Study On Runoff And Sediment Of Distributed Model In The Loess Plateau Based On DEM

Our country's economic sustainable development is constrained by water shortage,soil erosion and destruction of the regional ecological environment,etc,in long-term. The studies of watershed runoff and sediment model more focus on the lumped model and the conceptual model in our country, and fall behind the other developed countries. With the continuous development of our country's economic construction, the traditional lumped and conceptual model can not meet the needs, and need to research more advanced distributed model. Distributed watershed runoff and sediment model can not only help people to understand extensively the hydrological cycle and watershed sediment yield in different spatial and temporal scales, but also supply an effective framework and platform to slove the problems related to the hydrological cycle and soil erosion in practice, and support important evaluation tools and effective technical to solve water source, water pollution, water environment, water and soil erosion etc.The distributed model is established according to the mechanism of slope runoff and sediment yield, based on DEM terrain extraction and investigating the Chabagou watershed. The main results are as follows:1) By the preliminary field investigation,the typical spatial distribution of study watershed's topography,soil characteristics,vegetation type,land use and soil erosion situation and pattern are understanded directly.2) According to the Loess Plateau runoff characteristic and the basic principle of runoff erosivity to calculate the slope runoff and sediment yield, and build the slope runoff and sediment model. Using of the separate parameters and coupling between the runoff and sediment to build the DEM-based distributed watershed model, based on the D8 algorithm and Muskingum method.3) The models with two different spatial scales are calibrated by using the monthy averaged data of from 1959 to 1969.While the surplus monthly averaged data from 1970 to 1989 are used to validate the two models.The validation and calibration results show the calculation results are general fit to the measured data and it can be applied to solve related problems.4) The calculation result from the model with grid cell have higher precision. Moreover,the spatial distributions of the watershed runoff and sediment yield can be calculated with the DEM grid cell based model. The calculation results show the distributed trends between the runoff and sediment are similar each other. Lastly,The Grid-based distributed watershed model is modified to think about the facters related to engineering measures,and the results from modified model is improved at some degree.