An Application Of Variable Infiltration Capacity (VIC) Macro Scale Land Surface Hydrological Model In China

This paper presents an application of variable infiltration capacity (VIC) macro-scale land surface hydrological model to simulate runoff for river basins in China. The entire land area of China is represented by 4355 cells with a spatial resolution of 50 X 50km2 for each cell. Most of the parameters needed by VIC are derived from geographic information, such as the 1:250 000 digital elevation model data, land use, vegetation and soil classification data. The VIC model combined with a new surface runoff parameterization, which takes into account the effects of soil heterogeneity on Horton and Dunne runoff, is applied to runoff simulation over the mainland area of China. The qualitative analysis shows that the spatial patterns of the simulated mean annual runoff and precipitation are consistent with each other. To test the modeling performance of the VIC model, streamflow simulation is conducted in catchments within Huaihe and Yellow River Basins, where a routing scheme with the unit hydrograph method for overland flow and the linear Saint-Venant method for channel flow is used to route the simulated daily runoff to the outlet of each catchment. Then, the simulated monthly runoff of VIC is compared to the monthly observed streamflow at the related gauge stations. Results show that the model can simulate the observationsaccurately.Generally, although most of parameters can be deduced from geographic information, some sensitive parameters in VIC have to be calibrated based on observed streamflow data. To calibrate model parameters where measured discharge data is unavailable, a methodology for model parameter transfer is introduced to transfer model parameters from data-rich areas to data-sparse areas. As a first attempt to transfer parameter, the land area in China is grouped by climate zones. The model parameters are calibrated for some catchments within zones, and then transferred to other catchments within the similar zones to validate the model performances. The transfer scheme can improve the simulation results as compared with the case of using uniform model parameters to data-sparse areas in previous work.In addition, the VIC model is coupled with the Providing Regional Climate for Impacts Studies (PRECIS) regional climate model to predict the effects of climate change on water resources in China. By using the results from PRECIS on reference years (1961-1990), A2 (2071-2079) scenario and B2 (2071-2090) scenario, which were developed in the IPCC Special Report on Emissions Scenarios (SRES), the VIC model is used to calculate the corresponding runoff changes in each province of ChinaIIin response to different climate scenarios. Results show that compared with the case in on reference years, mean annual runoff under A2 and B2 scenarios is predicted to be a decrease in the north and an increase in the south of China in spite of a rise in precipitation, which indicates more serious and frequent floods and drought in the future of China.