Runoff and Sediment Yield Modeling in Meso-Scale Watershed Based on GIS

摘要

While GIS based distributed watershed model is used to study runoff and sediment yield in a micro-scale watershed in the Yellow River Basin, similar research at meso-scale watershed is largely lacking. The upper watershed of Luohe River, a tributary of the Yellow River, was selected as the study area to validate distributed SWAT (Soil and Water Assessment Tool) model with the support of GIS technology. Firstly, the basic GIS database was established for the study area, including DEM, soil, landuse map, weather, and land management data. Secondly, a two-stage “Brute Force” optimization method was used to calibrate the parameters with the observed monthly flow and sediment data from 1992 to 1997. In the process of calibration automated digital filter technique was used to separate direct runoff and base flow. The direct runoff was firstly calibrated, and the base flow, then the total runoff was matched, at last the sediment yield was calibrated. Finally, with the calibrated parameters, the model output was validated with 1998-1999’s observed monthly flow and sediment. Relative Error (RE) was within 20%, Determination Coefficient (R2) and Nash-Sutcliffe Efficiency (Ens) were all equal to or above 0.70 during calibration and validation period. The results demonstrated that SWAT model based on GIS could be successfully used to model long-term continuous runoff and sediment yield in meso-scale watershed in Yellow River Basin