Simulation Of Snowmelt Runoff In Cold And Arid Areas And Uncertainty Analysis

The climatic characteristics such as low precipitation and large evaporation in the cold and arid regions make water resources one of the important factors restricting local social and economic development.The cold and arid regions of China are mainly distributed in the inland areas of northwest China.The negative temperature conditions at higher altitudes make the precipitation to occur in the form of snowfall and a large number of glaciers are developed in these regions,thus the water resources are relatively abundant.Melting ice and snow is the main source of domestic,industrial and agricultural water use in rivers and downstream areas in such regions.The cold and arid regions with melting snow runoff as the main water resources are very fragile and extremely sensitive to climate change.Through the study of ice-melting and snow-melting runoff in cold and arid areas,it is of great significance to deeply understand the runoff formation mechanism,change characteristics and influencing factors of the river basin,and improve the ability of runoff forecasting,scientific management and utilization of local water resources.In view of the uncertainty analysis of snowmelt runoff simulation and the relevant basic data of hydrology and meteorology in the Tizinafu river basin in southwestern Xinjiang,the following studies are carried out by using the lumped hydrological model SRM and the semi-distributed hydrological model TOPMODEL,respectively.(1)By studying the snowmelt runoff model of SRM in the study area,the applicability of four baseflow separation methods was evaluated.On the basis of therunoff calculation of SRM model,adding baseflow data can improve the runoff simulation ability of SRM model in dry seasons.Four models of SRM(SRMB-C?SRMK?SRMBFI and SRMH)were established by combining four baseflow separation methods(digital filtering method,Kalinin method,BFI method and HYSEP method).MCMC method which based on DREAMzs algorithm is used to analyze the uncertainty of model parameters.The results show that SRMK based on Kalinin separation method is the best,and the Kalinin method is the most suitable baseflow separation method of the study area.(2)By using different temperature data as SRM input variables,the applicability of the three kinds of temperature data was evaluated.These data(temperature lapse rate interpolation data,VIC temperature dataset and MODIS remote sensing temperature data)were input respectively to drive SRM,and three comparison models(SRMK,SRMvic,SRMM)were established.The parameter uncertainty analyzed by MCMC method based on DREAMzs algorithm was carried out.The analysis and comparison results show that the temperature lapse rate interpolation data and VIC temperature dataset can better drive SRM model,and the simulation results of SRMM which used MODIS remote sensing data are poor.(3)Evaluating the performance of different hydrological models in snowmelt runoff simulation in the study area.The TOPMODEL model was established based on DEM data and the topographic index is calculated by the geometric conical tangent circle method,then the process of runoff generation and confluence is calculated with the topographic index.The key parameters of the model are identified by the MCMC method to obtain the optimal parameter group.In accordance with the comparison of runoff simulation results of SRM and TOPMODEL,it is concluded that the lumped hydrological model is better than the semi-distributed hydrological model in the cold and arid mountainous areas where there is few representative observation data(such as temperature and precipitation).