Development And Application Of Grid-Based Distributed Xinanjiang Model

With the development of modern hydrology, computer technology and 3S (Remote Sensing, Geographical Information System, Global Position System) high-tech, distributed Hydrological Models based on DEM (Digital Elevation Model) are becoming the new trend of Hydrological Models. In this thesis, based on DEM, the methods of extracting basin information are studied and summarized, such as drainage network, river system, flow length and so on. Then, according to the theory of the Xinanjiang model, the Grid and TOPography-based distributed Xinanjiang model (Grid-Xinanjiang) is developed.Grid-Xinanjiang model takes every DEM unit grid as a sub-basin, using the initial Xinanjiang model to calculate runoff-yield of the current grid, then, according to the calculation order among the DEM grids, the flow of the outlet of each grid to the outlet of the whole basin is routed by the grid-by-grid method of Muskingum. When calculating the runoff-yield and runoff-concentration in every unit gird, the water balance and influence of the river drainage network are taken into consideration. In other words, in the calculation of the runoff-concentration, first, considering whether the current grid is saturated. If it is not, the soil water content of this grid will increases due to the outflow of the upstream grids before the soil moisture of it reaches water storage capacity. Moreover, if there is a channel in unit grids and because of the effect of the drainage network, not all the overland inflow and interflow flow into the downstream grid, part of them will flow into the channel.In order to verify the applicability of the Grid-Xinanjiang model, this model is applied to the Misai basin of which is a branch of Qiantangjiang River. Meanwhile, the initial Xinanjiang model, TOPMODEL and GTOPMODEL are used to compare with it. Results show that four models are suitable to this basin and the Grid-Xinanjiang model performs well than others in the simulation accuracy.