The Runoff And Conflux Simulation Research In Watershed Based On GIS

In this thesis, a watershed conceptual rainfall-runoff distributed hydrological model is developed based on the Geographical Information System (GIS) technique and Digital Elevation Model (DEM). With the model and GIS being relaxed coupling with each other, the net rain fall of the drainage area and its floodwater process at the outlet can be figured out by programming. The simulative precision of the model can also be analyzed. The result indicates that the modeling system can be adopted in the Lay runoff and conflux simulation to the drought and half-drought region.In the thesis, digital drainage net was extracted by spatial analyst model of Arcgis9.0 and drinage module of WMS70. Aiming at the plainness region of DEM, the thesis adopts changing plainness grid cell direction and altering the flow direction of parallel runway by contrast to the practice of the river net. This makes the adopted water system accord with the instances of the real drainage area. For the setting off of the sub-watershed, with the differentiate ratio of DEM, the terrain and area of real drainage area, the amount of calculation of the model, and the cumulative error, the drainage area is divided into 29 spontaneous sub-watershed. Each sub-watershed is relatively a closed catchment section and accords with the circumstance of the established model. According to the slope direction, each sub-watershed is divided into two calculating units, the sunny slope and the sunless slope, the lay runoff model is established. So the flow of the outlet of the sub-watershed can be calculated through figure of conflux and through river way conflux model. Of which, the Lay Runoff model adopts the SCS model, the conflux of those sub-watersheds zero dimension unit graph, and the conflux of river way Muskingum method. According to the conditions of the sub-watersheds, the parameters of all the models and the features of its groud cover can be fixed on and calculated sub-watershed parameters are ascertained so that the solutions of the model can be calculated by programming.By comparing the computational solutions of the model with the field measurements in 20 floodwaters, the eligible rates of both Lay runoff and conflux come to above 70%. The flow duration curves at the outlet accords with its experimental ones, indicating that the extracting to river net, dividing of sub-watersheds, processing of the data of rainfall, and selecting and calculating of the models in this thesis are reasonable.