Hydrology Principles Analysis Design

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Copyright 2006 New Age International (P) Ltd., Publishers Published by New Age International (P) Ltd., Publishers All rights reserved. No part of this ebook may be reproduced in any form, by photostat, microfilm, xerography, or any other means, or incorporated into any information retrieval system, electronic or mechanical, without the written permission of the publisher. All inquiries should be emailed to rights@newagepublishers.com

ISBN (10) : 81-224-2332-9 ISBN (13) : 978-81-224-2332-7


NEW AGE INTERNATIONAL (P) LIMITED, PUBLISHERS 4835/24, Ansari Road, Daryaganj, New Delhi - 110002 Visit us at www.newagepublishers.com





In this new Edition, two more Chapters are included, i.e., Chapter 17:Instantaneous Unit Hydrograph (IUH) with Clark and Nash Models illustrated with Workedout Examples from field data. Chapter 18:Cloud Seeding, the technique and operation being profusely illustrated with actual case histories in India and Russia. Also, some more illustrative Field Examples are included under Infiltration, Storm Correlation, Gumbels and Regional Flood Frequency. All, with a good print, sketches being neatly redrawn. Comments are always welcome and will be incorporated in the succeeding editions. H.M. Raghunath


( vii )




Hydrology is a long continuing hydroscience and much work done in this field in the past, particularly in India, was of empirical nature related to development of empirical formulae, tables and curves for yield and flood of river basins applicable to the particular region in which they were evolved by investigators like Binnie, Barlow, Beale and Whiting, Strange, Ryves, Dicken, Inglis, Lacey, Kanwar Sain and Karpov, etc. In this book, there is a departure from empiricism and the emphasis is on the collection of data and analysis of the hydrological factors involved and promote hydrological design on sound principles and understanding of the science, for conservation and utilisation of water resources. Hydrological designs may be made by deterministic, probabilistic and stochastic approaches but what is more important is a matured judgement to understand and avoid what is termed as unusual meteorological combination. The book is written in a lucid style in the metric system of units and a large number of hydrological design problems are worked out at the end of each article to illustrate the principles of analysis and the design procedure. Problems for assignment are given at the end of each Chapter along with the objective type and intelligence questions. A list of references is included at the end for supplementary reading. The book is profusely illustrated with sketches and is not bulky. The text has been so brought to give confidence and competence for the reader to sit for a professional examination in the subject or enable him to take up independent field work as a hydrologist of a River basin or sub-basin. The text is divided into Fundamental and Advanced topics and Appendices to fit the semester-hours (duration) and the level at which the course is taught. Degree and Post-degree students, research scholars and professionals in the fields of Civil and Agricultural Engineering, Geology and Earth Sciences, find this book useful. Suggestions for improving the book are always welcome and will be incorporated in the next edition. H.M. Raghunath


CONTENTSPreface to the Second Edition Preface to the First Edition (v) (vii)

PART AFUNDAMENTAL HYDROLOGY1 Introduction1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Worlds Water Resources Water Resources of India Hydrological Study of Tapti Basin (Central India) Hydrology and Hydrologic Cycle Forms of Precipitation Scope of Hydrology Hydrological Data Hydrologic Equation

13 3 5 11 13 14 14 15


Precipitation2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.11 2.12 2.13 2.14 Types of Precipitation Measurement of Precipitation Radars Rain-gauge Density Estimates of Missing Data and Adjustment of Records Mean Areal Depth of Precipitation (Pave) Optimum Rain-gauge Network Design Depth-Area-Duration (DAD) Curves Graphical Representation of Rainfall Analysis of Rainfall Data Mean and Median Moving Averages Curve Design Storm and PMP Snow Pack and Snow Melt

1717 18 22 22 23 26 31 33 36 38 43 48 49 49


Water Losses3.1 3.2 Water Losses Evaporation

6060 60

x 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 Evaporation Pans Soil Evaporation Unsaturated Flow Transpiration Evapotranspiration Hydrometeorology Infiltration Infiltration Indices Supra Rain Technique Watershed Leakage Water Balance


62 66 66 67 67 70 70 81 83 87 87


Runoff4.1 4.2 4.3 4.4 4.5 4.6 4.7 Components of Stream Flow Catchment Characteristics Mean and Median Elevation Classification of Streams Isochrones Factors Affecting Runoff Estimation of Runoff

9696 97 101 103 104 104 106


Hydrographs5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 5.10 5.11 Hydrograph Components Separation of Streamflow Components Hydrograph Separation Unit Hydrograph Unit Hydrograph from Complex Storms S-Curve Method Bernards Distribution Graph Instantaneous Unit Hydrograph Synthetic Unit Hydrographs Transposing Unit Hydrographs Application of Unit Hydrograph

117117 120 122 124 130 138 142 149 149 154 157


Stream Gauging6.1 6.2 6.3 6.4 Methods of Measuring Stream Flow Current Meter Gaugings Stage-Discharge-Rating Curve Selection of Site for a Stream Gauging Station

171171 174 178 183


Ground Water7.1 7.2 7.3 Types of Aquifers and Formations Confined and Unconfined Aquifers Darcys Law

192192 193 195


xi Transmissibility Well Hydraulics Specific Capacity Cavity Wells Hydraulics of Open Wells Construction of Open Wells Spacing of Wells 196 196 199 200 202 206 207

7.4 7.5 7.6 7.7 7.8 7.9 7.10


Floods-Estimation and Control8.1 8.2 8.4 8.5 8.6 8.7 8.8 8.9 Size of Floods Estimation of Peak Flood Flood Frequency Studies Encounter Probability Methods of Flood Control Soil Conservation Measures Flood Control Economics Flood Forecasting and Warning

212212 213 221 225 238 245 247 251


Flood Routing9.1 9.2 Reservoir Routing Stream Flow Routing

262262 270

10 Storage, Pondage and Flow Duration Curves10.1 10.2 10.3 Reservoir Mass Curve and Storage Flow Duration Curves Pondage

280280 285 288

11 Reservoir Sedimentation11.1 11.2 11.3 Sediment Movement and Deposition Reduction in Reservoir Capacity Reservoir Sedimentation Control

298298 300 303

12 Arid, Semi-Arid and Humid Regions12.1 12.2 12.3 Arid Regions Semi-Arid Regions Humid Regions

306306 307 309

PART BADVANCED TOPICS13 Linear Regression13.1 13.2 13.3 13.4 Fitting Regression Equation Standard Error of Estimate Linear Multiple Regression Coaxial Graphical Correlation of Rainfall Runoff

315315 316 319 322



14 Statistical and Probability Analysis of Hydrological Data14.1 14.2 Elements of Statistics Probability of Hydrologic Events

327327 332

15 Flood FrequencyProbability and Stochastic Methods15.1 15.2 15.3 15.4 15.5 Flood Frequency Methods Stochastic Method Stochastic Modelling by the Partial Duration Series Annual Flood PeaksRiver Ganga Regional Flood-Frequency Analysis (RFFA)

337337 344 344 358 361

16 Mathematical Models in Hydrology16.1 16.2 16.3 16.4 16.5 16.6 16.7 16.8 16.8 Type of Mathematical Models Methods of Determining IUH Synthetic Stream Flow Flow at Ungauged Sites by Multiple Regression Reservoir Mass Curve Residual Mass Curve Selection of Reservoir Capacity Flood Forecasting Mathematical Model

366366 371 379 381 381 383 383 386 389

17 Instantaneous Unit Hydrograph (IUH)17.1 17.2 17.3 17.4 17.5 17.6 17.7 IUH for a Basin Derivation of IUH Other Methods of Derivation of IUH NASH Conceptual Model Clarks Model Drawing Isochrones and Time-Area Diagram (TAD) Clarks Method

393393 393 394 394 397 398 398

18 Cloud Seeding18.1 18.2 18.3 18.4 Conditions for Cloud Seeding Cloud Seeding Technique Cloud Seeding Operation Recent Case History

403403 404 406 406

Appendices Selected References Bibliography Index

407 453 456 457






Hydrology is a branch of Earth Science. The importance of hydrology in the assessment, development, utilisation and management of the water resources, of any region is being increasingly realised at all levels. It was in view of this that the United Nations proclaimed the period of 1965-1974 as the International Hydrological Decade during which, intensive efforts in hydrologic education research, development of analytical techniques and collection of hydrological information on a global basis, were promoted in Universities, Research Institutions, and Government Organisations.



The Worlds total water resources are estimated at 1.36 108 ha-m. Of these global water resources, about 97.2% is salt water mainly in oceans, and only 2.8% is available as fresh water at any time on the planet earth. Out of this 2.8% of fresh water, about 2.2% is available as surface water and 0.6% as ground water. Even out of this 2.2% of surface water, 2.15% is fresh water in glaciers and icecaps and only of the order of 0.01% is available in lakes and streams, the remaining 0.04% being in other forms. Out of 0.6% of stored ground water, only about 0.25% can be economically extracted with the present drilling technology (the r