Snowmelt Runoff Simulation Based On VIC Model In Alpine Regions

Due to the special geographical location and terrain conditions of the alpine mountainous areas,the hydrological and meteorological monitoring sites are scarce,which result in a poor representation of measured data.To study the hydrologic regulation in scarce data area,increase the precision of snowmelt runoff simulation in alpine regions,and guide the work of snowmelt runoff simulation and other aspects in alpine region efficiently,Kashi river basin was chose to analyze the application of CFSR data(Climate Forecast System Reanalysis).Meanwhile,the correction methods were discussed in this place.The application effects of VIC(Variable Infiltration Capacity)model was analyzed in this area.After that,the responses of runoff in different climate scenarios were simulated by assuming climate scenarios.Through the identification of the time series components of the 10 th CFSR site and the Wulasitai station site,the periodic components and nonperiodic components of each precipitation time series are consistent with one another.However,there is a certain difference in the magnitude of the precipitation,which requires reasonable correction for using.The application of CFSR precipitation data that are obtained by three different precipitation correction methods is discussed based on the water balance mode of VIC model on the month time scale.Results show that the way,the correlation between the month precipitation of the nearest CFSR station and the month precipitation of the other CFSR station can be considered as the correction coefficient which used to correct the precipitation data of Wulasitai station for the CFSR station,is the best one for this study area.The runoff process and hydrological parameters of the Kashi River Basin were simulated by VIC model based on the CFSR precipitation data which was corrected.On the day time scale,the results of Nash coefficient and relative error in energy balance mode are 0.69,3.3% during the period of calibration and 0.72,5.9% during the period of verification.On the month time scale,0.86,3.3% during the period of calibration and 0.88,5.9% during the period of verification.On the day time scale,the results of Nash coefficient and relative error in water balance mode are 0.64,3.3% during the period of calibration and 0.70,13.1% during the period of verification.On the month time scale,0.80,4.7% during the period of calibration and 0.84,14.5% during the period of verification.The energy balance mode can better simulate the runoff process in the Kashi River Basin.In addition,the energy balance mode can also better simulate the spatial distribution characteristics of evaporation,snow sublimation,surface runoff,subsurface runoff and soil moisture of the first layer.Through the analysis of runoff at different time scales under different assumed climate scenarios,the temperature and precipitation have a significant effect on the runoff in the Kashi River Basin.The higher the temperature is dropped,the less the annual runoff curve is changed;the higher the temperature is raised,the more the annual runoff curve is changed.When the temperature is raised by-2? and 2?,the corresponding average runoff are increased by-2.97% and-2.34% respectively.When the temperature is raised by-1? and 1?,the corresponding average runoff are increased by-0.62 % and-0.69% respectively.There is a positive correlation between precipitation and runoff.When the precipitation is increased by-20% and 20%,the corresponding average runoff are increased by-30.57% and-31.39% respectively.When the precipitation is increased by-10% and 10%,the corresponding average runoff are increased by-15.41% and 15.63% respectively.It is found that when the precipitation is increased by 10%,the trends of runoff under the different scenarios are affected a little influence by temperature.The same as the situation that precipitation is decreased by 10%.Through the analysis of the average monthly flow process,it is found that the amount of runoff which corresponds to the high temperature is larger than the amount of runoff which corresponds to the low temperature during the period of rising water,and the phenomenon is contrary during the period of lowing water.