APPLICATION OF AN INTEGRATED BASIN-SCALE HYDROLOGIC MODEL TO SIMULATESURFACE-WATER AND GROUNDWATER INTERACTIONS

Hydrologic models have become an indispensable tool for studying proce sses and water management in watersheds. A physically-based, distribut ed-parameter model, Basin-Scale Hydrologic Model (BSHM), has been deve loped to simulate the hydrologic response of large drainage basins. Th e model formulation is based on equations describing water movement bo th on the surface and in the subsurface. The model incorporates detail ed information on climate, digital elevation, and soil moisture budget , as well as surface-water and ground-water systems. This model has be en applied to the Big Darby Creek Watershed, Ohio in a 28-year simulat ion of rainfall-runoff processes. Unknown coefficients for controlling runoff, storativity, hydraulic conductivity, and streambed permeabili ty are determined by a trial-and-error calibration. The performance of model calibration and predictive capability of the model was evaluate d based on the correlation between simulated and observed daily stream discharges. Discrepancies between observed and simulated results exis t because of limited precipitation data and simplifying assumptions re lated to soil, land use, and geology.