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Systems approach to water management
Ecological Modelling, 3 ( 1 9 7 7 ) 7 3 - - 7 6 © Elsevier Scientific P u b l i s h i n g C o m p a n y , A m s t e r d a m - - P r i n t e d in T h e N e t h e r l a n d s
73
Book Review
Systems Approach to Water Management. A.K. Biswas (Editor). McGraw-Hill Publishing Company, New York, N.Y., 1976, 450 pp., $ 23.00. This impressive b o o k is the result of assembling a distinguished group of contributors to prepare comprehensive chapters in their own fields of specialization directed at water resources problems within a prescribed framework. The emphasis is on the interdisciplinary approach to water resources management by systems analysis. The first chapter, by Asit K. Biswas, reviews some of the fundamental aspects of water resources management. It discusses the reasons which have contributed to making the water-resources management process exceedingly complex at present, and it points out that the process will b e c o m e increasingly more complex in the future. In spite of increasing complexities, the average planner or decision-maker has been provided with a few fundamentally new tools and concepts during the past several decades. One of these few new tools is systems analysis. The concept of systems analysis, with direct reference to water, is explained, and so also are the different categories of models. The concept of multi-objective planning, including the difficulties associated with such a process, is also discussed. The next nine chapters deal with models in specific areas. The second chapter examines rainfall-runoff models. One of the key hydrological problems has always been to estimate the flow of ungaged streams or to extend the available records of gaged streams. Ray K. Linsley succinctly describes the structure of a water-balance model, including the functions of rainfall, evaportranspiration, interception, impervious area runoff, soil moisture storage, infiltration, interflow, upper zone storage, overland flow, interflow discharge, ground water, and other relevant parameters. The chapter ends, appropriately enough, with some thoughts on the application as well as the future of simulation, which logically leads to the next chapter: generation of synthetic flow sequences. Nicholas C. Matalas and J.R. Wallis point out that the design of a waterresource system is dependent, in part, upon the sequences of streamflow that are assumed to be realized over the system's economic life. Unfortunately, the generating mechanism of streamflow is unknown, b u t this mechanism can be approximated, and an ensemble of " f u t u r e " flow sequences, referred to as synthetic flow sequences, can be generated. Over the past decade, a series of techniques has been developed for generating synthetic flow sequences, most of which have been based on short-memory processes to approximate long-term persistence that is evident in many historical flow sequences. Matalas and Wallis review the developments thus far in this area. Chapter 4 is a comprehensive analysis of ground-water problems b y the late Chester C. Kisiel and Lucien Duckstein. It identifies the current state of
74 modelling, as well as its deficiencies. The focus is on emerging approaches to describing and managing the ground-water system and not on the many theoretical and empirical solutions to regional and specialized ground-water problems. Some e~amples of specific methodologies are given. Various groundwater mode~/have been summarized, along with some statements about their properties/~vl~ich should enable one to select a suitable methodology. A significa~(t p ~ t of this chapter is relevant to problems other than groundwater. Thes? are some of the important techniques and considerations, i.e., model choice, multilevel optimization, hybrid computations, adjustment algorithms,multiobjective features, and fundamental problems like uncertainties, error growth, worth of data, and economic losses. The subject changes from ground-water to surface-water management in the next two chapters. Daniel P. Loucks examines the status and application of models to the management of surface-water. Since the emphasis on surface-water in a real world is considerable (in fact it provides the major portion of the world's agricultural, industrial, and domestic water supplies), the Editor quite rightly has decided to treat the problem in t w o consecutive chapters: the first dealing with the quantity aspect of the problem and the second with the quality aspect. The first chapter is concerned with the definition and evaluation of alternatives for controlling the allocation and distribution of surface-water flows within a region. The chapter captures the essence of the procedures available to analyse surface-water management alternatives and at the same time provides additional information on the risks associated with various investment and operating policies. Specifically, the models discussed serve as a means of illustrating h o w preliminary estimates can be made of the desired a m o u n t and reliability of various yields or allocations of water to each consumptive or nonconsumptive use and the requirements, if any, for within or over the year, and flood-control storage cacacity in multipurpose reservoirs. Loucks correctly points out that developing models of river basin systems is an art. There is no single best way to do it, although for specific problems some approaches are better than others. The next chapter examines a variety of models for selection of water-quality management policies for surface-waters. It reviews recently proposed important models for defining and evaluating combinations of waste-water reduction and treatment, artificial aeration, flow augmentation, and bypass piping alternatives for the management of dissolved oxygen concentrations. It contains a comprehensive discussion on the prediction and control of water quality, including alternative methods available for water-quality control. It shows h o w the quality standards and objectives can be incorporated within a modelling framework. Several types of river quality control models are analysed, including waste-water treatment and reduction models, thermal-loading control models, flow augmentation models, artificial aeration models, and waste-water transport models. Mathematical modelling of estuarial systems is next discussed b y Gerald T.
75 Orlob. The estuary is one of the most complex and challenging systems that any water-resource analyst has to deal with. Up until recent years, it was extremely difficult to analyse the complexities of the system's behaviour. Physical models have been used with some success, but these were n o t very successful in dealing with the dimension of quality. Developments in computer technology have made it possible to determine analytical solutions to this formidable class of problems -- so much so that mathematical models have become the most useful tools for estuarial water management. Some of the major estuarial models developed so far are reviewed and analysed. There are also sections on model calibrations and their potential applications. Donald J. O'Connor et al. consider ecologic models in Chapter 8. Ecologic models, in this context, are considered to be an analytical structure of broad segments of the aquatic ecosystem. Ecologic models have been constructed along several lines. For example, a large number of ecologic models have been developed with linear interactions. Some models, like p h y t o p l a n k t o n biomass models, have tended to be nonlinear because detailed nutrient interactions can be closely approximated. The main focus of the chapter is on a linear model of nitrification to analyse dissolved oxygen in natural water bodies. The models discussed progress from relatively simple nitrogen equivalent BOD models to more complex ones having feedback effects. Chapter 9, by Charles W. Howe, is on economic modelling, which is intended to relate uses of other scarce resources, and to provide criteria for ranking different water development and management policies. It is necessary to model the physical system which influences those dimensions of welfare measured by income, its distribution among subsets of the population, the generation of e m p l o y m e n t , and physical environmental conditions. The first half of the chapter provides a concise discussion of contemporary issues in the social evaluation of water. The second half reviews the recent economic modelling achievements in the water-resources area. The achievements are divided into seven classes, representing important model types and/or problem areas in which important advances have been made. The seven classes of models are then discussed. Finally, areas which warrant substantial additional research investigations are pointed out. Specific models by different areas are discussed in the preceding chapters. Chapter 10, by Douglas A. Haith and Daniel P. Loucks, looks at multiobjective water-resources planning, some fundamental aspects of which are reviewed in the first chapter. In order to deal with the complexities of multiobjective planning, planners usually construct simplified representations or models of their problems that can range from solely conceptual ones to those that have to be solved by high-speed digital computers. General experience indicates that some alternatives are preferable when certain objectives are considered but that those alternatives change when different objectives are examined. As the number of objectives and alternatives being considered increases, the ability of the planners to manage the problem decreases. This
76
is where modelling can play a tremendously important part as an aid to making decisions. Some of the major topics analysed are quantification of planning objectives, models for multiobjective planning -- including the problems of trade-off and political feasibility, formulation of planning alternatives and plan selection. It is suggested that what is needed is a methodology that does not require explicit intervention b y the political decision-makers b u t makes use of a value judgment that has to be defined by the political decision-making process. The role of mathematical modelling in water-resources decision-making and its present status are explored in depth by Asit K. Biswas in the final chapter. The primary role of a decision-maker is to make right decisions on the basis of available information and within the allowable time and resource constraints. The basic types of models used for decision-making, technocratic and incremental, are discussed, and so are the c o m m o n criteria of the decision-making process in a real world. Even though modelling can add an important dimension to the decision-making process, surprisingly enough it still lacks credibility with the policy makers. The reasons for this "credibility gap" are analysed, and what is more important is the fact that Biswas offers, for the first time anywhere the reviewer has seen, concrete and meaningful suggestions as how to make models more relevant. Water resources management is a complex field, and it is difficult, if not impossible, for any single person to write a comprehensive b o o k that does justice to all its important components. Biswas, by carefully developing an over-all framework, and by persuading some of the world's leading authorities to contribute well-written and co-ordinated chapters, has produced a most impressive text that is b o u n d to be considered the "Bible" by everyone concerned with water management for many years to come. PETER J. REYNOLDS
(Ottawa, Ont., Canada)
73
Book Review
Systems Approach to Water Management. A.K. Biswas (Editor). McGraw-Hill Publishing Company, New York, N.Y., 1976, 450 pp., $ 23.00. This impressive b o o k is the result of assembling a distinguished group of contributors to prepare comprehensive chapters in their own fields of specialization directed at water resources problems within a prescribed framework. The emphasis is on the interdisciplinary approach to water resources management by systems analysis. The first chapter, by Asit K. Biswas, reviews some of the fundamental aspects of water resources management. It discusses the reasons which have contributed to making the water-resources management process exceedingly complex at present, and it points out that the process will b e c o m e increasingly more complex in the future. In spite of increasing complexities, the average planner or decision-maker has been provided with a few fundamentally new tools and concepts during the past several decades. One of these few new tools is systems analysis. The concept of systems analysis, with direct reference to water, is explained, and so also are the different categories of models. The concept of multi-objective planning, including the difficulties associated with such a process, is also discussed. The next nine chapters deal with models in specific areas. The second chapter examines rainfall-runoff models. One of the key hydrological problems has always been to estimate the flow of ungaged streams or to extend the available records of gaged streams. Ray K. Linsley succinctly describes the structure of a water-balance model, including the functions of rainfall, evaportranspiration, interception, impervious area runoff, soil moisture storage, infiltration, interflow, upper zone storage, overland flow, interflow discharge, ground water, and other relevant parameters. The chapter ends, appropriately enough, with some thoughts on the application as well as the future of simulation, which logically leads to the next chapter: generation of synthetic flow sequences. Nicholas C. Matalas and J.R. Wallis point out that the design of a waterresource system is dependent, in part, upon the sequences of streamflow that are assumed to be realized over the system's economic life. Unfortunately, the generating mechanism of streamflow is unknown, b u t this mechanism can be approximated, and an ensemble of " f u t u r e " flow sequences, referred to as synthetic flow sequences, can be generated. Over the past decade, a series of techniques has been developed for generating synthetic flow sequences, most of which have been based on short-memory processes to approximate long-term persistence that is evident in many historical flow sequences. Matalas and Wallis review the developments thus far in this area. Chapter 4 is a comprehensive analysis of ground-water problems b y the late Chester C. Kisiel and Lucien Duckstein. It identifies the current state of
74 modelling, as well as its deficiencies. The focus is on emerging approaches to describing and managing the ground-water system and not on the many theoretical and empirical solutions to regional and specialized ground-water problems. Some e~amples of specific methodologies are given. Various groundwater mode~/have been summarized, along with some statements about their properties/~vl~ich should enable one to select a suitable methodology. A significa~(t p ~ t of this chapter is relevant to problems other than groundwater. Thes? are some of the important techniques and considerations, i.e., model choice, multilevel optimization, hybrid computations, adjustment algorithms,multiobjective features, and fundamental problems like uncertainties, error growth, worth of data, and economic losses. The subject changes from ground-water to surface-water management in the next two chapters. Daniel P. Loucks examines the status and application of models to the management of surface-water. Since the emphasis on surface-water in a real world is considerable (in fact it provides the major portion of the world's agricultural, industrial, and domestic water supplies), the Editor quite rightly has decided to treat the problem in t w o consecutive chapters: the first dealing with the quantity aspect of the problem and the second with the quality aspect. The first chapter is concerned with the definition and evaluation of alternatives for controlling the allocation and distribution of surface-water flows within a region. The chapter captures the essence of the procedures available to analyse surface-water management alternatives and at the same time provides additional information on the risks associated with various investment and operating policies. Specifically, the models discussed serve as a means of illustrating h o w preliminary estimates can be made of the desired a m o u n t and reliability of various yields or allocations of water to each consumptive or nonconsumptive use and the requirements, if any, for within or over the year, and flood-control storage cacacity in multipurpose reservoirs. Loucks correctly points out that developing models of river basin systems is an art. There is no single best way to do it, although for specific problems some approaches are better than others. The next chapter examines a variety of models for selection of water-quality management policies for surface-waters. It reviews recently proposed important models for defining and evaluating combinations of waste-water reduction and treatment, artificial aeration, flow augmentation, and bypass piping alternatives for the management of dissolved oxygen concentrations. It contains a comprehensive discussion on the prediction and control of water quality, including alternative methods available for water-quality control. It shows h o w the quality standards and objectives can be incorporated within a modelling framework. Several types of river quality control models are analysed, including waste-water treatment and reduction models, thermal-loading control models, flow augmentation models, artificial aeration models, and waste-water transport models. Mathematical modelling of estuarial systems is next discussed b y Gerald T.
75 Orlob. The estuary is one of the most complex and challenging systems that any water-resource analyst has to deal with. Up until recent years, it was extremely difficult to analyse the complexities of the system's behaviour. Physical models have been used with some success, but these were n o t very successful in dealing with the dimension of quality. Developments in computer technology have made it possible to determine analytical solutions to this formidable class of problems -- so much so that mathematical models have become the most useful tools for estuarial water management. Some of the major estuarial models developed so far are reviewed and analysed. There are also sections on model calibrations and their potential applications. Donald J. O'Connor et al. consider ecologic models in Chapter 8. Ecologic models, in this context, are considered to be an analytical structure of broad segments of the aquatic ecosystem. Ecologic models have been constructed along several lines. For example, a large number of ecologic models have been developed with linear interactions. Some models, like p h y t o p l a n k t o n biomass models, have tended to be nonlinear because detailed nutrient interactions can be closely approximated. The main focus of the chapter is on a linear model of nitrification to analyse dissolved oxygen in natural water bodies. The models discussed progress from relatively simple nitrogen equivalent BOD models to more complex ones having feedback effects. Chapter 9, by Charles W. Howe, is on economic modelling, which is intended to relate uses of other scarce resources, and to provide criteria for ranking different water development and management policies. It is necessary to model the physical system which influences those dimensions of welfare measured by income, its distribution among subsets of the population, the generation of e m p l o y m e n t , and physical environmental conditions. The first half of the chapter provides a concise discussion of contemporary issues in the social evaluation of water. The second half reviews the recent economic modelling achievements in the water-resources area. The achievements are divided into seven classes, representing important model types and/or problem areas in which important advances have been made. The seven classes of models are then discussed. Finally, areas which warrant substantial additional research investigations are pointed out. Specific models by different areas are discussed in the preceding chapters. Chapter 10, by Douglas A. Haith and Daniel P. Loucks, looks at multiobjective water-resources planning, some fundamental aspects of which are reviewed in the first chapter. In order to deal with the complexities of multiobjective planning, planners usually construct simplified representations or models of their problems that can range from solely conceptual ones to those that have to be solved by high-speed digital computers. General experience indicates that some alternatives are preferable when certain objectives are considered but that those alternatives change when different objectives are examined. As the number of objectives and alternatives being considered increases, the ability of the planners to manage the problem decreases. This
76
is where modelling can play a tremendously important part as an aid to making decisions. Some of the major topics analysed are quantification of planning objectives, models for multiobjective planning -- including the problems of trade-off and political feasibility, formulation of planning alternatives and plan selection. It is suggested that what is needed is a methodology that does not require explicit intervention b y the political decision-makers b u t makes use of a value judgment that has to be defined by the political decision-making process. The role of mathematical modelling in water-resources decision-making and its present status are explored in depth by Asit K. Biswas in the final chapter. The primary role of a decision-maker is to make right decisions on the basis of available information and within the allowable time and resource constraints. The basic types of models used for decision-making, technocratic and incremental, are discussed, and so are the c o m m o n criteria of the decision-making process in a real world. Even though modelling can add an important dimension to the decision-making process, surprisingly enough it still lacks credibility with the policy makers. The reasons for this "credibility gap" are analysed, and what is more important is the fact that Biswas offers, for the first time anywhere the reviewer has seen, concrete and meaningful suggestions as how to make models more relevant. Water resources management is a complex field, and it is difficult, if not impossible, for any single person to write a comprehensive b o o k that does justice to all its important components. Biswas, by carefully developing an over-all framework, and by persuading some of the world's leading authorities to contribute well-written and co-ordinated chapters, has produced a most impressive text that is b o u n d to be considered the "Bible" by everyone concerned with water management for many years to come. PETER J. REYNOLDS
(Ottawa, Ont., Canada)