On evaluating the spatial-temporal variation of soil moisture in the Susquehanna River Basin

The Hydrologic Model System (HMS), a physically based distributed model, wa s used to simulate the soil moisture variation during a storm event in the Upper West Branch, a subbasin of the Susquehanna River Basin. The model was calibrated by comparing the simulated temporal daily variation in soil moi sture with field data. Data from the Mahantango Watershed within the Susque hanna River Basin were used to drive the HMS for the temporal simulation of soil moisture as a function of soil texture, vegetation, and topography. S patially distributed data sets with a resolution of 1 km were prepared for the simulations and used to examine the soil moisture variation as caused b y the spatial variability in soil texture, vegetation type, and topography. The Pennsylvania State-National Center for Atmospheric Research Mesoscale Meteorological Model (MM5) coupled with the HMS was used to simulate the ba sin response of hydrologic processes to a storm event. The effect of infilt ration on the soil moisture along the flow pathway in the river basin and t he overall hydrologic response with observed precipitation compare well wit h observations. The simulated hydrologic response with the MM5-simulated pr ecipitation slightly underestimates the actual response.