Improvement of a Coupled Land Surface-Hydrological Model with Calibrated Hydraulic Parameters

Topographical and hydrogeological information in the Huaihe River basin are used to calibrate the manning's roughness and hydrologic conductivity parameters in the Coupled Land Surface-Hydrological Model version 1.0 (CLHMS1.0). The impacts of these two parameters on the model performance in simulating the observed hydrological processes over the Huaihe River basin are investigated by different sets of sensitivity experiments using the CLHMS1.0. It is revealed that a decrease in manning's roughness in the Wangjiaba sub-basin leads to a significant increase in the simulated water flow velocity, which in turn improves the model simulated peak time of streamflow at Wangjiaba station. Meanwhile, a more reasonable database for hydrologic conductivity over the Huaihe River basin will lead to improvement of the model's capability in simulating the observed magnitude of the streamflow. The daily streamflow hydrograph in the Huaihe River basin during 1980-1987 is simulated using the improved CLHMS with calibrated manning's roughness and hydrologic conductivity parameters, it is found that the improved CLHMS1.0 can more accurately simulate the observed daily hydrological process. Moreover, the relative contributions of surface runoff and underground water supply to the observed streamflow in the Huaihe River basin have been more reasonably simulated by the improved model when compared with the observation.