Numerical Simulation Research On The Influence Of Watershed Topography On The Process Of Rainfall And Runoff

In recent years,due to the uneven spatial and temporal distribution of rainfall,flood disasters in the river basin occur frequently,which has brought great threats to the development of national economy and the safety of life and property.Watershed flood is one of the natural disasters with the greatest destructive power and the widest influence range.Timely and effective flood prediction is the main scientific means to avoid disaster.Hydrological model is the premise and foundation of watershed flood prediction.The accuracy of model prediction mainly depends on the quality of topographic data of the input model.The higher the topographic accuracy of the input model,the better the simulation results can represent the real surface confluence.However,high precision terrain has high requirements for computing facilities,and it is difficult to obtain data.Therefore,it is of great significance to study the correlation between rain-flood process and DEM resolution,establish a set of runoff conversion model which can infer high-precision topographic flow process from low-precision topographic data,and accurately simulate the watershed which lacks fine topographic data.Based on topographic factors,this paper carried out a study on the response relationship between rainfall-runoff process and landforms with different DEM resolutions in Wangmaogou,Baogaisi watershed and Gangu topography,and mainly drew the following conclusions:(1)Under the same design rainfall condition,when the accuracy of topographic data decreases,the peak flow of exit section simulated by GAST model decreases gradually;Under the condition of the same topographic resolution,the peak discharge of the exit section increases with the increase of the design rainfall return period.(2)extraction is analyzed to describe the form the core of the information the terrain factor,found that the slope,the surface roughness of DEM resolution,the core of terrain factors such as reduced,the terrain ups and downs,vertical variation coefficient,core terrain factors such as surface curvature on the rise,with the decreasing of DEM resolution terrain elevation factor with the terrain resolution changed little;(3)Based on the spatial analysis of the core topographic factors,the 12 core factors were integrated into three main topographic factors to represent the geomorphic information,namely,topographic elevation difference and relief factor,topographic mature-energy interaction factor,and topographic concave-convex change factor.(4)Based on the rainwater process simulated by the main topographic factors and GAST model,a DEM-runoff transformation model is established.Through comparison,the ERMs of the flow process obtained from the conversion are all less than half of the standard deviation of the flow process simulated by the model,which indicates that the proposed conversion model has great application value.