Water Management Decision Making in the Face of Multiple Forms of Uncertainty and Risk

In the Wasatch Range Metropolitan Area of Northern Utah, water management decision makers confront multiple forms of uncertainty and risk. Adapting to these uncertainties and risks is critical for maintaining the long‐term sustainability of the region\u27s water supply. This study draws on interview data to assess the major challenges climatic and social changes pose to Utah\u27s water future, as well as potential solutions. The study identifies the water management adaptation decision‐making space shaped by the interacting institutional, social, economic, political, and biophysical processes that enable and constrain sustainable water management. The study finds water managers and other water actors see challenges related to reallocating water, including equitable water transfers and stakeholder cooperation, addressing population growth, and locating additional water supplies, as more problematic than the challenges posed by climate change. Furthermore, there is significant disagreement between water actors over how to best adapt to both climatic and social changes. This study concludes with a discussion of the path dependencies that present challenges to adaptive water management decision making, as well as opportunities for the pursuit of a new water management paradigm based on soft‐path solutions. Such knowledge is useful for understanding the institutional and social adaptations needed for water management to successfully address future uncertainties and risks

An assessment of exceedance probabilities of envelope curves

Envelope curves are often used to provide summary accounts of our flood experience, but their operational use has been limited by our previous inability to assign to them an exceedance probability ‘‘EP.’’ General expressions are derived for the EP of an envelope curve at a particular site in a heterogeneous region, as well as measures of central tendency of EP across sites. Analytic results are reported for the case when floods follow a Gumbel or generalized extreme value distribution, and these results are contrasted with those of previous studies that sought to estimate the exceedance probability of extraordinary floods such as the flood of record (FOR) and the probable maximum flood (PMF). A case study involving FOR and PMF discharges for 226 rivers across the U.S.A. indicates that relatively consistent estimates of the average exceedance probability associated with both FOR and PMF envelope curves can be obtained using the theoretical approach introduced here