Simulation Research Of Rainfall Runoff In River Basin Based On GIS Technology

Rainfall runoff is a kind of runoff that is Tableed by rainfall,which joins the river net and merges at the section of the basin through the surface or underground action. The Tableation of rainfall runoff is quite complex since it is limited by so many factors such as rainfall, geological,geographic,and geomorphic conditions,soil,vegitation,land utilization,human activities and so on.Research on rainfall runoff has been the focus and hot spot of hydrological field for a long time. The rainfall-runoff model has been applied to more and more fields,like flood control and disaster mitigation, water resource sustainable utilization and protection and rehabilitation of water ecosystem.And it is also an effective tool to analysis and study the influence on floods,water and soil erosion, water resource and environment,brought by climate changes and human activitiesThe landTable of Minjiang River valley is quite complex and its terrain units changes greatly. It has fragile ecology,prone mountain hazards, high watershed sediment yield and vegetation coverage. A s the green barrier of ecological safty, Minjiang River valley is of great significance to the ecological safety of Chengdu plain, Sichuan Basin,Yangze River,and even the vast developed eastern areas.This paper takes the upstream sub-basin of Minjiang River as the case study area. Hydrological m odule in ArcGIS9.3 Spatial Analysis Tool has been applied to the extraction of DEM of the drainage patterns in the upstream of Minjiang River,according to the Digital Elevation Model, land ultilization,soil type,annual rainfall and other data. The threshold of the drainage area is determined by the relationship between the threshold and the drainage density and the source density.Deviding the valley into several sub-basins and take one as case study area,then devide the area into different hydrological response units(HRU)according to land ultilization and soil types. The rainfall runoff and its runoff coefficient is obtained through combining the exsiting physico-mathematical model and the annual rainfall data.And at last the research achievement and outlook is put forward. The main results of the paper are as follows:①Based on watershed runoff theories, using ArcGIS software analyzes the hydrologic information, determine the catchment area threshold and hydrological response unit, the results showed that the method of directly extract drainage and terrain parameters information basin by DEM is feasible; ②Use GIS spatial analysis method, case study area of simulated rainfall runoff , get the annual rainfall runoff coefficient variation of study area;③Compared numerical calculation with runoff GIS spatial analysis simulation, the results were consistent.