The Hydrology Watershed Model's Application On The Research Of Runoff And Sediment Process

The hydrology model is the outcome of hydrology when it develops to a certain stage, and it enriched the research system and means of hydrology. And along with the developments of hydrology and computer science, the general development of hydrology improved a lot. The conception watershed model of hydrology belongs to mathematics model. Compared with the physics model, it has many advantages, which were looked high widely by hydrologists and hydrology workers. Established in 70's in last century, Xin'anjiang Model has become a pretty mature hydrology model after nearly half century's continuous modification. It obtains successful application in the moist and semi-moist area in moist season. Soil erosion problem is a world problem. The serious soil erosion can worsen the eco-environment, destroy the earth's surface soil layer and descend land's potential produce ability that will affect agriculture production. The eroded material, which gathers together in the river net, become the source of river sediment and silt up on the down side of river。Soil and water conservation is a valid measure to reduce and repress the soil erosion and to protect water and soil resources. But the promise is we must understand the formation, the development and succession regulation of soil and water loss well. The quantity research on soil erosion emphasis on forecasting and estimating the loss quantity of soil erosion and on assessing the velocity and strengths of it etc. The amount of soil erosion is an important index to right evaluate and to synthetically manage soil and water loss, and it is also a ground to establish soil and water conservation measure and carry on regional control plan. Si Chuan basin area is a mound area about 158,000 square kilometers, and the main soil is purple soil. The erosion area and erosion strength is so big and heavy that only next to the loess area in north of China. The erosion rate sometime can above 5897 t/( k㎡·yr), and the erosion area is 77100 square kilometers which occupy 48.8% of the total area. Every year 377 million (about 36.7% of the whole province's soil loss) tons of topsoil will run off, this has become the main obstacle to the further agriculture development in Si Chuan province. Therefore, drawing lessons from domestic and international research result, investigating the soil erosion regulation in purple soil erosion area and building up hydrology and soil erosion model according regional actual condition are necessary to manage soil erosion on sloping fields, control nutrient run off, enhance sloping fields productivity and speed the agriculture economy in the purple soil region. According the testing result from Yanting Purple Soil Research Station of Cheng Du Mountain Disaster Institute of Chinese Academy and Science Institute, this paper did meticulous research to the hydrology processes in that region at two dimensions; With the Xin'anjiang Three Sources Model, we worked out some parameters of this model which fit that area, and obtained some certain results. Through analyzing the relationship between the sand productivity and the land cover and precipitation factor, according ULSE equation and local soils erosion equation, we built up a soil erosion empirical formula and meanwhile supplied scope of parameters; Also we put forward the concept of sediment unit line and got quite good simulation result when applied it to this area.