WEAP Demand Management

A Simple System

An Infrastructure Constraint

A Regulatory Constraint

Different Priorities

Different Priorities

For example, the demands of large farmers (70 units) might be Priority 1 in one scenario while the demands of smallholders (40 units) may be Priority 1 in another.

We will touch upon this further in the “Refining Supply” tutorial module

Different Preferences

Different Preferences

For example, a center pivot operator may prefer to take water from a tributary because of lower pumping costs.

Example

How much water will the site with 70 units of demand receive?

Example

How much water will be flowing in the reach between the Priority 2 diversion and the Priority 1 Return Flow?

Example

What could we do in order to insure that this reach does not go dry?

WEAP Hydrology Module-2 Bucket Method

Example

What could we do in order to insure that this reach does not go dry?

What are we assuming?

What are we assuming?

1. That we know how much water is flowing at the top of each river.

What are we assuming?

1. That we know how much water is flowing at the top of each river.

2. That no water is naturally flowing into or out of the river as it moves downstream.

What are we assuming?

1. That we know how much water is flowing at the top of each river.

2. That no water is naturally flowing into or out of the river as it moves downstream.

3. That we know what the water demands are with certainty.

What are we assuming?

1. That we know how much water is flowing at the top of each river.

2. That no water is naturally flowing into or out of the river as it moves downstream.

3. That we know what the water demands are with certainty.

4. Basicly, that this system has been removed from it HYDROLOGIC context.

What do we do now?

ADD HYDROLOGY!

Types of Models Hydrology, Rainfall/Runoff Models Hydraulic, Biophysical Process Models Planning, Water Resource Systems

Models

A Context for the WEAP approach…

Hydrology Model

Hydrology Model

Critical questions: How does rainfall on a catchment translate into flow in a river?

Hydrology Model

Critical questions: What pathways does water follow as it moves through a catchment?

Hydrology Model

Critical questions: How does movement along these pathways impact the magnitude, timing, duration and frequency of river flows?

Hydraulic Model

Hydraulic Model

Critical questions: How will the velocity, depth and horizontal extent of water flowing in a river channel, and the associated services provided by the river, change if flows are adjusted or the channel is modified?

Hydraulic Model

Critical questions: How fast, how deep and what is the horizontal extent of water flowing in a particular section of river?

Hydraulic Model

Critical questions: What is the interaction between the velocity, depth and horizontal extent of water flowing in a river and important services provided by the river (e.g. fish habitat, sediment transport, etc.)?

Planning Model

Planning Model

Critical questions: How should water be allocated to various uses in time of shortage?

Planning Model

Critical questions: How should infrastructure in the system (e.g. dams, diversion works, etc) be operated to achieve maximum benefit?

Planning Model

Critical questions: How can these operations be constrained to protect the services provided by the river?

Planning Model

Critical questions: How will allocation, operations and operating constraints change if new management strategies are introduced into the system?

The WEAP Hydrology Molude provides a

framework for answering these sets of questions.

The WEAP 2-Bucket Hydrology Module (Handout)

Smax

Rd z1(%) Interflow =

f(z1,ks, 1-f) Percolation = f(z1,ks,f)

Baseflow = f(z2,drainage_rate )

Et= f(z1,kc, ?, PET)

Pe = f(P, Snow Accum, Melt rate)

Plant Canopy

P

z2(%)

L

u

Surface Runoff =f(Pe,z1,1/LAI)

Irrigation

Rootzone Water Capacity (mm)

Deep Water Capacity (mm)

One 2-Bucket Model Per Land Class

WEAP Hydrology

Some Comments The number of parameters in the model are

fairly limited and are at least related to biophysical characteristics of the catchment.

The irrigation routine includes an implicit notion of irrigation efficiency.

Seepage can only pass from the lower bucket to the river, not the other way

hd

lw Sy,Ks

Percolation

Pumping

Groundwater representation

Some Comments The geometry of the aquifers in question are

representative, not absolute.

Stream stage fluctuations are assumed to represent average conditions.

While the ‘water table’ can fluctuate, it ignores all local fluctuations.

Time series wizard

Hydrology Data Input: Building Expressions

Expression Builder-Similar to EXCEL

Hydrology Data Input: Water-Year Method

•Describe a series of water year types from very dry to very wet

•Enter the water year sequence

Hydrology Data Input: Read from File

•Historical or synthetic data

•Import from ASCII files

Conclusions Hydrology The hydrology module is a powerful tool for considering

changing catchment dynamics.

Hydrology is essential for conducting rigorous analysis of climate change impacts.

Hydrology could be very interesting for livelihoods analysis because it considers several resources in a catchment, rainfed and irrigated agriculture, forest and range management, fish appropriate flows.

The critical question is whether it is as simple as possible, and no simpler.

Hydrology Tutorial Updates (Pg. 175)

Replaces Figure on Pg. 175 of tutorial

Hydrology Tutorial Additional Figure

Flow to River Full Irrigation, Exhibiting rather constant soil moisture in first bucket throughout the year (at 45-50%)

Hydrology Tutorial Updates (Pg. 180)

Replaces Figured on Pg. 180 of tutorial

Hydrology Tutorial Updates (Pg. 181)

Replaces Figured on Pg. 181 of tutorial