Analysis Of Danjiangkou Inflow Runoff Based On ArcGIS Desktop

South-to-North water diversion project which accomplished inter-basin water diversion plays an important part in the solution of water shortage in northern area. As the water source of the middle water transfer line of South-to-North water diversion project, the inflow of Danjiangkou Reservoir and its variation law directly affect water amount can be conducted and the water supply guarantee rate in the project. This paper studied the inflow and impact factor of Danjiangkou Reservoir by using geographic information system software (ArcGIS Desktop).The paper analyzed and compaered several basin mean annual precipitation calculation methods. In consideration of the geographic and environmental feature in Danjiangkou basin, the author calculated the mean annual precipitation of the basin using Theissen polygon method on the assistant of ArcGIS software and then compared the result of this method with that of cell method. The comparation validated the accuracy of this method. Then the paper analyzed the interannual variations of precipitation in Danjiangkou basin.In the analysis on impact factor of inflow of Danjiangkou, the paper introduced several factors that can affact basin runoff and respectively analyzed the precipitation, Climate and land use, which are three of the factors can affect inflow of basin, in Danjiangkou basin with reference to historical data of this area. After the analysis, the paper concluded that precipitation is the main factor impacting the inflow of Danjiangkou basin.On the premise of full understand of home and abroad study condition, the paper chose SWAT model to analyze the inflow of Danjiangkou basin and constructed SWAT model on ArcGIS platform. On the basis of the model, the paper analyzed the interannual variations of inflow to the variation of precipitation in Danjiangkou basin and explained the result.The result indicate that ArcGIS desktop possess obvious advantage in the research hydrology. Theissen polygon method in ArcGIS provides a convenient to precisely calculate the mean annual precipitation and can visually display the result. SWAT model analysis the impact of climate condition to runoff in basin on the basis of the physical process of water circulation. This simulation method possess a high accuracy. The inflow of Danjiangkou reservoir vary according to the variation of precipitation and the its variation extent is bigger than that of precipitation. This can provide imformation for the rational, scientifical and safe water transfer.