Research on runoff simulation of TOPMODEL based on grid size

In order to explore the effection on runoff simulation of distributed hydrological model under difference grid size, this paper carry on runoff simulation with improved TOPMODEL distributed model. It is selected to verify runoff simulation under 90m, 500m and 1000m in grid-scale Separately that ten great floods and ten small floods observed data sets arrive from Tiantou River. Results show that the smaller grid size is adopted, the higher accuracy is achieved considering well-distributed of rainfall in the whole basin. And 90m grid-scale have been able to produce more accurate simulation results.