The Research Of Hydrological Simulation On The Basis Of Digital Basin

The foundation of hydrological forecast is data by field measure, such as hydrology datum, weather datum, terrain datum, geology datum and so on. If the data change, the result of hydrological forecast will change too. The influence of areal rainfall calculation and topographic characteristics in the basin on hydrological forecast is researched in the paper, and the theory foundation and the feasible technology project of the final digital hydrological model will be developed.In this paper, by use of the special analysis function of GIS, the drainage network was derived from DEM and the characteristics of the length and the gradient of the runoff flow routing were extracted. The validity of drainage network and the rule of terrain characteristics from different grid size DEMs are researched, and the quantitative basis is provided for the confirmation of hydrological model parameters. The result indicates that the validity of drainage network is related with the grid size of DEM and the earth's surface roughness, which is that accompanying with the increase of the earth's roughness, the DEM grid size of the validity of drainage network augments. The eigenvalue of terrain changes along with the increase of DEM grid size regularly so that the gist for practical application is supplied. Based on GIS, the correlation relationship between areal rainfall and the equality degree of precipitation station is found out, and the influence to hydrological forecast of two methods, the method of correlation relationship and the method of discrete data gridding, is analyzed and compared. The number of precipitation station without data and its position much impact on value of areal rainfall. It is The method of interrelationship that is applicable when the number of precipitation station without data is more and they form a bigger area, but not the one of discrete data meshing. However, two methods are both applicable when precipitation station without data is in the middle of stations with data. The correlation relationships between the topographic characteristics and the parameters of Xinanjiang model, such as SM, KI, KG, CS, CI, CG, X, were established. The above parameters are calculated according to correlation relationships and characteristic of basins with inverse deduction method.The results of simulation and validation in sub-basin show that the method is feasible to simulate hydrology process using the correlation relationships between the topographic characteristics and the parameters of runoff-producting and conflux. Using the correlation relationships, the resolution ratio of DEM that meet the requirement of flood forecasting is studied in different areas, which provides the foundation for actual application. The consequence demonstrates that DEMs of different grid size should be adopted according as the hypsography when model parameters are confirmed by the topographic characteristics. The simulation result can meet the demand of actual flood forecast when the grid size is less than 800 meter in mountainous area and 400 meter in hill area.