Research On Heterogeneity Of Runoff And Hydrodynamics Process Simulation Of Nesting Watershed In Loess Plateau In West Shanxi Province

Relation runoff and sediment of the Loess Plateau is the focal problem in scientific community. Relying on project of "regulating of transition and differentiating of agricultural water and soil resource and eco-environment adjusted and controlled by forest-cover"(2002CB11503) , supported by National "973" foundation, on base of the data derived from national Jixian ecological experiment station, and experiments on the spot, spatial and temporal distribution, movement mechanisms of water in nested watershed of the Loess Plateau in West Shanxi Province are analyzed and discussed broadly and deeply. The results can be important theoretic and practical basis for the sustainable watershed management and rational utilization of water resources of the Loess Plateau.1. Average rainfall in research site is 579.5 mm per year and 90 percent falls in during from April to October. The erosion rainfall intensity is more than 10 mm per hour on site. The precipitation is cyclical variation.2. The curve of soil moisture feature is researched. The soil moisture capability and the saturated hydraulic conductivity of forest of natural second growth is highest in all site types.3. The infiltration speed rate of shrub stands are highest. The soil physical feature, initial soil moisture, slope, slope site, rainfall intensity and vegetation can effect the stable soil moisture infiltration speed rate and initial runoff time.4. Soil moisture infiltration can be simulated well by Philip soil moisture infiltration model. The contour chart of soil moisture infiltration of single small watershed is constructed by simplified Philip infiltration model and Pedo-Transfer Functions. 5. Rainfall intensity can effect runoff speed rate and runoff amount, but amount of precipitation cannot influent runoff. Law of interception of forest canopy is studied. It is power function relation between interception of canopy and amount of precipitation, amount of interception can change by months. There are obvious relation between amount of interception of litters and amount of precipitation.6. The use of physical course of runoff initiation, the comprehensive model of rainfall-infiltration-runoff is constructed. Through the results of comprehensive model, gully is the main position of runoff occurrence.7. The use of MMS model, the hydrographic course can be simulated in nested watered in the Loess Plateau.