The Characteristic Research On Rainfall And Runoff In ShannXi Of WeiHe River Basin

With the rapid development of Shaanxi area alongside the Weihe River, plenty of industrial wastewater and domestic sewage discharge into the river without treatment. At the same time, for the natural condition and climate, with the result of the little area rainfall and the little runoff in Weihe River, river self-purification descends, and the water quality becomes worse. To improve the self-purification ability and pollution situation of river water, control the pollution load and ensure the river basic flow are two important ways. It is meaningful to find out the relationship between the two factors and the runoff of Weihe River, which are rainfall and pathway. Experience-frequency curve was used in the simulation of rainfall to analysis the rainfall characteristic of this area; runoff was simulated by association of SCS model and GIS technology, to study the pathway identity.Experience-frequency curve was used in the simulation of rainfall at different probability, and according to the linear dependence relation between rain capacity and raining days. The simulation result shows that the rain capacity is only 567 mm when P is 50%,the rain capacity are 736 mm and 409mm when P are 10% and 90%, and focus between June and September that takes 57% of the total annual rainfall. The most of continuum raining days is 17, and the amount of the rainfall is 165.7 mm when P is 0.01%.It is an important study on the area pathway where is lack of data and information. With the SCS model parameter calculated by the agrotype, the factors of sing mode of land and the level of soil wetness with the help of GIS are used to estimate the parameter of SCS model. Runoff simulation shows that precipitation rainfall directly affects therunoff usually, and the level of soil wetness and ground line gradient affect the runoff obviously when continuum raining or continuum drought.