The Study Of Flow Simulation In The Three Gorges Area

With the beginning of the Changjiang Three Gorges Water Conservancy Hinge Project, it had been paid the most attention by all people over the world that the project had been affecting the development of social economy and the status of natural environment in the area of the Three Gorges. And, soil erosion and non-point source pollution are the two reasons, that the deterioration of the environmental quality is threatening the human survival and development in the world. Rainfall-runoff simulation is the very important technique for soil erosion, non-point source pollution, surface water balance calculation and some other study fields.With the development of computer technology and some cross knowledge, the study method of watershed hydrological simulation has changed ultimately. The outstanding trends are that computer technology, spatial technology and remote sensing technology are applied in hydrological model and distributed physical hydrological model is brought about widely. In the hydrological simulation, RS and GIS technology bring innovation for the traditional study methods. Digital elevation model (DEM) technology provides stable foundation for the development of digital hydrology and the naissance of the digital hydrological model in particular. DEM has abundant information about terrain, and we can extract the watershed basic characters, which include land surface characters, drainage network et al based on GIS, and also can make certain the watershed boundary and set off sub watersheds from DEM, which provide the flat roof for digital hydrological simulation.The area of Three Gorges as an example, this study constructed digital basins of the Three Gorges and extracted basin digital characters from DEM, and simulated rainfall-runoff with the rainfall-runoff model. The main contents and results include:(1) The spatial subject database building up. Windows 2000 Professional was used here for operating system, and ArcGIS 9 from ESRI Company was used for the work flat floor. This database was build up, which includes digital elevation model, basins drainage network, soil, land use et al. In this study area, woodland, paddy field and dry land are the main types in land use. The agrotype in Chongqing mainly include yellow soil, paddy soil, purple soil and calcareouse soil.(2) Discussing the method of extracting and modifying drainage networks. This paper discusses the methods and elements on extracting drainage network based on DEM, and the study area is the region of the Three Gorges in Chingqing. The "burn-in" method is used to process the DEM once more, that the true stream network could be split to the DEM in the plate area where the automatic stream network is different from the true one. Then the elevation values of the grid units were modified, and the stream network of the watershed was generated again. With the modification not too much, the generated network matched up to the true one better. Meanwhile, the veracity of...