NUMERICAL SIMULATION EXPERIMENTS BY NESTING HYDROLOGY MODEL DHSVM WITH REGIONAL CLIMATE MODEL RegCM2/CHINA

Based on improvement of a distributed hydrology-soil-vegetation model (DHSVM for short) and its application to North China,a nested regional climatic-hydrologic model system is developed by connecting DHSVM with RegCM2/China.The simulated climate scenarios,including control and 2×CO2 outputs,are downscaled to 8 stations in Luanhe River and Sanggan River Basins to drive the hydrology model.According to simulation results,under double CO2 scenarios,annual mean temperature and evapotranspiration will increase 2.8℃ and 29 mm,respectively;precipitation also increase but with different value for each basin,6 mm for Luanhe River Basin while 46mm for Sanggan River Basin;runoff change for the two basins is different too,27mm decrease for Luanhe River Basin while 26 mm increase for Sanggan River Basin.As a result,the runoff in future for Luanhe River Basin and Sanggan River Basin will be 74 mm and 71mm,respectively,which is approximately a quarter of annual mean runoff(284 mm)of the whole country.Total streamflow for the two basins will decrease about 2.5×108m3.All these indicate that the warm and dry trend will continue in the two river basins under double CO2 scenarios.The nested model system,with both climatic and hydrologic prediction ability,could also be applied to other basins in China by parameter adjustment.