Ken Nowak, Alan Butler, Carly Jerla (Bureau of Reclamation—Lower Colorado Region), Jim Prairie (Bureau of Reclamation—Upper Colorado Region)

Abstract: The purpose of the Colorado River Basin Water Supply & Demand Study (Study) is to assess future water supply and demand imbalances in the Colorado River Basin over the next 50 years and develop and evaluate options and strategies to resolve those imbalances. To address the considerable amount of uncertainty in projecting the future state of the Colorado River system, the Study has adopted a scenario planning approach that has resulted in four water supply scenarios and up to six water demand scenarios. In order to assess the various potential future imbalances, each combination of supply and demand will be modeled using the Colorado River Simulation System (CRSS), Reclamation’s long-term planning model for the Basin. A broad range of options and strategies will subsequently be incorporated in CRSS and modeled individually to evaluate their unique capacity to mitigate future imbalances. Several “portfolios” will then be crafted by combining options and or strategies to achieve a particular objective in light of the projected imbalances (e.g. reliability, cost-effectiveness, etc.). Last, portfolio performance will be tested against the various supply and demand combinations. All totaled, we estimate the potential for over 1,500 CRSS runs. Until recently, this volume of modeling would have been impossible given the Study timeline. However, due to advances in RiverWare, coupled with enhanced computing capabilities, this workload is well within reason. Distributed multiple run management drastically reduces the computing time of the many combinations and the study manager streamlines manipulation of run configurations and input/output data.