Simulating the Soil Moisture and Runoff in Baohe Catchment Based on TOPMODEL and DEM

TOPMODEL, a rainfall-runoff distributed physical concept frame to simulate hydrological process in watershed or slope mathematically, has been proposed for decades. This paper combines the new geo-information system (GIS) and this model to simulate the soil moisture and runoff in a Baohe River basin. Based on the 90 m-resolution grid-based digital elevation model data, the digital drainage network is generated to simulate the stream flow processes and the soil moisture distribution. The years from 1981 to 1983 are selected as the calibration period and the years from 1984 to 1985 are selected as the verification period for daily stream flow simulation. Nash-Sutcliffe efficiency is utilized to evaluate the performance of TOPMODEL. Through the above-mentioned studies, primary conclusions can be drawn that the Nash-Sutcliffe during the calibration period is 87.10% and during the verification period is 78.06%. And the soil moisture distribution simulated by TOPMODEL is agreement with the field observation, which suggest that TOPMODEL can be used as a soil moisture prediction tool and hence as an agricultural drought forecasting tool.