James VanShaar, Marc Baldo and Jay Day (Riverside Technology, Inc.)

Abstract: Water managers are faced with planning to meet future water supply demands under a very uncertain climate future. Riverside Technology, inc. has developed a web-based Climate Change Decision Support System (DSS) to address the needs of these water managers who are often faced with conflicting information about climate change for their area of concern and no real basis for determining its impact on water resources.
     The Climate Change DSS provides display tools to help water managers explore the range of temperature and precipitation changes projected by different Global Circulation Models (GCM). The system uses downscaled GCM data as input to small-scale watershed models to produce time series of climate projected water supplies for various emission scenarios and GCM simulations. To assess the impact of climate change on water resources operations, the climate-adjusted flows must be coupled with operations models to predict changes in water system decision variables (e.g., magnitude, frequency, and duration of shortages; hydropower generation; and flood control storage).
    Riverside applied climate-adjusted streamflow time series from the Climate Change DSS to the Colorado River Simulation System (CRSS) RiverWare model. CRSS models the Colorado River Basin using twelve reservoirs, some of which represent the combined storage of several smaller reservoirs and approximately 115 applications of water to irrigation and other uses. Results will be presented describing changes in: total inflow to the system; yearly outflows from Lake Powell; outflows below Imperial Dam; January 1 total system storage; yearly evaporation from the reservoirs; and energy produced at the hydropower plants associated with modeled dams.