By Carly Jerla, & Paul Miller (Bureau of Reclamation, Lower Colorado Region)

Abstract: Streamflow projections by Bureau of Reclamation (Reclamation) have traditionally been based upon historical streamflow records and have assumed that future mean streamflow and variability is adequately represented through past observations. As climate change research continues to advance, the assumption that past flows are indicative of future flows may no longer be valid; to this end, Reclamation is currently investigating how to best incorporate projections of future climate into operational and policy models. The World Climate Research Programme’s (WCRP’s) Coupled Model Intercomparison Project phase 3 (CMIP3) multi-model dataset has recently been made available through a joint effort between Reclamation, Santa Clara University, and the Lawrence Livermore National Laboratory and provides statistically downscaled climate projection data from a myriad of climate models over the continental United States. Through cooperation with AMEC and the Colorado Basin River Forecasting Center (CBRFC), Reclamation is working to develop projections of streamflow throughout the Colorado River Basin using the Variable Infiltration Capacity (VIC) and CBRFC River Forecasting System (RFS), respectively, forced with data from the WCRP CMIP3. These streamflow projections are then used to drive Reclamation RiverWare based models to assess potential impacts to reservoir impacts under changing climate conditions.