wrm_fm.pdfwrm_ch01.pdfwrm_ch02.pdfwrm_ch03.pdfwrm_ch04.pdfwrm_ch05.pdfwrm_ch06.pdfwrm_ch07.pdfwrm_ch08.pdfwrm_ch09.pdfwrm_ch10.pdfwrm_ch11.pdfwrm_ch12.pdfwrm_ch13.pdfwrm_ch14.pdfwrm_appA.pdfwrm_appB.pdfwrm_appC.pdfwrm_appD.pdfwrm_appE.pdfwrm_index.pdf10. Performance Criteria1. Introduction 2932. Informed Decision-Making 2943. Performance Criteria and General Alternatives 2953.1. Constraints On Decisions 2963.2. Tradeoffs 2964. Quantifying Performance Criteria 2974.1. Economic Criteria 2984.1.1. Benefit and Cost Estimation 2994.1.2. A Note Concerning Costs 3024.1.3. Long and Short-Run Benefit Functions 3034.2. Environmental Criteria 3054.3. Ecological Criteria 3064.4. Social Criteria 3085. Multi-Criteria Analyses 3095.1. Dominance 3105.2. The Weighting Method 3115.3. The Constraint Method 3125.4. Satisficing 3135.5. Lexicography 3135.6. Indifference Analysis 3135.7. Goal Attainment 3145.8. Goal-Programming 3155.9. Interactive Methods 3155.10. Plan Simulation and Evaluation 3166. Statistical Summaries of Performance Criteria 3206.1. Reliability 3216.2. Resilience 3216.3. Vulnerability 3217. Conclusions 3218. References 322wrm_ch10.qxd 8/31/2005 11:57 AM Page 292WATER RESOURCES SYSTEMS PLANNING AND MANAGEMENT – ISBN 92-3-103998-9 – © UNESCO 20051. IntroductionDeveloping and managing water resources systemsinvolves making decisions. Decisions are made at variouslevels of planning and management, even by those whoare simply recommending courses of action to higherlevels of an organization. The ability to make informeddecisions based on scientific as well as social or politicalcriteria is fundamental to the success of any waterresources planning and management organization.Modelling and data management tools can con-tribute to the information needed to make informeddecisions. These tools are quantitative, but they arebased on qualitative judgements about what informa-tion is and is not important to include or consider. Eventhe most ‘objective’ or ‘rational’ of decisions rests onsubjective choices that are influenced by what decision-makers think is important, the objectives or criteria that are to be achieved and for whom, and how muchthey will care. One of the benefits of modelling is thatdifferences in assumptions, in judgements over what toconsider and what not to consider, or about just howaccurate certain information must be, can be evaluatedwith respect to their influence on the decisions to bemade.293Performance CriteriaWater resources systems typically provide a variety of economic, environmentaland ecological services. They also serve a variety of purposes such as watersupply, flood protection, hydropower production, navigation, recreation, wastereduction and transport. Performance criteria provide measures of just how well aplan or management policy performs. There are a variety of criteria one can use tojudge and compare system performance. Some of these performance criteria mayconflict with one another. In these cases tradeoffs exist among conflicting criteriaand these tradeoffs must be considered when searching for the best compromisedecisions. This chapter presents ways of identifying and working with thesetradeoffs in the political process of selecting the best decision.10 Decision-makers and those who influence them arepeople, and people’s opinions and experiences and goalsdiffer. These differences force one to think in terms oftradeoffs. Decisions in water resources managementinevitably involve making tradeoffs – compromising –among competing opportunities, goals or objectives. Oneof the tasks of water resources system planners or managersinvolved in evaluating alternative designs and managementplans or policies is to identify the tradeoffs, if any, amongcompeting opportunities, goals or objectives. It is then upto a largely political process involving all interested stake-holders to find the best compromise decision.Measures indicating just how well different managementplans and policies serve the interests of all stakeholders aretypically called system performance criteria. There are manyof these, some that can be quantified and some that cannot.Lack of quantification does not make those criteria lessimportant than those that can be quantified. Those makingdecisions consider all criteria, qualitative as well as quanti-tative, as discussed in Chapter 2 among others.If every system performance measure or objectivecould be expressed in the same units, and if there wereonly one decision-maker, then decision-making would be relatively straight forward. Such is not the case whendealing with the public’s water resources.wrm_ch10.qxd 8/31/2005 11:57 AM Page 293WATER RESOURCES SYSTEMS PLANNING AND MANAGEMENT – ISBN 92-3-103998-9 – © UNESCO 2005The cost–benefit framework, used for many decades inwater resources planning and management, converted thedifferent types of impacts into a single monetary metric.Once that was done, the task was to find the plan orpolicy that maximized the difference between the benefits and costs. If the maximum difference betweenbenefits and costs was positive, then that was the bestplan or policy. But not all system performance criteria canbe easily expressed in monetary units. Even if monetaryunits could be used for each objective, that in itself doesnot address the distributional issues of who benefits andwho pays, and by how much. While all stakeholders mayagree that maximizing total net benefits is a desirableobjective, not everyone, if indeed anyone, will be likely toagree on how best to distribute those net benefits.Clearly, water resources planning and managementtakes place in a multi-criteria environment. A key elementof most problems facing designers and managers is theneed to deal explicitly with multiple ecological, economicand social impacts expressed in multiple metrics that mayresult from management actions. Approaches that fail torecognize and explicitly include ways of handling conflictamong multiple system performance measures and objec-tives and among multiple stakeholders are not likely to bevery useful.Successful decision-making involves creating aconsensus among multiple participants in the planningand management process. These include stakeholders –individuals or interest groups who have an interest in theoutcome of any management plan or policy. Therelatively recent acknowledgement that stakeholders needto be fully included in the decision-making processescomplicates the life of