HYDROLOGICAL DIMENSIONING AND OPERATION OF RESERVOIRS

Transcription

1 HYDROLOGICAL DIMENSIONING AND OPERATION OF RESERVOIRS

2 Water Science and Technology Library VOLUME 39 Editor-in-Chief V. P. Singh, Louisiana State University, Baton Rouge, U.S.A. Editorial Advisory Board M. Anderson, Bristol, U.K. L. Bengtsson, Lund, Sweden J. F. Cruise, Huntsville, U.S.A. U. C. Kothyari, Roorkee, India S.E. Serrano, Lexington, U.S.A. D. Stephenson, Johannesburg, South Africa W.G. Strupczewski, Warsaw, Poland

3 HYDROLOGICAL DIMENSIONING AND OPERATION OF RESERVOIRS Practical Design Concepts and Principles by IMREY.NAGY Budapest Technical University & Committee for Water Resources Development, Hungarian Academy of Sciences, Hungary KOFI ASANTE-DUAH Anteon Corporation, Environment Division, San Diego, California, U.S.A. and ISTVAN ZSUFFA Department for Hydrology and Water Management, Budapest Technical University, Hungary Springer-Science+Business Media, B.V.

4 A C.I.P. Catalogue record for this book is available from the Library of Congress. ISBN ISBN (ebook) DOI / Cover illustration: Network flow representation of spatial and temporal configuration for multireservoir systems Printed on acid-free paper All Rights Reserved 2002 Springer Science+Business Media Dordrecht Originally published by Kluwer Academic Publishers in Softcover reprint of the hardcover 1st edition 2002 No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage and retrieval system, without written permission from the copyright owner.

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6 TABLE OF CONTENTS Preface xiii CHAPTER 1: INTRODUCTION Water Resources Management Planning and Design of Water Resources Systems Water Resources Systems Analysis Why Build Dams? The Need for Flow Regulation Systems Balancing Water Supply with Water Demands The Water Balance of Reservoirs as a Tool in Reservoir Design and Management Regional Imbalance Between Water Supply and Water Demand: Transboundary River Management Issues Impact of Reservoir Projects on the Temporal and Spatial Variation of Streamflow Quantity and Quality Environmental Impact Issues Associated with Dam and Reservoir Projects Using Storage Reservoirs in Flow Regulation and Water Management Schemes CHAPTER 2: THE HYDROLOGY OF FLOW REGULATION Flow Allocations Hydrological Problems Resulting from Water Deficiency Hydrological Problems Caused by Water Excess Types of Flow Regulation Daily Flow Regulation Weekly Flow Regulation Seasonal or Annual Flow Regulation Multiannual Flow Regulation Optimizing Flow Regulation Schemes General Characteristics of Flow Regulation Systems vii

7 viii CHAPTER 3: PLANNING FOR DAMS AND RESERVOIRS: HYDROLOGIC DESIGN ELEMENTS AND OPERATIONAL CHARACTERISTICS OF STORAGE RESERVOIRS The Reservoir Design Problem Reservoir-Site Selection The Case for Multipurpose Reservoirs Multireservoir System.Layout and Analyses Hydrological Basis for the Determination of Reservoir Storage Capacity A Model of Capacity Allocation and Survey of Water Demands in Multipurpose Reservoirs Estimating the Active Storage Necessary for Flow Regulation and Water Supply Hydroelectric Power Potential of Storage Reservoirs Storage-Space for Flood Mitigation: The Reservoir Flood Storage Capacity Design Siltation of Reservoirs and Sediment Reserve Storage Adjustment of Storage Estimates for Net Evaporation Losses Other Secondary Factors Affecting Reservoir Size-Selection Hydrologic Data Requirements and Analyses Selecting a Distribution for Use in the Hydrologic Design Process Bayesian Techniques for Parameter Estimation with Limited Data Design of Reservoir Storage for Stochastically Varying Water Demand Deterministic vs. Stochastic Methods in the Reservoir Design Problem Deterministic Methods and Models in Reservoir Design Stochastic Problems in the Design of Reservoirs Guidelines for the Hydrological Dimensioning of Reservoirs 59 CHAPTER 4: PRINCIPLES AND CONCEPTS IN THE HYDROLOGIC DESIGN AND OPERATION OF STORAGE RESERVOIRS Utilization of Reliability-Based Techniques in the Hydrologic Design Process The Concept of Reservoir Efficiency Functions The Efficiency Function as a Basis for Storage Determination General Types of Reliability Parameters vs. Reservoir Efficiency Functions Storage Allocation in Multipurpose Reservoirs Topographical Characteristic of the Reservoir Modeling Methodology for the Systems Simulation of Reservoir Design Problems A Flood Storage Submodel Optimal Release Policies in the Operation of Multipurpose Reservoirs Stochastic Approach to Establishing an Optimal Release Policy The Value of Hydrologic Information in the Management of Reservoirs 83

8 IX CHAPTER 5: SYSTEMS APPROACH IN THE HYDROLOGIC DESIGN AND OPERATION OF STORAGE RESERVOIRS Hydrologic Models in Water Resource Systems Time Series Models in Hydrologic Modeling Modeling Techniques Design of Reservoir Storage-Capacity with Inadequate Hydrologic Data The Need for Synthetic Data: Stochastic Generation of Synthetic Data and Flow Generation Strategies Multivariate Stochastic Models Evolution and Philosophy of Stochastic Simulation in Reservoir Systems Modeling and Design Deterministic-Stochastic Hybrid Models Risk and Uncertainty in Reservoir Design Model Verification and Perfonnance Reservoir Perfonnance Reliability Uncertainty Assessment via Sensitivity Analysis The Hydro-Economics of Reservoir Design Economic Concepts in Reservoir Planning Benefit-Cost and Cost-Effectiveness Analyses versus Optimal Design from Marginal Analysis Optimization Techniques as a Design Tool for Water Resource Systems The Optimization Problem Solution Techniques for the Optimization Problem Multiobjective Optimization in Reservoir Design The Net-Benefit Function Under Optimality Conditions Optimization Under Uncertainty and Risk CHAPTER 6: HYDROLOGIC ANALYSIS OF FLOOD FLOWS Design Flood Determination The Selection of an Acceptable Risk Level The Calculation of the Risk of Overtopping Hydro-Economic Impact Analysis Modeling the Flood Flows The Probability of Occurrence of Flood Flows Estimation of the Probability Distribution Function of the Maximum Flood Flows for Large Rivers Estimation of the Probability Distribution Function of the Maximum Flood Flows for Small Rivers Estimation of the Probability Distribution Function of Maximum Floods in the Case of Medium-sized Rivers Estimation of Flood Flows Using Limited Data Estimation of Flood Attenuation by Reservoirs III

9 x CHAPTER 7: METHODS OF APPROACH FOR DESIGNING OPTIMAL STORAGE CAPACITIES AND OPERATIONAL STRATEGIES FOR MUL TIRESERVOIR SYSTEMS A Review and Classification of Reservoir Capacity-Yield Estimation Procedures Critical Period Techniques Reservoir Capacity-Yield Estimation by Mass-curve Procedure Probability Matrix Methods Basic Principles of Reservoir Sizing Using Probabilistic Methods Reservoir Storage Requirements from Stochastic Data Basic Elements of Stocahstically-Generated Data Choosing Between Deterministic vs. Probabilistic vs. Simulation Methods CHAPTER 8: DETERMINATION OF THE OPTIMAL RESERVOIR STORAGE CAPACITY AND OPERATIONAL PARAMETERS FOR A RIVER DAM Screening Models for Multireservoir Systems Design A Cost-Efficient Reservoir Capacity Design in Multireservoir Systems Reservoir Network Analyses for Model Development Formulation of the Reservoir Model and Modeling Methodology Using Monte Carlo Techniques in the Optimal Design of Reservoir Systems A Multisite Multiseason Flow Generation Strategy The Multivariate Autoregressive AR(l) Model for the Multisite Annual Generation Scheme The Disaggregation of Annual Streamflow Data Implementation of the Flow Generation Algorithm Storage-Capacity Allocation to Reservoir Sites Determination of the Reservoir Sizing Factors Incorporating a Reliability Measure Matrix of, Dis aggregated' Water Demands Matrix of Storage Volumes Cost-Efficient Capacity Allocations in the Design of Multireservoir Systems An Optimal Solution for the Multireservoir System Design The Overall Model Implementation Process Optimal Storage Capacity Decisions for MuItireservoir Systems CHAPTER 9: HYDROLOGICAL SIZING OF RESERVOIRS FOR FLOOD PROTECTION 9.1. Determination of the Characteristic Hydrograph

10 xi l l Spillway and Sluice Gate Considerations in the Design and Operation of Flood Retention Reservoirs The Case for a Regulated Sluice The Case for a Closed Sluice The Case for an Opened Sluice Comparison of the Dimensioning Methods Approximate Evaluation of the Efficiency Function Emergency Flood Storage Impacts of Emergency Storage in the River System Design and Operation of an Emergency Flood Control Program CHAPTER 10: APPLICATION OF THE MORAN MODEL IN RESERVOIR STORAGE DESIGN O.2.l l The Moran Model A Proposed Mathematical Model Determination of the Transition Probabilities Model Application - An Example A Probabilistic Model for the Determination of the Reservoir Efficiency Function The Basic Hypotheses The Basic Relationships Determination of the Transition Probability Matrix Determination of the 'Behavior Function' Concluding Remarks LIST OF REFERENCES AND BIBLIOGRAPHY Literature Cited Additional Suggested Literature Index

11 PREFACE Storage reservoirs represent one of the most effective tools for eliminating, or at least for minimizing, discrepancies in the time and space variations of water resources distribution and requirements. In fact, the different - often contradictory - and increasing demands on water resources utilization and control usually can be fulfilled only by building multi-purpose reservoir systems. In this way, the available water resources can be exploited and/or managed in a more rational way. Typically, the construction of a dam across a river valley causes water to accumulate in a reservoir behind the dam; the volume of water accumulated in the reservoir will depend, in part, on the dimensions of the dam. The size of the dam will normally affect the capital expenditure in a very significant way. Indeed the construction of large water resource control systems - such as dams - generally involves rather huge manpower and material outlays. Consequently, the elaboration of effectual methods of approach that can be used in establishing the optimal reservoir parameters is of great practical significance. For instance, in the design and operation oflarge multi-reservoir systems, simple simulation and/or optimization models that can identify potentially costeffective and efficient system design are highly desirable. But it should be recognized that the problem of finding optimal capacities for multi-reservoir systems often becomes computationally complex because of the large number of feasible configurations that usually need to be analyzed. This book elaborates a systematic approach to the hydrological design and operation of reservoir storages that can be employed to help optimize the reservoir design process. It calls for the use of contemporary techniques and tools - especially for project planning; selection of reservoir site locations; water resources allocation and systems operation; best management practice decision-making; water quantity and quality assessments; hydrological monitoring studies; flood forecasting and flood control assessments; etc. Indeed, the application of novel techniques to hydrological problems are always very important - especially because problems often encountered in hydrological designs tend to require repeated sampling of the variables of interest, and that could become rather expensive. The novel methods of approach allows for the acquisition of information over large areas, and also for the better integration of all such data in a more cost-efficient manner. In addition, these methods of approach can allow a water resources system designer or analyst to engage in a variety of scenario evaluations that satisfy different project conditions - which can therefore facilitate an optimization of the overall system design and operation. By using the systematic approach offered by this title in a reservoir system design effort, different policies can be evaluated and compared, which will then facilitate the selection of an optimal design and operation plan for a proposed or existing dam project. xiii

12 xiv Overall, this book attempts to provide a concise, yet comprehensive overview of the hydrological dimensioning aspects relating to the design and operation of river dams. It elaborates some very important concepts, tools and methodologies that can be used to help resolve multiple reservoir capacity allocation problems in a consistent, efficient and cost-effective way. The material presented in the book will guide the hydrological analyst or design engineer in the determination of the optimal storage capacities and operational strategies of the individual elements in a system of reservoirs present at a set of potential dam sites. The specific goal in the type of optimization problem elaborated here will be to help minimize the reservoir capacities and/or shortfalls (which are a surrogate for minimizing costs) and still meet capacity requirements and needs. The ultimate objective in such an application will be to prevent over-design or under-design of reservoir storage capacities under optimum conditions of reservoir operation. Thus, the optimal solution will produce the smallest reservoir storages required to meet all project demands with an acceptable degree of reliability. The subject matter of this book should be of interest to practising hydrologists, water resources systems analysts and civil engineers, as well as to students taking a variety of courses in water resources planning and development. Weare indebted to a number of people for both the direct and indirect support afforded us during the period that we worked on this book project. Sincere thanks are due to our families, and several friends and colleagues who provided much-needed moral and enthusiastic support throughout preparation of the manuscript for this book. We thank the Publishing, Editorial and Production staff at Kluwer Academic Publishers (Dordrecht, The Netherlands) who helped bring this book project to a successful conclusion - with special thanks to Petra D. van Steenbergen (Publishing Editor); thanks also to several colleagues at Anteon Corporation, especially Max Voigtritter (Senior Program Manager) for providing miscellaneous support. We also wish to thank every author whose work is cited in this volume, for having provided some pioneering work to build on. Finally, it should be acknowledged that this book also benefited greatly from review comments of several anonymous individuals, as well as from discussions with a number of professional colleagues. Any shortcomings that remain are, however, the sole responsibility of the authors. Imre V. Nagy, Budapest, Hungary (August, 2001) Kofi Asante-Duah, San Diego, California, USA (August, 2001) Istvan Zsuffa, Budapest, Hungary (August, 2001)