Water Policy (Dec 2021)
Screening for nonstationary analysis
Abstract
Adjustments in the designs of water resources systems due to climate change and other nonstationarities are warranted because the benefits of effective adaptation are well recognized. Therefore, the time and resources invested in these analyses are well worth the effort. Before a major investment in an effort is made, however, it is reasonable to determine if the problem is of sufficient complexity or the value of additional information is high enough to warrant the inclusion of complex, sophisticated methods that explicitly include nonstationarity and associated decision-making under deep uncertainty. There exist several planning level conditions such as the lifetime of the project, its criticality, and its reversibility that may indicate detailed analysis is not needed. There are also sequential analysis and screening steps that can be applied to determine the complexity of the methodology needed. Finally, the use of decision analysis can also help determine if additional, detailed analysis, or data collection are necessary. The use of one or several of these methods should be considered as initial steps before undertaking a vulnerability assessment and developing an adaptation strategy for a water resources system. HIGHLIGHTS Including nonstationarity in the design of water resources systems may require considerable resources and finances to apply but given the high cost of failures of most water-based systems and the generally high benefit–cost ratios of adaptation, the expense and effort of appropriate planning are certainly justified. There are circumstances, however, when even though nonstationarity is acknowledged, a full detailed assessment of it is not necessary.; The decision on the complexity of the analysis can be based upon a project's lifetime, criticality, reversibility, flexibility/adaptability, robustness, and the use of forward design standards.; Top-Down and Bottom-Up screening methodologies also exist to assist in the analysis decision. Some rely upon determining if a system is operating below capacity and/or its historical performance, assessing the climate sensitivity of the needs of stakeholders, and changes in the design conditions.; Several recent methods such as the World Bank Decision Tree Process and Climate Risk Informed Decision Analysis (CRIDA) include screening as part of their complex processes.; The use of decision analysis can help determine if additional, detailed analysis, or data collection are necessary.;
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