ON EVALUATING PAST 20,000 YEAR CLIMATE CHANGE IN THE GREAT BASIN WITH A COUPLED CATCHMENT-LAKE MODEL

Estimation of groundwater recharge and prediction of future climate change require evaluating paleoclimate records. Owens Valley, California, a hydrologically closed basin within the Great Basin, is one of the best locations for studying continental paleoclimate change, because it has the most completed Quaternary paleoclimate records in the world. The sedimentary and geochemical studies on the lakes in the Owens Valley reveal that the past changes in lake levels recorded the paleoclimatic changes in this region. In this study, a coupled catchment-lake model has been developed to evaluate how the hydrology responds to climate changes (mean annual temperature and mean annual precipitation) in Owens Valley since the last glacial maximum (LGM). The model includes three major components: basin module, catchment hydrology module, and lake module. The basin module is used to derive basin geometry from the digital elevation model (DEM). The catchment hydrology module includes surface and subsurface flow processes and their interactions with lakes. The lake module, an energy and water balance model, is used to compute water budget of the lake. The 500 m DEM and simulated results with a regional climate model that is based on boundary conditions provided by the global circulation model are used to drive the catchment-lake model. Simulated results compare well with the results from previous studies through macrofossil, sedimentary, and geochemical records.