Application Research On VIC Model In Chinese Humid Areas

At present, with the development of GIS, Remote System, and computer technology, the distributed hydrological model has quickly developed. It can impersonally reflect the effect that the dimensional distribution factors of the climatic and land surface have on the form of rainfall-runoff. And it provides an effective tool to simulate the physical process of rainfall-runoff. Its parameters have unambiguous physical meaning. The model has solved the problem of the parameters: pertinency and indefinity. Therefore it can be well applied in the ungauged basins.This paper reviews the internal and overseas development of the distributed hydrological model and that of a distributed conceptual hydrological model, named VIC (Variable Infiltration Capacity) model. And, VIC is selected to study the soil parameters in Chinese humid basins. Firstly we study the development of the VIC model, especially the development of the parameters, and then combined the model theory to analyse the compute procedure. Eight representative basins in Chinese humid area such as Waizhou were selected for the modeling experimentation. The basins were divided by 50km × 50km grid. The results prove that the VIC model is good applied in Chinese humid basins. Through the experimentation, seven soil parameters of VIC model have been calibrated, which are the variable infiltration curve parameter (B), three parameters about baseflow(Ds, Dsmax, Ws) and depth parameters of three soil layers (d1, d2, d3). In addition, the other parameters used in the model have been demarcated in this study.Based on the modeling experimentation, this study uses sensitivity method to calculates the sensitivity of the seven soil parameters to the relative error of runoff (the relative error between the simulation and measure runoff) and the efficiency coefficient (the inosculating degree between the simulation and measure data), using the sensitivity theory. And analyze the sensitivity of the seven soil parameters to the simulation results. The results indicate that the depth of the second soil layer is more sensitive to the relative error of runoff than the other parameters. And the variable infiltration curve parameter is more sensitive to the efficiency coefficient than the other parameters.After analyzing the sensitivity of the seven soil parameters, this study produces the "average parameter" as the first blue print, the average of the rating parameters of the eight basins in this study, to transplant parameters in the ungauged basins. Based on the distribution compartmentation of climate, soil, vegetation in Chinese humid areas, this study produces the sub-area method as the second blue print to transplant parameters. And the two methods are applied in Chinese humid areas. The results indicate that the two methods are feasible. Finally, the two methods are contrasted and analysysed.This paper gave some primary discussion on the parameter regionalizing in Chinese humid areas based on the research of the soil parameters of the VIC model.