drawback of the SCEM-UA methodology is that it could, potentially, be computationally demanding, although this is not envisaged as a major problem with current computers.


This citation offers a unique insight into the role of uncertainty as it plays-out in the model calibration process. It focuses on the use of a Bayesian recursive algorithm that (eventually) achieves stable/stationary parameter probability distribution functions (PDFs) for key model parameters. This process ultimately produces true calibration parameters at the conclusion of the algorithm deployment.


Page 2 of 2




Year Month Day

2007 September

Field No. 3 Author


Primary Colombo A.F.

Secondary Giustolisi O.

Tertiary

Additional


A metamodelling approach for water distribution system calibration


Book Reference

Conference Paper

Journal Paper

Technical Report



X



Location London UK



Page 1 of 2


Genetic Algorithms Parameter Estimation Roughness Pressure Measurements Objective Function

Optimization Gradient Method Flow Measurement Validation Correlation

Darcy-Weisbach


A data-driven strategy for conducting water distribution network pipe roughness calibration is introduced and explained. The approach is based on solving the inverse calibration problem by using measured head data from only selected locations in a network and then applying an evolutionary search strategy known as Evolutionary Polynomial Regression (EPR) in order to encapsulate network behaviour. EPR combines genetic programming, for symbolic regression, with genetic algorithms, for parameter estimation, in order to return straightforward polynomial formulas, in this case relating hydraulic conductivity with nodal head. The intention is that these equations could serve as either roughness approximations for some network pipes or help to identify which pipes and nodes may be of interest for closer examination in conventional calibration field tests, while also remaining easily comprehensible for system operators. The concept is illustrated with a case study basedon a proposed design for a real system in Puglia, Italy.



Page 2 of 2




Year Month Day

2007 September

Field No. 3 Author


Primary Vassiljev A.

Secondary Font L. Minguell

Tertiary Puust R.

Additional


Use of Pressure Differentials for Calibration of the Operational Water Distribution System


Book Reference

Conference Paper

Journal Paper

Technical Report



X



Location London UK



Page 1 of 2


Pressure Measurement Roughness EPANET Optimization


The accuracy of a Water Distribution System (WDS) model depends on how well it has been calibrated. Analysis of measurements showed that measured pressures often contain systematic errors. Another type of errors is inaccurate estimation of the elevations of junctions, which will lead to differences between measured and modeled pressures. In this paper we propose to use pressure differentials for the calibration of operational water distribution system containing thousands of pipes with different age. The pump speed is regulated in a way that pressure in the junction next to pump, is constant Pressures in other junctions depend on junction elevation and head loss in pipes. Head loss, in turn, depends on water consumption and roughness of pipe. Pressure differentials in a junction at times with high and low consumption do not contain systematic errors of loggers and errors due to inaccurate elevation of junction. It is shown also that this approach eliminates significantly the influence of leakages as well.



Page 2 of 2




Year Month Day

2008

Field No. 3 Author


Primary Southern Tucker


Tertiary Kjellgren Leon

Additional Seppie Bryan


Use of Fireflow Tests in the Calibration of a Water Distribution System Model


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name ASCE-EWRI World Environmental and Water Resources Congress




Page 1 of 2


Fire-flow tests


Fireflow (or hydrant flow) tests are frequently used in the calibration process for water distribution system hydraulic models. In such a test, hydrants are opened and flowed at a high flow rate in order to cause high flows and large head losses in the pipes leading to the hydrant. When a system is stressed in this manner, the behavior of the distribution system is more sensitive to factors such as pipe roughness, closed valves, demands, and PRV settings. By comparing field measurements of flow and pressure to model results for the same situation, model parameters can be adjusted (calibrated) to better represent the system behavior. As part of a master plan and hydraulic model development for The Joint Powers Water Board (JPWB) covering the Green River/Rock Springs/Sweetwater County area in southwestern Wyoming, fireflow tests and other field techniques were used to calibrate the detailed model. Approximately 30 fireflow tests were conducted as part of the calibration process. Additional operational information on the water system (water usage, tank levels, pump operation) was collected from the SCADA system. Subsequently, the hydraulic model was applied under the test conditions and parameter adjustments made to bring the model into better agreement with the field results. The method was found to be most effective in identifying unexpected closed valves, adjusting PRV settings and behavior, and to a lesser degree in adjusting roughness coefficients. The logistics, costs, practical experience and the calibration results are discussed herein.



Southern, T., Grayman, W., Kjellgren, L., and Seppie, B. (2008) Use of Fireflow Tests in the Calibration of a Water Distribution System Model. ASCE-EWRI World Environmental and Water Resources Congress.

Page 2 of 2




Year Month Day

2008 September 23

Field No. 3 Author


Primary West Paul

Secondary

Tertiary

Additional


A Better Way to Calibrate Grid Mains in Water Distribution Models: How Many Closed Valves Do You Want to Find


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name AWWA 2008 Distribution Systems Symposium and Exposition




Page 1 of 2


Hydraulic model Calibration Field Testing Closed Valves Cost

Hydraulic grade C-factor Roughness Pressure Gauge


This Power Point presentation begins by listing five main discussion points. Closed valves in water distribution systems is the first, along with causes of closed valves, and closed valve implications. Field testing and model calibration is the second topic and includes hydraulic grade line test, traditional system wide test, and typically conducted trunk mains (e12 inch). A case study of a suburban Washington, D.C. utility is summarized. Cost implications of newer test methods are presented, along with business process integration. Includes figures.


This presentation highlights the importance of model calibration to specifically find closed valves. The impact of closed valves is reduced available fire flow, stagnant water, and increased operational and engineering costs. The main case study reported that it was hard to determine closed valves during calibration if the roughness values are low (ie a significant cleaning and lining program was required).


Page 2 of 2




Year Month Day

2008 September 23

Field No. 3 Author


Primary Willnow Lindle

Secondary Sparks David

Tertiary Roseweir Alex

Additional


A Time-Saving Method for Getting More Data Out of your Tracer Studies


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name AWWA 2008 Distribution Systems Symposium and Exposition




Page 1 of 2


Dose Tracer Water Quality Fluoride Disinfection


The City of Northampton, Massachusetts began operations of their 6.5 mgd water treatment plant in January, 2008. Prior to delivering water to its customers, the Massachusetts Department of Environmental Protection (DEP) required that the disinfection contact time of the plant's clearwell be determined with a tracer study. The tracer study was conducted by Metcalf & Eddy in accordance with the guidelines set forth in the U.S. Environmental Protection Agency's Guidance Manual on Determining Disinfection Contact Time. Because the plant was not on-line at the time of the tracer study, several constraints were in place that limited the amount of time and the flow rate at which the study could be conducted. This paper presents details on an efficient approach that M&E used and demonstrates how T10/T was calculated for both the increasing and receding dose tests without achieving a steady fluoride level between tests.


No mention of calibration or use of hydraulic models in this paper.


Page 2 of 2




1 Month Day

2008

Field No. 3 Author


Primary Bean Thomas K.

Secondary McKenzie James W.

Tertiary

Additional


Field Data for the Calibration of a Hydraulic Model


Book Reference

Conference Paper

Journal Paper

Technical Report



X



Location Reston VA 20191 – 4400 USA



Pipelines 2008 1 - 12

Page 1 of 2


Data Collection Field Study Field Instruments Pressure Measurement Flow Measurement

Pump Test Hydrant Test C-Value Test


The Ft. Polk Directorate of Public Works (DPW) has directed the Corps of Engineers, Ft. Worth District (COE) to analyze the existing water system infrastructure and determine its capacity to support existing and future use. In order to perform this analysis the Corps of Engineers created a hydraulic model of the Fort Polk water system. This paper describes the field work conducted to provide the data necessary to calibrate the hydraulic model.


Discussion of methods used to collect field data for calibrating a hydraulic model. Electronic data was collected for pressures and velocities. Paper illustrates how velocity data is used to create a velocity profile and Pump curve testing a data collection is discussed Roughness coefficient testing is detailed Good summary of the types of testing needed for calibration of hydraulic models


Thomas K. Bean and James W. McKenzie (2008) Field Data for the Calibration of a Hydraulic Model. Pipelines 2008: pp. 1-12. Product Number: doi: 10.1061/40994(321)73

Page 2 of 2




Year Month Day

2008 June 25

Field No. 3 Author


Primary Lind

Secondary Walski Tom

Tertiary Lund Tom

Additional


Water Transmission System Hydraulic Model Update and Calibration


Book Reference

Conference Paper

Journal Paper

Technical Report



X X


Name American Water Works Association | 2008 DSS Conference

Location Austin TX



Page 1 of 2


Case Study Data


This PPT slide show appears to be a case study. In particular, it appears to be the project wrap-up presentation. It does discuss data requirements for a successful hydraulic calibration. It also notes lessons learned with calibration challenges.



Page 2 of 2




Year Month Day

2008

Field No. 3 Author


Primary Cole Scott

Secondary

Tertiary

Additional


Calibrating a GIS-based All-pipes EPS Model: A City of Denton Case Study


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name American Water Works Association DSS




Page 1 of 2



This powerpoint presentation begins by providing a brief overview of the City of Denton's distribution system. Topics covered include: physical model; demand allocation; field testing; operational controls; and, EPS calibration. Lessons learned include: good communication with operations staff is essential; geographic information system (GIS) can be set up with modeling in mind; site visits are important; make sure you get a handle on VFDs; triple check elevation data; diurnal curves for small pressure zones can be difficult; and, don't get caught up in statistics.



Page 2 of 2




Year Month Day

2008

Field No. 3 Author


Primary Behzadian Kourosh

Secondary Ardeshir Abdollah

Tertiary Jalilsani Fatemeh

Additional Sabour Farhad


A Comparative Study of Stochastic and Deterministic Sampling Design for Model Calibration


Book Reference

Conference Paper

Journal Paper

Technical Report



X






NA NA 1 - 11

Page 1 of 2


Roughness Uncertainty EPANET Gradient Method Optimization

Calibration Sampling Deterministic Stochastic Water distribution


This paper presents and compares two approaches, stochastic and deterministic sampling design, for the purpose of calibrating water distribution system model. Both approaches use a multi-objective genetic algorithm known as NSGA-II to identify the whole Pareto-optimal front of optimal solutions. The relevant objective functions are to maximize the calibrated model accuracy and to minimize the number of sampling devices as a surrogate of sampling design cost. In the deterministic approach, optimal solutions are identified based on the assumed values for calibration parameters. However, the uncertainty of calibration parameters is taken into account in the stochastic approach with some pre-defined probability density functions. Two different stochastic approaches, including noisy fitness function and Monte Carlo simulation, are considered in this study. The efficacy of considering stochastic sampling design rather than deterministic one is assessed by evaluating their objective functions in the simulation of 10000 sampling design problems, each of which is constructed with randomly generated calibration parameters. The stochastic approach is first test on an artificial case study. Then it is applied to a real world water distribution system known as Mahalat model in the central part of Iran. The results of comparison show significant improvements in optimal solutions when using stochastic approaches of sampling design.


Multi-objective sampling approach using a genetic algorithm.


Behzadian, K., Ardeshir, A., Jalilsani, F., and Sabour, F. (2008) A Comparative Study of Stochastic and Deterministic Sampling Design for Model Calibration. World Environmental and Water Resources Congress 2008: pp. 1-11. doi: 10.1061/40976(316)482

Page 2 of 2




Year Month Day

2008 July / August

Field No. 3 Author


Primary Jonkergouw P. M.

Secondary Khu S. T.

Tertiary Kapelan Z. S.

Additional Savic D. A.


Water Quality Model Calibration Under Unknown Demands


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name ASCE – Journal of Water Resources Planning and Management




134 4 326 - 336

Page 1 of 2


Water Quality Calibration Water Dist Systems Hydraulic Models Chlorine

EPANET Optimization Gradient Method Stochastic methods Parameter Adjustment


It has often been cited that a water distribution system _WDS_ hydraulic model needs to be highly accurate before it may be used in combination with a water quality model (WQM) to simulate the dispersion and decay of a residual disinfectant. However, even a well-calibrated WDS hydraulic model may not have data relating to the specific water demands during a given period, which may impede WQM calibration. This study examines using residual disinfectant data to calibrate a WQM under unknown or uncertain demands by calibrating a residential demand multiplier pattern (DMP) in tandem with the WQM parameters. Two artificial scenarios and one real case study are investigated. The artificial scenarios are used to (1) verify the proposed methodology under ideal conditions and (2) validate the proposed methodology when the hydraulic model and calibration data contain realistic errors. The real case study uses residual chlorine data and a WDS model for which a hydraulic and WQM calibration had been performed previously. The estimated demands from the real case study are validated using tracer test data. Results from the artificial case studies may be summarized as follows: (1) the proposed methodology can estimate the demands and calibrate WQM parameters correctly, although increasing model and calibration data errors adversely affect calibration results; (2) the calibrated WDS models reproduce the true residual chlorine concentrations with very little error. Results from the real case study indicate that the original WQM calibration was performed using underestimated WDS demands. Tracer test data confirm that the calibrated DMP provides good hydraulic velocities. The calibrated WDS model from the real case study is in good agreement with measured residual chlorine concentrations. The mean absolute error between the simulated chlorine concentrations from the calibrated network model and the observed values is 0.059 mg/L.


This citation highlights several important aspects of water quality model calibration. It also reinforces the notion that adequate hydraulic or distribution model calibration may not necessarily yield adequate water quality model calibration. All key concepts are reinforced with one case study involving three separate scenarios.


Page 2 of 2




Year Month Day

2009 September

Field No. 3 Author



Secondary --- ---

Tertiary --- ---

Additional --- ---


Finding Closed Valves in Your Distribution System


Book Reference

Conference Paper

Journal Paper

Technical Report



X X


Name AWWA – DSS 2009

Location Reno NV USA



Page 1 of 2


Valves Pressure Measurement Hydrant Flow Test


With the exception of pressure zone boundaries, isolation valves (usually gate valves) are normally supposed to be fully open. Most are. However, in virtually any water system there are some valves that are supposed to be fully open but are closed or partly closed. Because of loops in water systems and the low velocities in most mains most of the time, the closed valves can go unnoticed until that pipe must carry a large flow such as during a fire or other emergency. Most water utilities have hydraulic computer models of their systems. Closed valves are often found as a by-product of calibration of these models. The model can’t be calibrated when the valves is open but by shutting one or more valves in the model, the model results match field results. This indicates that the valve is likely to be closed.

Because of low velocity in most water mains, there is not sufficient head loss to detect a closed valve. Instead, the velocity and head loss must be increased to create a situation where the pressure drop due to the closed valves is measurably greater that that if the valve were open. Usually this is accomplished by opening a fire hydrant to increase velocity. The larger the flow and the more pressure gages involved, the more likely it is that the closed valves can be located.


An example problem will be presented where the results of a fire hydrant flow test and a computer model were used to identify closed valves in a system. A suggested procedure will be presented and some tips will be given to increase the likelihood that this process will be successful.


Page 2 of 2




Year Month Day

2009 October

Field No. 3 Author


Primary Sumer Derya

Secondary Lansey Kevin

Tertiary

Additional


WDS Calibration and Assessment for Alternative Modeling Objectives


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Urban Water Journal – Taylor & Francis

Location UK



6 4 265 - 277

Page 1 of 2


Calibration Hydraulics Model Objectives Water Distribution Network Analysis

Uncertainty Parameter Estimation Parameter Adjustment Optimal Design Variance


A water distribution system model may be developed for different purposes, and the required prediction accuracy is not necessarily the same for each goal. As such, the number of data necessary to adequately calibrate a system for different purposes varies depending upon the intended use. To examine the impact of model purpose on the calibration process, a real system is modeled for two objectives: daily pump scheduling and system expansion design. Results indicate that an operational model can be calibrated with limited data since the sensitivity to decision is small. A system expansion model requires more data since the design demand condition causes critical low pressures and model pressure predictions are strongly influenced by calibrated parameters.


This citation offers a sound example of the range of calibration requirements and sensitivity outcomes that can arise in modeling for different end objectives. This key point is illustrated by a case example.


Page 2 of 2




Year Month Day

2009 September 1 – 3

Field No. 3 Author


Primary Boivin E.L.S

Secondary Mansoor M.A.M

Tertiary Hidderley J.

Additional Vairavamoorthy K.


Modeling and calibration of water distribution networks: A case study from the Wessex region


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name CRC Press, Taylor & Francis Group

Location London UK



159 – 165

Page 1 of 2


Water distribution system (WDS)

Wessex region Field test Pressure logger Model calibration

District metering area (DMA)

Consumption Demand Geographic information

system (GIS)


Water distribution systems (WDS) are an important lifeline infrastructure system. Understanding the hydraulic performance of these systems is essential to maintain a reliable and sustainable water supply to consumers. Hydraulically inefficient systems are both uneconomical and unsustainable. Hydraulic performance of WDS changes with time due to aging components, environmental factors, such as soil condition and water composition and increase m water demand.

WDS have kilometres of complex networks of buried pipes. Physically determining the conditions and the performance of those assets is massively expensive and impractical. However by computer modelling and calibrating the water network, the system performance and the condition of the WDS can be identified. The main objective of computer modelling and calibration of WDS is to simulate the existing conditions of the WDS, pipes, valves, pumps and reservoirs.

The first step in computer modelling of WDS will be model building, which is generally carried out using network analysis software wh1ch is based on a demand driven analysis method (where demands at the nodes are satisfied regardless of the system pressure) as opposed to the pressure dependent demand approach. Although demand driven approach docs not accurately predict the network conditions at low pressure situations, it has been accepted that this approach is capable of producing satisfactory results during normal operation of the network. Field tests follow the model build process and arc carried out to monitor the field conditions. Measurements .r,· taken on pressures, levels and flows at various locations of the network. Pressures and reservoir levels are measured using pressure loggers and level transducers whereas flows in the Wessex Water Network are obtained from telemetry data.

In this paper the methodology and techniques applied in the water industry to calibrate water distribution systems arc presented. In particular, the paper discusses the model building process, field test planning and data collection, demand analysis, leakage assignment, calibration and issues encountered during these processes. Furthermore the paper demonstrates how the anomalies in the WDS arc determined from the calibration results, especially undetected leakage or illegal connections, areas of high head loss due to deteriorated assets or unsuitable pipe diameters and control settings. The methodology is demonstrated using case study networks in the Wessex Water region.


This paper was presented at the tenth International Conference on Computing and Control, Sheffield, United Kingdom, September 1–3, 2009. The authors describe procedures for obtaining field data, building a model of the water distribution system, and calibrating the model. The methods described are applied to the Wessex region in the UK as a case study.


Boivin, E.L.S., Mansoor, M.A.M., Hidderley, J., and Vairavamoorthy, K., "Modeling and calibration of water distribution networks: A case study from the Wessex region,” In: Proceedings of the tenth international conference on computing and control for the water industry, CCWI 2009, September 1–3, 2009, Sheffield, UK, p. 159–195.

Page 2 of 2




Year Month Day

2009 March

Field No. 3 Author




Tertiary

Additional


Editorial


Book Reference

Conference Paper

Journal Paper

Technical Report



X



Location Mortimer Street London W1T 3JH UK



6 1 1 - 2

Page 1 of 2


Model Calibration


Hydraulic and water quality simulation models are widely used nowadays by planners, water utility personnel, consultants and many others involved in analysis, design, operation or maintenance of water distribution systems (WDS). As with all mathematical models, WDS models need to be calibrated before useful results may be obtained. This special issue contains a number of papers dealing with important topics related to WDS simulation model calibration.


This citation provides an overview and introduction to six (6) papers on model calibration that appeared in the March 2009 edition of the Urban Water Journal.


Zoran S. Kapelan & Dragan A. Savic (2009) Editorial, Urban Water Journal, 6:1, 1-2, DOI: 10.1080/15730620902797216

Page 2 of 2




Year Month Day

2009 March

Field No. 3 Author


Primary Savic Dragan

Secondary Kapelan Zoran

Tertiary Jonkergouw Philip

Additional


Quo Vadis Water Distribution Model Calibration?


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Conference Paper

Journal Paper

Technical Report



X






6 1 3 - 22

Page 1 of 2


Water Distribution Hydraulics Modeling Network Analysis Quality

Steady-State EPS Optimization Measurement Errors Sampling Design


Hydraulic water distribution system (WDS) simulation models are widely used by planners, water utility personnel, consultants and many others involved in analysis, design, operation or maintenance of water distribution systems. Similarly, water quality models that work in concert with hydraulic models are now commonly used to simulate the dispersion of and changes in water quality in a water distribution network. As with all mathematical models, WDS model parameters (hydraulic and water quality) require calibration before useful results may be obtained. Nowadays, automated calibration procedures are widely available for hydraulic models, but less so for water quality models. Even when they are available as commercial software, the use of these advanced calibration tools in engineering practice has been limited. This paper provides a review of model calibration approaches and considers future challenges and directions.


Solid discussion of model calibration history, approaches, methodology, data elements, and future considerations.


Dragan A. Savic , Zoran S. Kapelan & Philip M.R. Jonkergouw (2009) Quo vadis water distribution model calibration?, Urban Water Journal, 6:1, 3-22, DOI: 10.1080/15730620802613380

Page 2 of 2




Year Month Day

2009 March

Field No. 3 Author


Primary Speight Vanessa

Secondary Khanal Nabin

Tertiary

Additional


Model Calibration and Current Usage in Practice


Book Reference

Conference Paper

Journal Paper

Technical Report



X






6 1 23 - 28

Page 1 of 2


Water Dist Modeling Urban Water Systems Water Quality Data Collection Data Quality

GIS SCADA Field Testing Model Calibration Goodness of Fit


The theoretical standards for hydraulic model calibration have been examined in numerous studies. However, the reality of modelling for real distribution system operators is that an ideal calibration often cannot be achieved due to lack of resources, data scarcity and time constraints. This paper will discuss the typical model calibrations that are currently carried out in the USA, including the types of data that are most commonly used, the techniques for calibration and the ability to achieve a calibration of sufficient accuracy to address the modelling goals. The tradeoffs between level of model accuracy and real-world constraints will be presented for different categories of modelling ranging from transmission master planning to residual disinfectant predictions.


Solid coverage of model calibration benefits and challenges. Discussion of data life-cycle, including data collection, validation, and use. Discussion of calibration methodologies, including a focus on C-factor adjustments, fire flow tests, generalized flow and pressure testing/matching, tank level matching, and demand adjustments. Also an overview of participating water utilities and calibration criteria.


Vanessa Speight & Nabin Khanal (2009) Model calibration and current usage in practice, Urban Water Journal, 6:1, 23-28, DOI: 10.1080/15730620802566851

Page 2 of 2




Year Month Day

2009 March

Field No. 3 Author


Primary Jacobsen Laura

Secondary Kamojjala Sri

Tertiary

Additional


Tools and Processes for Calibrating Large All-Pipes Models


Book Reference

Conference Paper

Journal Paper

Technical Report



X






6 1 29 - 38

Page 1 of 2


Drinking Water IDSE Network Analysis Water Dist Modeling Model Calibration

SCADA Field Data Collection EWQMS Operational Goals Automated Tools


Historically, computing power and software limitations necessitated that only the most significant features of the distribution system are represented. In recent years, advances in hardware and software technologies have provided the ability to include all the pipes in the distribution system. An all-pipes hydraulic model with 157,000 pipes was developed at the Las Vegas Valley Water District (District) utilising a one-to-one relationship between model features and GIS features. Calibration of such large models poses challenges in terms of collecting and handling large amounts of data from various sources, including SCADA, GIS and an enterprise database. This paper presents data integration, processes and tools developed at the District for calibration of a large all-pipes model.


Solid discussion of model calibration processes and model use characteristics as they pertain to the all-pipes distribution model for Las Vegas Valley Water District.


Laura B. Jacobsen & Sri Kamojjala (2009) Tools and processes for calibrating large all-pipes models, Urban Water Journal, 6:1, 29-38, DOI: 10.1080/15730620802566869

Page 2 of 2




Year Month Day

2009 March

Field No. 3 Author


Primary Giustolisi O.

Secondary Todini E.

Tertiary

Additional


Pipe Hydraulic Resistance Correction in WDN Analysis


Book Reference

Conference Paper

Journal Paper

Technical Report



X






6 1 39 - 52

Page 1 of 2


Water Dist Modeling Network Analysis Hydraulics EPANET Head Loss

Demand Distribution Minimization Genetic Algorithm Hydraulic Resistance


The analysis of a looped water distribution network, operating under pressure and in steady flow conditions, can be accomplished once the topology of the network, the geometry of the pipes, the water demands at the nodes and the head value of at least one node are known. In a water distribution network (WDN), water demands are assigned to the nodes, although in reality they are distributed along the pipes converging at such nodes. This classic assumption represents the total demand along a pipe as two lumped withdrawals at its terminal nodes. This paper demonstrates that the above approximation is wrong because it generates head loss errors which may be significant when network analysis is performed for calibration, system design, real-time operations, rehabilitation strategies, optimal operation studies, reliability analyses, etc. Therefore, an extension of the global gradient algorithm (GGA) for network analysis is proposed which entails a modified GGA permitting the effective introduction of the lumped nodal demands, and without forfeiting a correct physical representation of head losses, by means of a pipe hydraulic resistance correction.


Discusses a demand and resistance adjustment methodology as applied along the length of a pipe segment.


O. Giustolisi & E. Todini (2009) Pipe hydraulic resistance correction in WDN analysis, Urban Water Journal, 6:1, 39-52, DOI: 10.1080/15730620802541623

Page 2 of 2




Year Month Day

2009 March

Field No. 3 Author


Primary Wu Zheng

Secondary

Tertiary

Additional


Unified Parameter Optimisation Approach for Leakage Detection and Extended-Period Simulation Model Calibration


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Technical Report



X






6 1 53 - 67

Page 1 of 2


Water Dist System Hydraulic Model Leakage Detection Water Loss Model Calibration

Genetic Algorithm Optimization Roughness EPS Peak Demand


Leakage detection is of great interest and significance for water utilities. There are different field testing apparatuses developed for leakage detection, but no systematic modelling approach was available for predicting the most likely leakage hotspots that might guide leakage detection crew to quickly locate exact leakage locations. In this paper, leakage is represented as pressure-dependent emitter flow at a node in a water distribution model. Leakage detection is formulated as a nonlinear parameter identification problem to search for the possible emitter node locations and the emitter coefficients while minimising the same objective function as model calibration, namely the distance between the field-observed and the model-simulated flows and hydraulic grades. Thus the leakage detection optimisation is developed as an integral component of the unified model parameter identification framework. The comprehensive methodology is applied to the water system of a district meter area (DMA) in the UK. It illustrates the effectiveness of the unified approach for both leakage hotspot detection and extended-period simulation model calibration using the real field data.


Solid discussion of calibration and leakage detection theory. Also discusses influence of leakage on model calibration results. Main concepts are reinforced with one case study.


Zheng Yi Wu (2009) Unified parameter optimisation approach for leakage detection and extended-period simulation model calibration, Urban Water Journal, 6:1, 53-67, DOI: 10.1080/15730620802541631

Page 2 of 2




Year Month Day

2009 March

Field No. 3 Author


Primary Branisavljevic Nemanja

Secondary Prodanovic Dusan

Tertiary Ivetic Marko

Additional


Uncertainty Reduction in Water Distribution Network Modeling Using System Inflow Data


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6 1 69 - 79

Page 1 of 2


Genetic Algorithm Fuzzy Sets Monte Carlo Nodal Demand Uncertainty Analysis

Sensitivity Analysis Constraints Flow Measurement EPANET MATLAB


In water distribution network (WDN) modelling, nodal demand is the sum of flows taken by users associated with a computational node. User demands are not fixed in time; rather they are stochastic. Hence, nodal demand is a model parameter with high uncertainty, which is propagated throughout the WDN model, thus also rendering the output values (node pressures and pipe discharges) uncertain. Total water inflow into the network can be accurately measured using flow meters. This paper investigates how knowledge of system inflow can be used as a constraint in WDN modelling, taking into consideration the uncertain nodal demands, and consequently reducing the uncertainty of the model output. Fuzzy sets were used to represent the uncertain demands and modified genetic algorithms were used to find the optimal solutions. As a test case, a set of data from a real WDN was used. The uncertainty of the WDN model output was computed for two cases: first, with the total network inflow taken into consideration; and second, with the inflow used as a constraint. Although the methodology that handles the constraints needs significantly greater computational effort, its results provide a more realistic insight into model uncertainty. The proposed methodology was verified using Monte Carlo simulation.


Solid discussion of the concept of uncertainty in model calibration, particularly as the concept applies to input parameters and variables.


Nemanja Branisavljevi , Duan Prodanovi & Marko Iveti (2009) Uncertainty reduction in water distribution network modelling using system inflow data, Urban Water Journal, 6:1, 69-79, DOI: 10.1080/15730620802600916

Page 2 of 2




Year Month Day

2009 February 20

Field No. 3 Author


Primary Koppel T.

Secondary Vassiljev A.

Tertiary

Additional


Advances in Engineering Software


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X


Name Elsevier

Location



40 659 - 664

Page 1 of 2


Water Distribution Calibration Roughness Levenberg-Marquardt Epanet


The aim of the paper is to demonstrate that the Levenberg–Marquardt algorithm can give successful results when operational water distribution systems are calibrated with the proper selection of parameter increment for the calculation of partial derivatives. The functional dependence of pipe roughness on age, which describes linear and nonlinear dependences, is proposed for the calibration of a model of a water distribution system containing pipes of different age. It is also shown that the visualization of response surface on a coarse grid is very useful for the analysis of the results.


This paper discusses a mathematical method by which roughness can be calculated by the age of the pipe. This exercise, while interesting, does not pose value to the average modeler, as the estimation techniques are extremely complicated. Most average modelers will not likely read beyond the portion of the paper that describes roughness as a linear function with respect to age. Comparing data from sparse flow studies will plug the age data into a spreadsheet and ‘calculate’ the roughness of the pipe. Please, do not misunderstand, this is an interesting topic, but its realistic value must be examined.


Page 2 of 2




Year Month Day

2009 September

Field No. 3 Author


Primary Carrico Nelson J.G.

Secondary Covas Didia I.C.

Tertiary Soares Alexandre K

Additional


Calibration methodology for hydraulic transient models incorporating unconventional dynamic effects


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X



Location Sheffield UK



Page 1 of 2


Transient Guidelines Steady-State Roughness Dynamic


The paper aims at the presentation of guidelines for the calibration of hydraulic transient models taking into account different dynamic effects (i.e., unsteady friction and pipe non-elastic behaviour) and applied to different types of pipe systems. A hydraulic transient simulator has been developed, which incorporates different numerical schemes for steady state friction, unsteady friction and the pipe wall rheological behaviour. A data collection programme has been carried out in an experimental facility at Instituto Superior Técnico, collecting pressure data during simulated transient events; the facility has a reservoir pipe-valve configuration; the pipe is made of high density polyethylene (HDPE), is 203 m long and has 50 mm inner diameter. Calibration guidelines that are divided in steady state calibration and transient state calibration, are presented. The developed simulator is calibrated and validated by following the proposed methodology and by using physical data collected in laboratory conditions. The main conclusions of the research work and suggestions for future studies are presented.



Page 2 of 2




Year Month Day

2009

Field No. 3 Author


Primary Govondan Sharavan

Secondary Walski Tom

Tertiary Cook Jack

Additional


Hydraulic Models – Helping You Make Better Decisions


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Journal Paper

Technical Report



X


Name National Rural Water Association

Location Duncan OK 73533 USA



30 1 First Quarter 2009 34 - 40

Page 1 of 2


Hydraulic Model Decision Making Infrastructure Planning Asset Management Problem Solving

Model Creation Pipe Sizing Pump Selection Model Uses Model Overview


The abstract for this article was not available. The following is a brief synopsis of the article contents:

This article is intended to help Utility Managers, Engineers, and Operators understand how a hydraulic model can be useful to them. It includes a discussion of common uses of a hydraulic model for infrastructure planning and how it is prohibitively expensive to install system elements as part of a “what-if analysis”. Hydraulic models are ideal tools to help utilities examine common issues that arise in infrastructure planning. It includes a basic discussion of what a hydraulic model is and how it uses mass continuity and the energy equation to solve hundreds or thousands of equations simultaneously. The authors also further describe the basics of steady state and extended period simulations and the various other types of model runs such as water quality simulations, criticality, fire flow analysis, energy analyses, and maintenance flushing plans. The article also gives a brief description of the type of data needed to create a hydraulic model to assist the reader in a basic understanding what is needed for model creation. The article concludes by describing the four primary areas of problem solving that the model is used for 1) Pipe Sizing, 2) Pump Selection, 3) Emergency Planning, and 4) Pressure Zone Layout.


The article is written with an audience of utility managers, engineers, and operators to introduce them to what a hydraulic model can do. It has essentially no discussion of model calibration which limits its usefulness for this project.

This article is very effective for its intended audience in order to understand how a model could be useful for solving common problems that utilities face when completing infrastructure planning. It gives a basic overview of what a model is and how a model is created as well as the major uses that a model is used for.


Sharavan, G., Walski, T., & Cook, J., “Hydraulic Models – Helping You Make Better Decisions”, Rural Water, First Quarter 2009, Vol 30, Number 1, pp 34-40

Page 2 of 2




Year Month Day

2010

Field No. 3 Author


Primary Nyende-Byakika S.

Secondary Katashaya Ngirane

Tertiary Ndambuki J.M.

Additional


Behavior of Stretched Water Supply Networks


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X


Name Nile Basin Water Science & Engineering Journal

Location



3 1 51 - 60

Page 1 of 2


Water supply network Hydraulic impact simulation pressure velocity

Flows Service levels


A growing demand for massive water supply systems has put stress on the existing water supply networks, as a result of increasing urban populations, industrialization, and rising water consuming lifestyles. When the systems inevitably expand, other problems set in, such as the likelihood of development of transient flow conditions that range from excessive and deficient pressures, fluctuating pressures, open-channel flow conditions, and decreasing flows culminating into very low pressures with very low flow or sometimes no flow at all. Such problems would be best solved through infrastructural upgrades; however this is an expensive option not easily affordable in many developing countries that are often faced with this problem, a case of Kampala Water Supply. Many pressurized water supply systems thus exhibit open channel flow behavior due to excessive low transient pressure conditions; while some sections operate as gravity flow systems under low reservoir conditions and pressurize under high reservoir level conditions as force mains with low pressures. This type of situation is difficult to analyze using conventional approaches and may require special treatment different from that of fully pressurized systems, with more sophisticated/complex algorithms and robust scenario management to model. A further complicating factor is that most water supply modeling softwares assume a demand-driven analysis, which is not always the case since in several real cases, water supply to consumers is less than the consumer asks for. There is therefore a need to analyze the situation of unstable flows and pressures in order to give very useful insight into the system state and condition. To this end, numerical simulation has been identified as a modern tool in the management of piped water supply as it would identify situations of low-pressure-open-channel flow conditions even when in a pressurized network.

The authors assessed the Kampala Water Supply area under 3 conditions: (1) Assessment of water supply before 2 major extensions were made (2) Assessment after 2 major extensions were made (3) Assessment after more extensions were made

The research enabled improved understanding and quantification of the exact impact that water supply expansions have on network hydraulics.



Page 2 of 2




Year Month Day

2010 September 21

Field No. 3 Author



Secondary

Tertiary

Additional


The Value of Hydrant Testing for Model Calibration


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Name AWWA Distribution Systems Symposium, 2010

Location National Harbor MD USA



n/a n/a n/a n/a n/a

Page 1 of 2


Literature Review Historic Overview Definitions Timeline Hydrant Floe Test

Steady State EPS Micro-calibration Macro-calibration


An overview of the water distribution modeling followed by review of case studies of hydrant testing used for model calibration.



Page 2 of 2




Year Month Day


Field No. 3 Author


Primary Shen Hailiang

Secondary McBean Edward

Tertiary

Additional


Hydraulic calibration for a small water distribution network


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1545 – 1557

Page 1 of 2


Hydraulic calibration Sensitivity analysis Genetic algorithm Monte Carlo simulation EPANET

C-factor Optimization


Procedures utilized for hydraulic model calibration for the C-Town network, which is the first step prior to a model being useful for operation and maintenance, and water quality model construction, is described. For the C-Town network as provided by BWCN, seven groups of parameters are identified, namely, pipe roughness, elevation, leakage coefficient, pump curve, base demand, pattern value, and pump and valve control. The calibration is formulated as an optimization problem, aimed at minimizing the discrepancy between observed and simulated data. A toolkit is developed within VC++ 2008 Express to solve the optimization problem, by employing a flexible genetic algorithm library GAlib as the optimization engine, and EPANET as the hydraulic solver. Monte Carlo simulation is applied for sensitivity analyses to identify sensitive parameters to feed the calibration process. It is shown the seven groups of parameters have similar sensitivity and all feed to calibration process. The tank levels are relatively well calibrated, comparing with the pump station flow rates.


This paper was presented at the 2010 Water Distribution Systems Analysis (WDSA) conference in Tucson, Arizona, USA. Paper describes procedures used for automated and objective model calibration. The authors describe a “calibration tool kit” developed for model calibration that uses EPANET as the hydraulic solver and GAlib as the optimization engine. These two are then linked within VC++208 Express. The tool kit is developed for general use but is applied to a site specific water distribution system as a case study.


Shen, H, and McBean, E., "Hydraulic calibration for a small water distribution network,” In: Proceedings, Water Distribution System Analysis 2010, September 12–15, 2010, Tucson, Arizona, p. 1545–1557.

Page 2 of 2




Year Month Day

2010 September

Field No. 3 Author


Primary Quiroz-Centeno Alberto

Secondary Parault Patrick

Tertiary Carlese James

Additional


Water Quality Calibration of New York City’s Water Distribution System Model


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Conference Paper

Journal Paper

Technical Report



X


Name ASCE – Water Distribution Systems Analysis Symposium

Location Tucson AZ USA



Page 1 of 2


Water distribution system Hydraulic model Calibration Water quality Tracer study


The New York City Department of Environmental Protection (NYCDEP) has developed a water distribution system model to meet the growing need to quantify current or planned changes in its water supply system. The model simulates multiple parameters for applications that include estimating hydraulic and water quality impacts of new water sources and the activation of new conveyance tunnels. The model includes representation of major system components including: three aqueducts, two balancing reservoirs, two underground tanks, three deep-rock tunnels, groundwater wells and tanks, system valves, trunk mains and some distribution mains. Flow and pressure data were used to hydraulically calibrate the model. A fluoride tracer study was performed to verify the model’s ability to estimate water travel time through the system. The study was conducted in two phases: Phase I monitored the cessation of fluoride addition while Phase II tracked the resumption of fluoride addition. The model was used to simulate the resumption of fluoride addition. Measurements from 21 city-wide sampling sites in Phase II were used to evaluate model results. The model matched fluoride breakthrough times to the sampling sites to within five hours on average. In addition to the favorable match with breakthrough time, the model exhibited good agreement with the measured fluoride pattern – a product of the diurnal interactions between the reservoirs and aqueducts. The hydraulic and water quality simulations match measured field values to within the performance expectations of a planning level model. This paper summarizes the model attributes, development of the tracer study, and model results.



Page 2 of 2




Year Month Day

2010

Field No. 3 Author



Secondary

Tertiary

Additional


Calibration of Water Distribution System Hydraulic Models – Concepts, Methods, and Examples


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X


Name Lambert Academic Publishing

Location Saarbrucken Germany 66123 EU



9 Chapters 274 Total

Page 1 of 2


Model Calibration Optimization Genetic Algorithm Parameter Uncertainty Statistics

Sampling Design Transients Uniqueness Steady-State EPS


Back Cover:

Hydraulic simulation models are frequently used nowadays for the planning and operational management of water distribution systems. To be effectively used, these models need to be calibrated first. During the calibration process the unknown model parameter values are determined with the aim to achieve as best as possible match between the simulated model predictions and the corresponding measurements obtained in the field. Traditionally, calibration was, and, unfortunately, still is in some cases, treated as a manual task. However, as this book (based on the author’s PhD thesis) will show, better results can be achieved if calibration of the analysed hydraulic model is formulated and solved as an optimisation problem.


Solid coverage of the model calibration problem couched as an optimization problem. Major concepts are reinforced with case examples.


Kapelan, Z. (2010), “Calibration of Water Distribution System Hydraulic Models”, LAP Lambert Academic Publishing, ISBN 978-3-8383-5341-8.

Page 2 of 2




Year Month Day

2010 01 20

Field No. 3 Author


Primary Speight Vanessa

Secondary Khanal Nabin

Tertiary Savic Dragan

Additional Kapelan Zoran


Guidelines for Developing, Calibration, and Using Hydraulic Models


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Name Water Research Foundation

Location Denver Colorado 80235 USA



4018 3 49 - 68

Page 1 of 2


Guidelines IDSE Roughness Demand Allocation Water Quality

Data Quality Disinfection By-Products Criteria Trial-and-Error Optimization


The goal of the overall document is to provide concise, comprehensive, and user-friendly guidance on the development, calibration, and application of hydraulic models for distribution systems. This abstract focuses on the calibration aspects of these guidelines (specifically Chapter 3, pages 49 though 68). Throughout the evolution of modeling, the water industry has struggled with defining appropriate calibration techniques and standards. This struggle has been complicated by the system-specific nature of modeling and the wide range of model uses, each requiring different degrees of certainty in the outcome.

Chapter 3 covers the topic of model calibration, with descriptions of current practices and lessons learned from participating utilities. This chapter provides practical advice on calibration data collection and on calibration techniques, including several examples of model output and suggested options to improve goodness-of-fit. Summaries of case studies related to model calibration are also provided including results on categories of calibration data, methodologies, parameters, criteria, and frequency that utilities use during the calibration process.

Typical hard and soft model input data are summarized which defines the data that can be and should be field confirmed and the data which is difficult to field confirm and can be modified in the calibration process to better match observed conditions versus model results. Depending on how a utility operates their facilities (e.g. automated versus manual), the ability to reach a goodness-of-fit can change drastically. Calibration guidance including minimum model requirements and case studies on Initial Distribution System Evaluations (IDSE) using hydraulic models is included. Case studies involving tracer tests and demand allocation are provided in detail regarding IDSEs.


From the document’s Executive Summary: The findings of this project will provide a baseline for objective evaluation of distribution system models. Two major results from this project will benefit both experienced and beginner modelers. The first is a compilation of practical information about the different aspects of modeling that reflects the experience of modelers with real-world data and applications. Second, to tie together the practical modeling information and provide guidance for modelers, a methodology for developing a modeling plan was created. This methodology provides a step by step process for a utility to use in evaluating available data and planning for a modeling project.


AWWA Water Research Foundation. “Chapter 3- Model Calibration,” "Guidelines for Developing, Calibrating, and Using Hydraulic Models." Denver, CO, January 2010, Chapter 3, pp 49-68, 2010.

Page 2 of 2




Year Month Day

2010

Field No. 3 Author


Primary Alvisi Stefano

Secondary Franchini Marco

Tertiary

Additional


Pipe roughness calibration in water distribution systems using grey numbers


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X


Name IWA Publishing, Journal of Hydroinformatics

Location London UK



12 4 424 – 445

Page 1 of 2



Simulation Calibration Grey numbers Hydraulic simulator First-order Taylor series

expansion


This paper presents a procedure based on the use of grey numbers for the calibration (with uncertainty) of pipe roughness in water distribution systems. The pipe roughness uncertainty is represented through the grey number amplitude (or interval). The procedure is of a wholly general nature and can be applied for the calibration (with uncertainty) of other parameters or quantities, such as nodal demands. In this paper, for the purpose of roughness calibration, a certain number of nodal head measurements made under different demand conditions is assumed to be available at different locations (nodes); all other topological and geometric characteristics of the system are considered to be known exactly. The general approach to pipe roughness calibration (taking account of uncertainty) focuses on identifying the grey roughness values which produce grey head values at the measuring nodes such as to encompass the observed values grouped on the basis of the different demand scenarios and, at the same time, have as small an ‘amplitude’ as possible. The proposed procedure was applied to two synthetic case studies and to one real network. The tests on the synthetic case studies show that the proposed procedure is able to correctly solve the inverse problem, i.e. it can identify the known grey roughness numbers even when they overlap; the same applies when the known grey roughness numbers collapse into known white roughness numbers. The test on the real case offers the possibility of highlighting the potentials of the procedure when applied within a context where measurement errors and other uncertainties are present. The procedure entails computing times that may become lengthy. However, it is possible to reduce these computing times considerably by replacing the hydraulic simulator—to which a number of calls must be made during the calibration procedure (for objective function evaluation)—with an approximation based on a first-order Taylor series expansion. This approach introduces acceptable approximations within the context of the problem considered.


Paper presents a methodology using “fuzzy” or “grey numbers” to estimate C-Factor (roughness) as the calibration parameter. Two synthetic (hypothetical) distribution systems are presented using the proposed approach and one “real world” water distribution system is analyzed. EPANET is used as the hydraulic simulator. An additional analysis is presented that uses a first-order Taylor series expansion as the simulator.


Alvisi, S, and Franchini, M., "Pipe roughness calibration in water distribution systems using grey numbers,” Journal of Hydroinformatics, Vol. 12, No. 4, 2010, pp 424–445.

Page 2 of 2




Year Month Day

2010

Field No. 3 Author


Primary Alvisi Stefano

Secondary Franchini Marco

Tertiary

Additional


CALIBRATION AND SENSITIVITY ANALYSIS OF THE C-TOWN PIPE NETWORK MODEL


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NA NA 1573 - 1584

Page 1 of 2


Water distribution systems

Calibration Sensitivity analysis Pipe networks Monte Carlo method


This paper presents a methodology for both the calibration and sensitivity analysis of the hydraulic simulation model relative to the C-Town distribution system included in the framework of the Battle of Water Calibration Networks. As regards the calibration, an automatic process based on the SCE-UA algorithm was initially performed then followed by a manual refinement. The subsequent sensitivity analysis allows for the quantification of the effect of the calibrated model parameters on the output variables of the hydraulic model; this latter analysis was performed following a technique based on the Monte Carlo-Latin Hypercube approach. The application of the calibration process leads to a set of parameters which enables the hydraulic model to properly reproduce the observed measures both in fire flow test conditions and in extended period simulation (one week). The sensitivity analysis highlights which of the input variables (pipe roughnesses, minor valve losses, pump speeds) most affect the output variables (reservoir water levels, node pressures and pipe flows), thus providing information useful within the context of system design, rehabilitation and real-time management.


Paper presents a methodology using “fuzzy” or “grey numbers” to estimate C-Factor (roughness) as the calibration parameter. Two synthetic (hypothetical) distribution systems are presented using the proposed approach and one “real world” water distribution system is analyzed. EPANET is used as the hydraulic simulator. An additional analysis is presented that uses a first-order Taylor series expansion as the simulator. Similar method to: Alvisi, S, and Franchini, M., "Pipe roughness calibration in water distribution systems using grey numbers,” Journal of Hydroinformatics, Vol. 12, No. 4, 2010, pp 424–445.


Alvisi, S. and Franchini, M. (2011) Calibration and Sensitivity Analysis of the C-Town Pipe Network Model. Water Distribution Systems Analysis 2010: pp. 1573-1584. doi: 10.1061/41203(425)140

Page 2 of 2




Year Month Day

2010

Field No. 3 Author


Primary Asadzadeh Masoud

Secondary Tolson Bryan

Tertiary McKillop Robert

Additional


A TWO STAGE OPTIMIZATION APPROACH FOR CALIBRATING WATER DISTRIBUTION SYSTEMS


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NA NA 1682 - 1694

Page 1 of 2


Simulation Calibration Water distribution Optimization Coefficients


BWCN is a competition for calibrating pipe roughness coefficients and demand pattern multipliers of C-Town Water Distribution System (WDS) to measured SCADA (hourly tank levels and pump flows) and fire flow test data in a 1-week operation. In a pre-calibration step, quality of the data is assessed, base demands for the fire flow tests are estimated, by mass balance, and pipes are grouped and their nominal values and variation range are determined. In this study, the calibration problem is solved in two stages, each of which tunes a portion of decision variables (DVs) that significantly impact the corresponding objectives while other DVs are set to their nominal (or calibrated) values. Dynamically Dimensioned Search based optimization algorithms are used in both stages because the default algorithm parameter setting is robust. Stage-1 aims to fit the fire flow test measurements that are highly affected by pipe roughness coefficients. Also, demand pattern multipliers for hour-1 SCADA must be calibrated in this stage because the base demand during the fire flow tests is roughly the same as those in hour 1. Ideally, a single solution must minimize the calibration error for all the measurements simultaneously. However, since no perfect model and/or data set exist, objective functions (error metrics) are usually in conflict. Therefore, this stage is set up as a bi-objective optimization problem to minimize the calibration error in simulating fire flow test measurements versus simulating hour-1 SCADA measurements. At the end of this stage, multi-criteria decision making is utilized to select candidate solutions to be evaluated in stage-2. In stage-2 demand pattern multipliers are calibrated to fit the SCADA (tank levels and pump flows). The WDS model performance in each hour is independent from subsequent hours; therefore, stage-2 is set up to calibrate demand pattern multipliers hour by hour starting from the hour 2 to 168 (1 week). All candidate solutions from stage-1 are evaluated in stage-2 and one of them is selected as the final solution to the C-Town calibration problem based on multi-criteria decision making. On average, the final calibrated model estimates static pressure, fire flow tests, tank levels and pumping flow rates of SCADA to within 3.5%, 1.5%, 1.0%, and 2.5% of the measured data respectively.


The paper presents a bi-level optimization approach for water distribution systems calibration, implemented on C-Town.


Asadzadeh, M., Tolson, B., and McKillop, R. (2011) A Two Stage Optimization Approach for Calibrating Water Distribution Systems. Water Distribution Systems Analysis 2010: pp. 1682-1694. doi: 10.1061/41203(425)148

Page 2 of 2




Year Month Day

2010 September

Field No. 3 Author


Primary Bros Christopher M.

Secondary Kalungi Paul

Tertiary

Additional


Battle of the Water Calibration Networks – MWH UK


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Name American Society of Civil Engineers: 12th Annual Conference on Water Distribution Systems Analysis




1507 - 1523

Page 1 of 2



Calibration Hydraulic models


The MWH UK team members have applied their experience of building and calibrating water network models in the BWCN task to rapidly construct and calibrate the C-Town model using trial-and-error methodology. The main aim has been to complete the calibration exercise in a reasonable timescale, using engineering judgement to deal with data quality issues and interpretation of modelling results. The belief is that a good compromise between quality and effort should yield results that compare well with more labour intensive or computationally intensive procedures. The team effort has been divided between construction, calibration and quality assurance (QA) using our company techniques for quality control and reporting. The calibrated C-Town model has been produced by force fitting much of the input data to the model to produce an internally consistent solution using MWHSoft's InfoWater software available at http://www.mwhsofi.com/page/p_download/down_infowater70.htm. Several assumptions have been made without a chance of verifying them with the organisers. An *.inp file of the calibrated network for an Extended Period Simulation (EPS) of 168 hrs has been produced using EPANET (version 2.00.12) available at http://www.epa.gov/nrmrl/wswrd/dw/epanet.html. The C-Town model is internally consistent and provides a good match against the SCADA data provided. The calibration effort needed to achieve this solution was less than 4 days' input by the combined team. This is about 10% of the normal level of effort for a real world C-Town.



Christopher M. Bros and Paul Kalungi (2011) Battle of the Water Calibration Networks-MWH UK. Water Distribution Systems Analysis 2010: pp. 1507-1523. doi: 10.1061/41203(425)135

Page 2 of 2




Year Month Day

2010 September

Field No. 3 Author


Primary Burd Richard

Secondary Zazula-Coetzee Boguslawa

Tertiary Belrain Teddy

Additional


Battle of the Water Calibration Networks (BWCN)


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name American Society of Civil Engineers: 12th Annual Conference on Water Distribution Systems Analysis




1524 - 1531

Page 1 of 2



Calibration United Kingdom Errors


This paper details how a water network model can be calibrated using very limited trial and error and no complex specialized mathematical software. This process is used regularly to calibrate models for Veolia Water in the UK.



Page 2 of 2




Year Month Day

2010

Field No. 3 Author


Primary Chang Kui

Secondary Gao Jinliang

Tertiary Qu Shaojian

Additional Yuan Yixing


Research on Water Distribution Network Calibration Using Heuristics Algorithm and Pipeline Resistance Coefficient Empirical Model


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Journal Paper

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X



Location



1645 - 1651

Page 1 of 2



Research Hydraulic models Algorithms Coefficients


The water network was calibrated by two steps. The nodal demand was calibrated firstly, and then the pipeline resistance coefficient was calibrated. The results of steady state, fire flow state and expended period simulation were selected for model calibration. The tank level and the pump station flow were selected as the calibration object. For fire flow state, the node demand and nodal pressure were used. For the first step, the pipeline resistance coefficient calculated by empirical model which was built on the basis of large number of field test data for all kinds of pipes, and equivalent flow rate was introduced in order to accelerate nodal demand calibration. After then, pipeline resistance coefficient was calibrated at the base of nodal demand calibrating result and the requirement of objective function converging was more higher than the first step. The heuristics algorithm was applied on water network calibration.



Kui Chang, Jinliang Gao, Shaojian Qu, and Yixing Yuan (2011) Research on Water Distribution Network Calibration Using Heuristics Algorithm and Pipeline Resistance Coefficient Empirical Model. Water Distribution Systems Analysis 2010: pp. 1645-1651. doi: 10.1061/41203(425)145

Page 2 of 2




Year Month Day

2010 September 12 - 15

Field No. 3 Author


Primary Diao Kegong

Secondary Zhou Yuwen

Tertiary Li Ji

Additional Zilong Liu


Battle of the Water Calibration Networks (BWCN): A Component Status Changes Oriented Calibration Method for Zonal Management Water Distribution Networks


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X


Name 12th Annual Conference on Water Distribution Systems Analysis (WDSA), ASCE

Location Tucson Arizona USA



1629 - 1644

Page 1 of 2


BWCN Calibration Hydraulic modeling SCADA Water distribution

network

Water distribution system


Calibration is the prerequisite for a hydraulic model of water distribution system to be utilized in practice. Given the case-specific feature of model calibration, this paper introduces a method that is oriented by component status changes in zonal management water distribution systems. This method is specified for zonal systems in which the operation of every zone could be framed to a stable periodical performance based on control routines, which would not be affected substantially by condition variation in other zones or the effects could be deduced. The principle of this methodology is to identify scenarios with status changes of several crucial components in water distribution networks which give rise to significant effects on hydraulic performance at least in a certain region of the water distribution system. After, those scenarios could be used for calibration of both pipe roughness and demand pattern multipliers with measured data (e.g. SCADA data) as constraints. For verification, this methodology is applied to the case study of "The Battle of the Water Calibration Networks (BWCN)" based on understanding of the system features and behaviors according to available data and corresponding statistical analysis. The final outcomes demonstrate that this approach could reach acceptable results more efficiently if characteristics of the studied system could be well identified.


Both pipe roughness and demand pattern multiplier were adjusted to calibrate the network. Different hydraulic scenarios were generated by changing the status of crucial components in the water distribution networks.


Diao, K., Zhou, Y., Li, J., and Liu, Z. (2010) Battle of the Water Calibration Networks (BWCN): A Component Status Changes Oriented Calibration Method for Zonal Management Water Distribution Networks. 12th Water Distribution Systems Analysis 2010: pp. 1629-1644. doi: 10.1061/41203(425)144

Page 2 of 2




Year Month Day

2010 September

Field No. 3 Author


Primary Johnson Joshua

Secondary Ghimire Santosh

Tertiary Barkdoll Brian

Additional


Flow-Sequential Sector-Specific Lumped Algorithm for Water Network Calibration


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name 12th Annual Conference on Water Distribution Systems Analysis (WDSA), ASCE




1585 - 1598

Page 1 of 2


BWCN Calibration Flow sequential sector-

specific lumped algorithm SCADA

Water Distribution Networks



As part of the Battle of the Water Calibration Networks (BWCN) an algorithm termed the Flow sequential Sector-specific Lumped Algorithm (FSL) is employed to determine a set of roughness values for each pipe and the user demands at every junction of the system used for the contest. The FSL algorithm for roughness determination lumps all pipes in each pressure zone (similar to given district metering areas) together and alters the roughness values proportionately as a whole. Fine tuning with the pipes adjacent to the known pressure nodes is the final step. This is done iteratively from the furthest upstream pressure zone to the furthest downstream pressure zone and repeated until a satisfactory agreement between predicted and measured value is attained. Age-dependent roughness values are initially assigned according to literature values. The network in the demand calibration phase of the study was handled as a whole. Demand values based on the monthly demands were provided, and a common residential diurnal pattern found in the literature was assigned as an initial value for the extended period simulation. The demand pattern was adjusted for select hours to calibrate the network to match the SCADA data. This was followed by the fine tuning of the demand pattern values. It was found that the calibration process resulted in mean absolute relative errors in pressure of approximately 0.1 when adjusting roughness values for calibration with fire flow tests and 0.21 for discharge and tank level values in the adjustment of demand values.


Both pipe roughness and nodal demands are adjusted to calibrate a water distribution network using the SCADA data. The algorithm is termed Flow sequential sector-specific lumped algorithm and was a part of BWCN.


Johnson, J., Ghimire, S., and Barkdoll, B. (2011) Flow-Sequential Sector-Specific Lumped Algorithm for Water Network Calibration. Water Distribution Systems Analysis 2010: pp. 1585-1598. doi: 10.1061/41203(425)141

Page 2 of 2




Year Month Day

2010 September

Field No. 3 Author


Primary Saldarriago Juan

Secondary Nieto Laura

Tertiary Navarro Ivonne

Additional Nino Gesar


Calibration Process of a Chlorine Decay Model: The Case Study of Bogota


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name ASCE – Water Distribution Systems Analysis Symposium – 2010




Page 1 of 2


Water distribution Hydraulic model Calibration Water quality Sampling points

Trunk networks Chlorine decay


Water quality decay is an issue that negatively affects water supply companies’ credibility. Therefore, they are required to implement policies that maintain water quality within acceptable levels; especially, when operation changes are made to the network. In order to do that, the use of water quality modeling as a process to understand the needs of the system is very useful. However, it requires a calibration process to guarantee that the results obtained from the model accurately represent what is occurring in the system. This paper presents a case study in which an automated methodology for the calibration of a water quality model based on a route followed by the water and the characteristics of the pipes that comprise it is tested in Bogotá’s trunk network. Then, the process to develop the water quality model, taking into account the characteristics of the water quality sources and mixing models in storage tanks, is presented. The methodology was effective by accurately representing the process in the network, allowing the establishing of zones where the chlorine decay was significant, and determining the factors that affect its decay. As a result of this study, the Water Supply and Sewer Company of Bogotá (EAAB, Spanish acronym) has a calibrated water quality model used for different purposes such as the understanding of chlorine decay in district meter areas (DMAs) regardless of the operation scheme implemented on the trunk network. This facilitates establishing the optimal location for quality measurements.



Page 2 of 2




Year Month Day


Field No. 3 Author


Primary Piller Olivier

Secondary Van Zyl Jakobus E.

Tertiary Gilbert Denis

Additional


DUAL CALIBRATION FOR COUPLED FLOW AND TRANSPORT MODELS OF WATER DISTRIBUTION SYSTEMS


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name ASCE




Page 1 of 2


Water Distribution System Calibration Optimization Levenberg-Marquardt


The operation of drinking water supply networks is generally assessed using two complementary computer models. Firstly, the flow rates in the system are predicted from a hydraulic model with given input parameters and a network graph. Then the calculated pipe velocities are used in a transport reaction solver to determine various indicators for water quality, such as residence times, source tracings, and disinfectant concentrations. High parameter uncertainties require parameter estimations to be made to improve the predictions of the two coupled models.

The objective of this paper is to assess if a dual calibration for these coupled models is possible through the use of a gradient method. Based on field data measurements, such as tank levels, pressures, flow rates and chlorine concentrations, a weighted least-squares problem is defined for an over-determined system to minimize the residuals between observed and model values. A direct solution based on the Levenberg-Marquardt method is proposed.

The dual calibration was tested on two real networks and was shown to be effective even with inevitable unexpected circumstances. The parameter uncertainty, or even the observability, was found to be strongly linked to measuring device placement. Selecting measuring devices that are more sensitive may drastically improve the conditioning of the calibration problem.


This is a highly theoretical paper dealing with the application of transport modeling to the calibration process. Very interesting paper, but I believe it is too theoretical for our purposes.


Page 2 of 2




Year Month Day


Field No. 3 Author


Primary Suroso Irene

Secondary Boissevain Polly

Tertiary

Additional


Using tracer field testing for model calibration: A case study


Book Reference

Conference Paper

Journal Paper

Technical Report



X






732 – 746

Page 1 of 2


Hydraulic model calibration

Water quality modeling Water age Tracer test Fluoride

SCADA Extended period

simulation Water treatment plant Case study


Use of results from a tracer field data collection program can add great value to dynamic calibration of a hydraulic model, particularly for a model to be used for water quality analysis. Initial planning for the study and selection of the tracer chemical are very important steps prior to field data collection efforts. A well organized sampling program will optimize the project schedule and budget. This paper discusses key issues associated with developing a field tracer sampling program and presents a case study for a fluoride tracer sampling program, including planning considerations for the field testing, such as selection of monitoring locations, tracer considerations, and data collection protocols. Results from the study enable Roseville to use the calibrated water quality model to evaluate water exchange through intertie connection with a neighboring utility resulted Roseville to divert the return supply from neighboring utility directly to storage tank to further blending return water to achieve desire fluoride concentration. The water quality model also helped Roseville to comply with drinking water regulations by completing water age study.


This paper was presented at the 2010 Water Distribution Systems Analysis (WDSA) conference in Tucson, Arizona, USA. Paper describes procedures used for conducting a tracer test of the City of Roseville, California’s water distribution system using fluoride as the tracer. Field data from the fluoride tracer test are then compared against modeling results.


Suroso, I, and Boissevain, P., "Using tracer field testing for model calibration: A case study,” In: Proceedings, Water Distribution System Analysis 2010, September 12–15, 2010, Tucson, Arizona, p.732–746.

Page 2 of 2




Year Month Day

2011 September

Field No. 3 Author



Secondary --- ---

Tertiary --- ---

Additional --- ---


Is the Model Calibrated?


Book Reference

Conference Paper

Journal Paper

Technical Report



X X


Name AWWA – DSS 2011

Location Nashville TN USA



Page 1 of 2


Standards Management


Models exist as decision support tools and the acceptability of calibration depends on whether they can be used with confidence to support decision making. The true test of whether a model requires additional calibration lies in the rule: “Is the cost of additional calibration greater than the benefits that will accrue from additional calibration?” If the answer is “yes”, then additional calibration is justified; if the answer is “no”, then the model is adequately calibrated for that purpose.

Unfortunately, converting the rule in the above paragraph into numerical criteria is complicated by the many dimensions of the model. A model may be well calibrated for use in master planning but do a poor job in predicting chlorine decay. Conversely, a model may do an excellent job in describing system operation but may fail to adequately model fire flows in one portion of the system. Add in the problem that field data used for calibration is often inaccurate or incomplete and in some cases the model is being used to calibrate the field data. Criteria such as “+/- 5 psi” are not very useful when the model is being used for estimating water age or predicting energy use. No model is ever perfectly calibration for all purposes. The answer to the “Is the model calibrated?” question does not deserve a yes or no answer but rather begs for answer with respect to the degree of agreement for a given purpose in a given portion of the system for a particular set of field data and boundary conditions.


Instead of posing standards in terms of percent or absolute error, it may make more sense to establish best modeling practices that should be implemented whenever model development is completed. These include

• There is an understanding of what the model is to be used for.

• Data collected for calibration is of sufficient accuracy and completeness and measures the right properties of the system.

• There is an understanding of the tradeoffs between the cost of calibration and the benefits.

• There is a commitment to follow up and understand (and hopefully correct) any disagreement between the model and field data.

• There are reasonable expectations as to agreement.

• There is an understanding that the model may need further validation/calibration if it is used at a later time for a different purpose.


Page 2 of 2




Year Month Day

2011 June 12 – 16

Field No. 3 Author



Secondary

Tertiary

Additional


Distribution system hydraulic calibration—Methodologies and best practices


Book Reference

Conference Paper

Journal Paper

Technical Report



X






Page 1 of 2


Micro-calibration Macro-calibration Calibration statistics Best practices EPS Calibration

SCADA Hydrant testing C-factors Flow testing Validation

Water age Source trace Documentation


This document is a presentation made at the 2011 American Water Works Association (AWWA) Annual Conference & Exposition, June 12–16, Washington, DC. The presentation describes what is model calibration, differences between macro- and micro-calibration, approaches to hydraulic steady-state and extended period simulation (EPS) calibration, review of calibration statistics, and best practices.


This presentation is an overview. It does provide some very good (but limited) references on model calibration.


Edwards, J. “Distribution system hydraulic calibration—Methodologies and best practices.” In: Proceedings, American Water Works Association Annual Conference & Exposition 11, June 12–16, 2011, Washington, DC.

Page 2 of 2




Year Month Day

2011 January

Field No. 3 Author


Primary Kang Doosun

Secondary Lansey Kevin

Tertiary

Additional


Demand and Roughness Estimation in Water Distribution Systems


Book Reference

Conference Paper

Journal Paper

Technical Report



X



Location



137 1

Page 1 of 2


Uncertainty analysis Weighted least squares Calibration Demand estimation Sequential estimation


To provide more accurate estimates and account for associated uncertainties, a parameter estimation methodology for water distribution systems (WDSs) that combines demand and parameter estimation processes is proposed. A two-step sequential method for dual estimation of demand and roughness coefficient is presented based on a weighted least-squares scheme using field measurements of pipe flow rates and nodal pressure heads under multiple demand conditions. The uncertainties in the estimated variables and resulting nodal pressure predictions are quantified in terms of confidence limits using the first-order second moment method. The algorithm is applied to two network systems including a midsized real WDS. The two-step sequential model provides accurate and precise estimates while joint estimation provides poor estimates.



Kang, D. and Lansey, K. (2011). ”Demand and Roughness Estimation in Water Distribution Systems.” J. Water Resour. Plann. Manage., 137(1), 20–30.

TECHNICAL PAPERS

Page 2 of 2




Year Month Day

2011 December

Field No. 3 Author


Primary Giustolisi O

Secondary Berardi L

Tertiary

Additional


Water distribution network calibration using enhanced GGA and topological analysis


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name IWA Publishing

Location London UK



13 4 4 621 - 641

Page 1 of 2


Algorithm Calibration Global gradient Simulation Water Distribution

Networks



The calibration of hydraulic models of water distribution networks (WDN) is of preeminent importance for their analysis and management. It is usually achieved by solving a constrained optimization problem based on some priors on decision variables and the demand-driven simulation of the entire network, given the observations of some hydraulic status variables (i.e. typically nodal heads and sometimes pipe flows). This paper presents a framework to perform the calibration of pipe hydraulic resistances considering two main issues: (i) the enhancements of WDN simulation models allowing us to simplify network topology with respect to serial nodes/trunks and/or to account for a more realistic representation of distributed demands and (ii) a different formulation of the calibration problem itself. Depending on the available measurements, the proposed calibration strategy reduces the hydraulic simulation model size and can permit the decomposition of the network. On the one hand, such a procedure allows for numerical and computational advantages, especially for large size networks. On the other hand, it allows a prompt analysis of observability of calibration decision variables based on actual observations and might help identifying those pipes (i.e. hydraulic resistances) which are more important for the whole network behaviour.


Enhanced Global Gradient Algorithm is used for calibration of hydraulic resistances that allows considerable reduction of calibration problem due to elimination of serial nodes and helps in identifying pipes which are of most importance to describe global hydraulic network behavior.


Guistolisi, O., and Berardi, B. (2011). "Water distribution network calibration using enhanced GGA and topological analysis", J. of Hydroinformatics, 13(4), 621-641.

Page 2 of 2




Year Month Day

2011 September

Field No. 3 Author


Primary Perez Ramon

Secondary Nejjari Fatiha

Tertiary Puig Vicenc

Additional Quevedo, J.; Sanz, G.; Cuguero, M. Peralta, A.


Study of the Isolation of Leaks in a Network Depending on Calibration of Demands


Book Reference

Conference Paper

Journal Paper

Technical Report



X



Location London UK



Page 1 of 2


Simulation Sensitivity Uncertainty Epanet Steady-State

Transient Roughness Telemetry Noise Validity


Using the simulation models a methodology was developed for leakage detection and localisation in a water distribution network [4]. Such methodology is based on fault detection and isolation techniques. Sensitivity matrix of pressures to leaks [8] is generated using simulation models [1]. Such models are available in water companies. The methodology showed promising results but two main issues appeared. Calibration in models and precision in sensors was required. Investment in sensors could be afforded [6] as long as models were well calibrated enough. The main uncertainty in models lies on demands. This paper presents a study of the effect of an improvement in demand calibration on isolation of leaks. The aim is to quantify the return of an effort in calibrating in terms of leak detection one of the main issues in water industry.



Page 2 of 2




Year Month Day

2011 September

Field No. 3 Author


Primary Prasad T. Devi

Secondary Scholz Miklas

Tertiary Tota-Maharaj Kiran

Additional


Water Distribution Network Calibration using DE-MC


Book Reference

Conference Paper

Journal Paper

Technical Report



X



Location London UK



Page 1 of 2


Estimation Parameters Uncertainty Optimization Genetic Algorithm

Roughness Diagnostic Pressure Measurement Flow Measurement Model Error

Steady-State Extended Period


Water distribution system (WDS) network models are widely used by planners, water utility personnel, consultants and many others involved in analysis, design, operation or maintenance of water distribution systems. Estimation of network model parameters is a difficult but an essential step in the use of these models. Although some models have been proposed to estimate uncertainty associated with model parameters, most of these models either use complex derivative based methods such as first-order second moment (FOSM) method or use computationally intensive methods such as shuffled complex evolution metropolis (SCEM-UA). This paper presents a modified differential evolution Markov chain (DE-MC) algorithm to calibrate water distribution network models. In addition to giving both model parameters and associated uncertainty in a single run, the algorithm is simple to understand and computationally less intensive. The calibration problem was formulated as determining the network model parameters such that the best match between measured and predicted data is obtained. The proposed model was applied to calibrate two well-known examples from literature, namely, the Anytown network and the C-Town network. The network calibration parameters obtained, when input into the CTown hydraulic model, produced reasonably good match between the predicted and the observed tank water levels and pump station flows.


Using modified differential evolution Markov chain (DE-MC) algorithm to calibrate network models.


Page 2 of 2




Year Month Day

2011 September

Field No. 3 Author


Primary Vassiljev Anatoli

Secondary Koppel Tiit

Tertiary Saare Arvo

Additional


Sensitivity of Calibration Results to Uncertainties in Input Data: Case of Operational Water Distribution System


Book Reference

Conference Paper

Journal Paper

Technical Report



X



Location London UK



Page 1 of 2


Uncertainty Pressure Measurement Flow Measurement Optimization Roughness

Hazen-Williams Darcy-Weisbach Parameters EPANET


The data used for calibration of a water distribution system (WDS) model contain uncertainties. These uncertainties include, in particular, errors in measurements of pressures and water flows, errors in demands, demands pattern, erroneous node elevations, limited sample size, etc. Moreover, some assumptions influence the results of calibration as well. For example, water inflow into WDS is often higher than sum of registered demands. This difference between water inflow and demands includes real and apparent leakages with unknown proportionality. The results of calibration depend on the assumed proportion between real and apparent leakages and on the assumed distribution of them over WDS. Weight coefficients, assumed for pressure and flow measurements in objective function, used in the optimization procedure, are another assumption influencing calibration results. WDS models contain also patterns of demands. But real demands are usually measured for quite long periods of time (e.g. a month) and give information only on the average base demand. Experience in the calibration of WDS models showed large uncertainties of hourly demands estimated by this manner. The effect of these types of uncertainties on calibration results has been considered in the paper.


Quality of measurement key for calibration. Frequent measurements under different conditions. If grouping accomplished by age, less errors in calibration due to other factors (location of leakage, unaccounted demand, etc).


Page 2 of 2




Year Month Day


Field No. 3 Author



Secondary

Tertiary

Additional


Toward A Rational Design For Fireflow Tests For Model Calibration


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name 14th Water Distribution Systems Analysis Conference – Engineers Australia

Location Adelaide Australia



Page 1 of 2


Hydraulic model Fireflow tests Closed valves


Fireflow tests can be used as part of a program for calibrating steady state water distribution system hydraulic models. Though there are standard methods available for conducting fireflow tests to assess the ability of a distribution system to deliver adequate fireflow, there is virtually no guidance available in the literature that addresses the design issues associated with the use of fireflow tests in model calibration. The issues associated with designing fireflow tests for model calibration are discussed and a framework methodology for evaluating the effectiveness of fireflow tests for calibration and for selecting locations within the distribution system for performing fireflow tests is presented. An example of the use of fireflow tests for identifying closed valves is presented employing the concept of “covering” valves by conducting fireflow tests that will reflect the presence of closed valves.


A methodology framework for designing fireflow tests to be used in calibrating a steady-state water distribution system hydraulic model is described. Issues and previous work associated with designing fireflow tests for model calibration are discussed and a framework methodology for evaluating the effectiveness of fireflow tests for calibration and for selecting locations within the distribution system for performing fireflow tests is presented. The criteria employed in designing fireflow tests is the ability of fireflow tests to identify the likely presence of unexpected closed valves. The methodology uses the concept of “covering” valves by conducting fireflow tests that will reflect the presence of closed valves, i.e., a valve is considered as “covered” if a fireflow test would suggest the presence of an unexpected closed valve. Such a method could be embedded in a optimization framework to determine optimal fireflow test designs – i.e., which hydrants to flow and which hydrants to use to measure residual pressures. The objective in the optimization program could be: (a) find the fewest number of flow tests that will cover all valves; or (b) with a fixed budget that will allow only a limited number of fireflow tests, find the combination of flowing hydrants and residual hydrants within your budget that results in the largest number of valves being covered. A small example of the methodology is demonstrated on a EPANET model of the hypothetical SmallWater distribution system.


Grayman, W.M. (2012). “Toward A Rational Design For Fireflow Tests For Model Calibration”. 14th Water Distribution Systems Analysis Conference. Engineers Australia. Adelaide, Australia.

Page 2 of 2




Year Month Day

2012 September ---

Field No. 3 Author


Primary Ostfeld Avi

Secondary Salomons Elad


Additional


“Battle of the Water Calibration Networks”


Book Reference

Conference Paper

Journal Paper

Technical Report



×


Name ASCE




138 5 523 - 532

Page 1 of 2



Calibration Model Optimization Network


Calibration is a process of comparing model results with field data and making the appropriate adjustments so that both results agree. Calibration methods can involve formal optimization methods or manual methods in which the modeler informally examines alternative model parameters. The development of a calibration framework typically involves the following: (1) definition of the model variables, coefficients, and equations; (2) selection of an objective function to measure the quality of the calibration; (3) selection of the set of data to be used for the calibration process; and (4) selection of an optimization/manual scheme for altering the coefficient values in the direction of reducing the objective function. Hydraulic calibration usually involves the modification of system demands, fine-tuning the roughness values of pipes, altering pump operation characteristics, and adjusting other model attributes that affect simulation results, in particular those that have significant uncertainty associated with their values. From the previous steps, it is clear that model calibration is neither unique nor a straightforward technical task. The success of a calibration process depends on the modeler's experience and intuition, as well as on the mathematical model and procedures adopted for the calibration process. This paper provides a summary of the Battle of the Water Calibration Networks (BWCN), the goal of which was to objectively compare the solutions of different approaches to the calibration of water distribution systems through application to a real water distribution system. Fourteen teams from academia, water utilities, and private consultants participated. The BWCN outcomes were presented and assessed at the 12th Water Distribution Systems Analysis conference in Tucson, Arizona, in September 2010. This manuscript summarizes the BWCN exercise and suggests future research directions for the calibration of water distribution systems.


This paper summarizes the results of the Battle of Water Calibration Networks competition that was held in Tucson Arizona in 2010. The competition was based on using a single system that turned out to be fairly complicated and perhaps diminished the ability to derive any general rules of thumb from the competition. Different participants made different assumptions that could impact the associated solutions. If nothing else, the paper tends to underscore the complex nature of model calibration.


Ostfeld, A., Salomons, E., Ormsbee, L., et. al., (2012) The Battle of the Water Calibration Networks, ASCE Journal of Water Resources Planning and Management Vol 138, (5).

Page 2 of 2




Year Month Day

2012 September

Field No. 3 Author



Secondary --- ---

Tertiary --- ---

Additional --- ---


Calibration Workshop


Book Reference

Conference Paper

Journal Paper

Technical Report



X X X


Name WDSA Conference

Location Adelaide SA Australia



Page 1 of 2


Field Data Data Quality


These are notes from a two hour session that presented the basics of model calibration and gave the attendees an opportunity to think through how they would solve problems in model calibration.


The paper discussed the need for calibration, the kinds of data required, identification of the parameter to be adjusted, and a discussion of when the calibration can be considered complete.


Page 2 of 2




Year Month Day

2012 September - October

Field No. 3 Author


Primary Wu Zheng

Secondary Walski Thomas

Tertiary --- ---

Additional --- ---


An Effective Approach for Solving Battle of Water Calibration Network Problem


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Journal of Water Resources Planning & Management

Location



138 5 533 - 542

Page 1 of 2


Optimization Pressure Measurement


This paper presents a solution method and the results for Battle Water Calibration Network (BWCN) problem. It is solved in a progressive manner of optimizing model parameters with sound engineering judgment. The model calibration has been completed by undertaking multiple steps, including (1) constructing the initial Extended Period Simulation (EPS) model with the given model and SCADA data; (2) calibrating for static and fire flow test data; and (3) calibrating EPS model for given SCADA data over 167 hours. The calibration tasks were iteratively conducted per District Meter Area (DMA), verified and then fine tuned for the whole system. While the field data contained some noise, good model calibration has been achieved for BWCN.


The paper showed that a model cannot be calibrated in one quick step but instead, resolving the issues was more like peeling an onion and involved a good deal of engineering judgment.


Page 2 of 2




Year Month Day

2012 September

Field No. 3 Author


Primary Wu Zheng

Secondary Song Yuan

Tertiary

Additional


Optimizing Pressure Logger Placement for Leakage Detection and Model Calibration


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Proceedings from 14th Water Distribution Systems Analysis Conference

Location Adelaide SA Australia



858 - 867

Page 1 of 2


Hydraulic model Calibration Pressure logger Monte Carlo Tracer


Pressure loggers are used to record field pressure data, which are the essential information for water utilities to achieve sound model calibration. Thus determining where and how many pressure loggers to be placed in a distribution system is an important task. In this paper, an effective method is presented for optimizing pressure logger placement. It is developed into a two-stage solution method. At the first stage, a Mont Carlo method is used to generate a large number of random events, each of them represents either demand change and/or leakage flow. All the events are simulated by conducting hydraulic model analysis. The simulated nodal pressures are compared with the baseline condition. The pressure change at each node is evaluated with respect of logger accuracy. If the pressure change is greater than the logger accuracy, a value of 1 is assigned to the node for an event, otherwise a 0 is a assigned to the node. Thus a binary database is constructed for the randomized event for a given distribution system. The constructed binary database is employed to optimize the pressure logger locations in the second stage. The pressure logger locations are optimized for a given number of loggers such that the randomized events are detected or covered as many as possible. The method is tested on two systems. The results are compared with the pressure logger locations previously designed by the experienced engineers. It shows the method is able to achieve greater coverage with less number of pressure loggers than the sampling design by experienced engineers.


This paper shows the use of genetic algorithms to optimize the number and placement of pressure loggers for network calibration. It would be interesting to see the difference in calibration in terms of time and budget to calibrate the model between the two methods (optimized placement vs sampling design by experienced engineers). The approach may make sense if there is a restriction with the number of loggers that a utility can use. Otherwise, it seems that the more pressure loggers (ie more data points) would assist in calibrating a model (validating c-factors, perhaps identifying closed valves, etc.)


ISBN 978-1-922197-58-9

Page 2 of 2




Year Month Day

2012

Field No. 3 Author


Primary Clark Robert M.

Secondary

Tertiary

Additional


Modeling Water Quality in Distribution Systems, Second Edition


Book Reference

Conference Paper

Journal Paper

Technical Report



X






Appendix A 275 - 310

Page 1 of 2


Calibration Validation Tracer Study Water Quality Chlorine Decay

Fluoride Dosage


Appendix A in this publication covers tracer studies as a method of calibration/validation of a water quality model. Fluoride, calcium chloride, sodium chloride and others are reviewed as potential tracers. Field equipment selection and procedures are also reviewed including injection pumps, tracer storage and dosage rate measurement, and distribution system flow rate measurement. A discussion of field measurements of tracer concentrations as well as developing a detailed study design and executing a tracer study are also presented. Tracer study costs are also summarized. Dynamic calibration methods for developing a water quality model are summarized. Two case studies are presented both using calcium chloride tracer studies, one for a small-suburban dead-end system and one for a large suburban pressure zone.



Page 2 of 2




Year Month Day

2012 September

Field No. 3 Author


Primary Masoud Asadzadeh

Secondary Tolson Bryan

Tertiary

Additional


Assessing the impact of alternative pipe groupings on multi-objective water distribution network calibration


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Barton, A.C.T.: Engineers Australia

Location Adelaide South Australia



NA NA 19 - 27

Page 1 of 2



Simulation Calibration Pipe grouping Hydraulic simulator Multi-objective


Pipe roughness coefficient calibration is a common practice when an existing water distribution network (WDN) with the known layout and pipe diameters is being modelled. Model calibration aims to reduce the model error (difference between observed and simulated data) by adjusting the model parameter values. Two alternative pipe groupings of a WDN calibration problem are studied to measure the impact of reducing the number of decision variables on the model error. Model error is calculated for fire flow test and SCADA measurements separately and the calibration is solved as a bi-objective optimization problem. Results show that, although reducing the number of decision variables (grouping more pipes together) makes the problem easier to be calibrated, it can significantly reduce the quality of the calibrated model. Therefore, instead of reducing the number of decision variables only due to the lack of large computational budget, it is recommended to use an efficient optimization algorithm.


Part of the Battle of the Water Calibration competition (BWCN).


Asadzadeh, Masoud and Tolson, Bryan. Assessing the impact of alternative pipe groupings on multi-objective water distribution network calibration [online]. In: WDSA 2012: 14th Water Distribution Systems Analysis Conference, 24-27 September 2012 in Adelaide, South Australia. Barton, A.C.T.: Engineers Australia, 2012: 19-27. Availability: <http://search.informit.com.au/documentSummary;dn=944140895392343;res=IELENG> ISBN: 9781922107589. [Cited 17 Oct 14].

Page 2 of 2




Year Month Day

2012 September

Field No. 3 Author


Primary Syed Juned

Secondary Wu Zheng Yi

Tertiary Al Nuaimi Hind Saif

Additional


SUFFICIENCY OF DATA LOGGERS FOR OPTIMIZED MODEL CALIBRATION OF WATER DISTRIBUTION NETWORKS


Book Reference

Conference Paper

Journal Paper

Technical Report



X


Name Australian Society of Civil Engineers

Location Adelaide Austrialia



Page 1 of 2



The degree of accuracy of any hydraulic model’s output is primarily dependent upon the extent of calibration conducted with the observed flow and pressure data, which are mostly recorded by using data loggers at different locations of the modelled area. In General, the more loggers are placed and used for data collection, the better the model can be calibrated, but the greater the cost is for the modelling project. In this study, the optimized calibration has been performed to investigate the sufficiency of the field data with respect to the numbers and locations of data loggers. The comparative analysis has been made based on the root mean square error (RMSE) of flows and hydraulic grades, and also the number of detected leakage nodes that are compared with the leakage locations found in the field. It is indicated that a good trade-off must be achieved between the number of data loggers and sound solution in terms of detected leakage nodes and RMSE. The outcomes of this study would help engineers to minimize CAPEX (Capital Expenditures) and OPEX (Operating Expenditures) required for the placement and maintenance of data loggers in a municipal water network.



Page 2 of 2




Year Month Day

2013

Field No. 3 Author


Primary Panguluri Srinivas

Secondary Krishnan Radha

Tertiary Garner Lucille

Additional

Patterson Lee

Hartman Grayman

Clark Piao

Craig Yeongho

David Walter Robert

Haishan


Using Continuous monitors for Conducting Tracer Studies in Water Distribution Systems


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Tracer test EPANET Skeletonized model All-pipe model Continuous monitoring


The use of online monitors for conducting a distribution system tracer study is proving to be a helpful tool to accurately understand the flow dynamics in a distribution system. In a series of field tests sponsored by the U. S. Environmental Protection Agency (EPA) and the Greater Cincinnati Water Works (GCWW) in 2002-2003, a food-grade calcium chloride tracer was introduced into a water system network and the movement of the chemical was traced using strategically placed automated online conductivity meters (in conjunction with a limited grab sampling program). The benefits and results of this field testing effort were discussed in this paper.

The study results illustrated that continuous monitoring data played a key role in the successful calibration of the model. EPANET modeling time step adjustments and quick reaction to the tracer concentration would not have been possible without the use of continuous monitors. The continuous monitoring of the flow allowed for the adjustment in water demand inputs which also played a key role in successful calibration and refinement of the model. The results also illustrated that, depending on the level of refinement (and calibration), there is a significant variation in the capability of the EPANET model to accurately represent the system. In general, the parts of the network that were configured as trees (main stem with branches) are more easily calibrated by making adjustments in demands. For looping parts of the system and at dead-ends, results are very sensitive to small variations in demands and system configuration, leading to the possibility of significant prediction errors at some locations.



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Year Month Day

2013

Field No. 3 Author


Primary Johnson Reese P.

Secondary Blackschleger Victoria

Tertiary Boccelli Dominic L.

Additional Lee Yeongho


Water Security Initiative Field Study: Improving Confidence in a Distribution System Model


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Name ?EPA?

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Water Quality Field Study Trace Test Tracer Monitoring

Equipment EPS


The US Environmental Protection Agency (EPA) instituted the Water Security Initiative to design, deploy, and evaluate a model contamination warning system (CWS) for drinking water utilities. Through a cooperative agreement with the Greater Cincinnati Water Works (GCWW), the first pilot system has been designed and implemented in Cincinnati, Ohio. Deployment of this CWS relied on in-depth understanding of the hydraulic and water quality parameters that exist in the GCWW’s distribution network. As a result, a tracer test field study was designed as part of the pilot to assess the accuracy of the utility’s distribution system model with particular emphasis placed on evaluating transport-related aspects. This field study is considered to be the largest tracer test of a distribution network completed in the United States. Its purpose was unique in that the study was designed to test how well the model would predict conditions in the actual distribution system, rather than being designed to calibrate the model. The field study provided an unparalleled opportunity to improve our understanding of the predictive ability of a network model for representing transport within a very large, complex network. Our experiences are shared to provide any utility interested in improving its knowledge of, and confidence in, its distribution system model valuable insights into the necessary procedures, equipment, effort, and costs.


With respect to model calibration, the paper provides a brief description a case study of EPS calibration and discusses the issues associated with it. It also includes model verification using a comprehensive tracer study.


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Year Month Day

2013 May 20 - 22

Field No. 3 Author


Primary Walton Reese

Secondary Yost Scott


Additional


“Organizing Water Distribution System Data in A Dynamic Web Database”


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This paper discusses a case study that uses a dynamic website combined with a smartphone application to collect and store water distribution system data for both operation, maintenance, and model calibration applications. The application construction involved digitizing over 4,000 paper records pertaining to network operations and infrastructure maintenance then programming a website that can retrieve, edit and append more information into the database. Smartphones were used because the utility using the new data collection system is smaller than average and the phones were readily available to most of the field technicians. This study also deals with internet security threats to sensitive water utility data.



Walton, R., Yost, S., Ormsbee, L., (2013) “Organizing Water Distribution System Data in A Dynamic Web Database,” 2013 World Environmental and Water Resources Congress, ASCE, Cincinnati, OH, 20-22 May 2013.

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Year Month Day

2013 May 20 - 22

Field No. 3 Author


Primary Goodin Joe

Secondary Yost Scott

Tertiary Bryson Sebastian

Additional Ormsbee Lindell


“Organizing/Planning/Executing a Grab Sampling Tracer Study for a Small to Medium Sized Water Utility”


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Tracer studies have been used throughout the years for a variety of different purposes. These types of studies can provide data that can be used to calculate travel time, residence time or age of water in a distribution network. Tracer studies can also be used to help verify and further calibrate existing hydraulic models. When conducting a tracer study, there are several different components that need to be addressed to ensure the results of the study are acceptable and useful. This paper discusses issues and provide guidance for future fluoride tracer studies, conducted using a grab sampling approach, for a small to medium sized utility. Topics addressed are: 1) Potential cost components of the study 2) How to properly select ideal sampling sites using a hydraulic model and issues that arise from potential flow reversals in the distribution system 3) Importance of tank sampling to help accurately reflect tank mixing 4) How to utilizing sampling when fluoride is turned down to predict/verify sampling locations when fluoride is turned back up. 5) Issues pertaining to reliability of field fluoride colorimeters 6) Organization and scheduling concerns 7) Overall lessons learned and modeling tips from a fluoride tracer study conducted for a medium sized utility.



Goodin, J., Yost, S., Bryson, S., Ormsbee, L., (2013) “Organizing/Planning/Executing a Grab Sampling Tracer Study for a Small to Medium Sized Water Utility: Lessons Learned, 2013 World Environmental and Water Resources Congress, ASCE, Cincinatti, OH, 20-22, May 2013.

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Year Month Day

2013 --- ---

Field No. 3 Author


Primary Jolly Matthew

Secondary Lothes Amanda

Tertiary Bryson Sebastian

Additional Ormsbee Lindell


“Research Database of Water Distribution System Models”


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Hydraulic Model Databases Network Analysis


Since the 1960's researchers have continued to develop new methodologies and algorithms in support of the planning, design, and management of water distribution systems. While initial research focused on modeling the hydraulics of such systems, the 1980's gave rise to additional research focus on water quality issues. More recent research has expanded into issues of system reliability and resilience, energy management, and sensor and chlorine booster station placement. In most cases, researchers have either relied on hypothetical water distribution systems or a handful of actual systems for use as benchmark test systems. Some of the more widely used actual systems include the New York tunnel system and the Hanoi water distribution system. This paper describes the development of a database of several water distribution systems that have been synthesized from a statewide database of systems originally developed by the Kentucky Infrastructure Authority. The developed models include both small and medium sized networks as well a range of system characteristics (i.e. system configuration — grid, looped and branched systems, and system components — number of tanks, pump stations, and supply sources). The development of the database is described as well as how to gain access to the developed models. All models have been developed to support use by either KYPIPE or EPANET.


The models described in this paper can be obtained free of charge from the University of Kentucky.


Jolly, M., Lothes, A., Bryson, S., Ormsbee, L., (2013) Research Database of Water Distribution System Models, ASCE Journal of Water Resources Planning and Management. 10.1061/(ASCE)WR.1943-5452.0000352.

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American Water Works Association Engineering Modeling