HydroGeoSphere is an excellent tool for evaluating climate change impacts to integrated hydrologic systems, since HGS can be effectively coupled with climate forecasting simulators like the Weather Research and Forecasting (WRF) model, the Community Climate System Model (CCSM) and the Canadian Regional Climate Model (CRCM). HydroGeoSphere accounts for water dynamics in the atmosphere, ground surface and subsurface in a seamless manner and thus is the best modeling tool for evaluating the impact and risk associated with climate change on water resources.