ON EVALUATING DENSITY DRIVEN GROUNDWATER FLOW IN THE CLOSED BASIN

The closed basin hydrologic and geochemical cycles in arid regions are subjected to the climate variability over a wide range of spatial and temporal scales, which directly link to the magnitude and frequency of severe regional flooding events. Improved understanding of such a variabilty will help minimize the termendous damages caused by extreme hydrologic events (e.g., floods) to human lives, economic activities and natural resources, and help manage water resources efficiently. The topographic and geologic data collected in the Pilot Valley, Utah are used to conceptualize the closed basin hydrologic domain. Saturated and Unsaturated Transport model (SUTRA) is then implemented in the Pilot Valley to simulate subsurface density-driven flow with rainfall-induced recharge at high mountain areas and discharge at the low valley playas. Historic meteorological records (i.e., precipitation, temperature, and solar radiation) and digital elevation data are compiled and analyzed for the hydrologic simulation with SUTRA. The relationship function between elevation and precipitation is constructed and used for estimating the rainfall induced recharge to the groundwater. Numerical experiments are designed to examine how the heterogeneity in geologic formations (e.g., hydraulic conductivity and storativity) and the scaling variability in topography affect the flow system. The impact of climate variability (warm and wet trends) on the closed basin flow system is evaluated with the simulation.