Role of run-on process of overland flow on hydrological modeling

In this paper,a grid-based kinematic wave Xinanjiang model is developed and the structure of the original Xinanjiang model is downscaled and modified accordingly.The basin is subdivided into raster network.The raster slope and flow vectors are extracted by the software package,DigitalHydro based on DEM.The Xinanjiang model is used for calculating runoff in each raster and the kinematic wave method is used for overland flow routing.In each grid,water input to the model includes precipitation and runoff from the upstream grids to take runoff infiltration(i.e.run-on mechanism) into account in runoff calculation module.In the kinematic wave model,the Manning coefficients are determined according to the land cover information and the flood grade.The Huangnizhuang sub-basin with an area of 805 km2 in Shiguanhe basin,Huaihe River is selected as the studied area.It is shown that the run-on mechanism has an important effect on the runoff prediction and it also affects the spatio-temporal distribution of the soil water storage.The results show that the predicted flood peak without consideration of the run-on mechanism will be lagged.