Sensitivity Analysis Of Regional Soil Erosion Model

According to the research achievement of soil erosion model and large-scale hydrological model home and abroad, based on the process of the regional soil ersion ,and the development of GIS, Remote System, and computer technology, the regional soil erosion model was preliminary established. The regional soil erosion model is not only an effective tool for regional soil erosion survey, but also of great importance for soil and water conservation policy-making. Regional soil erosion model based on cell size to analysis the regional soil and water loss process.The monthly precipitation was assumed as a single rainfall event, divided into several periods and was taken as an input for model operation. Accumulation of runoff and sediment among units was calculated by means of a spatial analytic function within GIS. The model simulations are affected by different cell size and time step. Yanhe River was selected to study,to analysis the simulation result under the different cell size and time step deciding the appropriate cell size and time step .Parameters of regional soil erosion models describe the watershed features and affecte model simulations .It is very important to analysis the sensitivity of parameters. The main results are as follows:1. Determine cell size. Analysis the simulation results by operating regional soil erosion model under different cell size. The result shows that bigger cell size, the smaller simulation value of slopes, surface storage in micro-depressions, runoff velocity and transport capacity which result to affect sediment yields and the time of operating model. The sediment yields of the 400m cell size decreased 10% compared with the 50m cell size. The decreasing tendency of sediment yields is same as the slope under different cell size. The operating time of model is great influence by the cell size .As a result, the 100m cell size is an appropriate calculation unit for the regional soil erosion model.2. Determine time step. Using the precipitation data in July 1995, the duration of rainoff is 800min, divided into several periods and was taken as an input for model operation to analysis the simulation result.The result show that the shorter time step,the less simulation value of the runoff depth ,sediment yield ,denudation quantity, runoff and the longer time of operating model. The simulation result has a significant change in the 200min time step. To consider the efficiency of model running and simulation result, 200min is the appropriate time step for the model.3. Sensitivity analysis. Using single-factor disturbance method, analysing the sensitivity of input parameters .The experiment show that rainfall is the most sensitive parameter to the sediment yield and runoff; the resistance coefficient is less sensitive than rainfall to the sediment yield, the infiltration rates is little effect on runoff, no sediment yield; The leaf area index has very little effect on the sediment yield and runoff...