Decision-Centric Adaptation Appraisal for Water Management Across Colorado's Continental Divide

Drought episodes occurring in a warmer future climate may threaten water supplies for cities and farms along Colorado's Front Range by reducing their ability to divert water across the Continental Divide from the Upper Colorado River Basin. A multi-step decision support process was developed and applied to the physically and legally complex case of Colorado's transbasin water diversions. We illustrate our approach by simulating the performance of an existing drought-response measure, the Shoshone Call Relaxation Agreement (SCRA) using the Water Evaluation and Planning (WEAP) hydrologic cycle and water systems modelling tool and the Statistical DownScaling Model (SDSM-DC) stochastic climate scenario generator. Scenarios relevant to the decision community were analyzed and results indicate that this drought management measure would provide only a small benefit in offsetting the impacts of a shift to a warmer and drier future climate coupled with related environmental changes. The analysis demonstrates the importance of engaging water managers in the development of credible and computationally efficient decision support tools that accurately capture the physical, legal and contractual dimensions of their climate risk management problems.