Abstract:

This paper used the Poyang Lake watershed as the study area, and a distributed hydrological model was set up for this area The observed river discharges at six main hydrological stations from 2000 to 2005 and the base flow index of groundwater were used to establish the objective functions for coupled model optimization PEST was used as an autocalibration tool embedded in WATLAC to improve the efficiency of model calibration Results showed that the Nashsutcliffe efficiency coefficients of different hydrological stations were varied from 071 to 084, and coefficients of determination were varied from 070 to 088, a better simulation effect was gained The actual evapotranspiration （ETa） based on remote sensing was further used to validate the model  Results indicated that model simulated and remotely sensed ETa match well in terms of the spatial variation pattern and the temporal change trend Furthermore, groundwater flow model was estimated qualitatively, and it was found that the spatial variation of water table was in consistent with the land surface elevation The general flow direction was from the mountainous areas to the plain area, which was judged as reasonable The model calibration strategy and technique proposed in this paper can provide high reference for similar studies in a large scale watershed simulation and parameter calibration.