Simulation Of Snow Cover Process In Erqisi River Basin,Xinjiang

As an important part of the cryosphere,snow is extremely sensitive to climate change,which affects the security of regional water resources.Ertis river is the second largest river in Xinjiang and also an international river.Its water resources are of great significance to the social and economic development of Xinjiang,Mongolia,Kazakhstan and other countries.Accurate Snow Process Simulation Research on the basin scale can provide scientific means for the rational utilization of water resources in the basin,It can provide a reference for the simulation of snowmelt runoff and the study of hydrological process.Taking Xinjiang Erqisi River Basin as the study area,through the data recorded by kuwei meteorological snow frozen soil comprehensive observation station in the upper reaches of the basin,the single point simulation test is carried out by using FSM2(flexible snow model 2)and Noah-MP(Noah multiparametered)models,and the common statistical indexes are used,including correlation coefficient(R)The mean deviation(MD)and mean absolute error(RMSE)are used to evaluate the simulation results,and the model suitable for the simulation of watershed snow process is selected.Taking China Meteorological forcing dataset(CMFD)as the model driven data,the dynamic changes of snow depth and snow water equivalent in the whole irtsis River Basin are simulated,The simulated results are verified by the gridded data set of snow depth at Chinese meteorological stations in 1951-2015(GDSD)developed by the National Meteorological Administration,and the snow depth retrieved based on sentinel-1a is used to verify the snow depth simulated in typical areas.The main conclusions of this study are as follows:(1)The single point scale simulation test of kuwei observation station shows that based on the FSM2 model,when the temperature of 0 ? is taken as the threshold for dividing rainfall and snowfall(scheme 1),the R between the simulated snow depth and the observation data is 0.42,MD is 2.86,RMSE is 13.68,and the R between the simulated snow water equivalent and the observation data is 0.24,MD is 4.06 mm,RMSE is 25.04;When the function between snowfall proportion and temperature is taken as the standard for dividing rainfall and snowfall(scheme 2),the R between snow depth and observation data based on FSM2 simulation is 0.64,MD is 2.42,RMSE is 11.34,and the R between snow water equivalent simulation result and observation value is 0.36,MD is 3.77,RMSE is 22.18.The effect of snow depth based on FSM2 simulation is significantly better than that of snow water equivalent.Based on Noah-MP model,the R between simulated snow depth results and observed values is 0.82,MD is 5.51,RMSE is 10.25,and the R between simulated snow water equivalent results and observed values is 0.88,MD is 6.21,RMSE is 9.84.From this result,the accuracy of snow depth and snow water equivalent simulated by Noah-MP model at kuwei station is obviously better than that of FSM2 model.(2)Taking the high-resolution CMFD data as the Noah-MP model driving data,the snow depth and snow water equivalent data of Ertix River Basin from 2010 to 2014 are simulated.The verification results show that the daily average snow depth series of Ertix River Basin simulated in this study is in good agreement with GDSD data,and the values of R,MD and RMSE are respectively 0.72 ? 5.51 ? 10.26.The accuracy of snow depth simulated in this study is also compared with CSS.The results show that the CSS snow depth is in good agreement with GDSD and the snow depth simulated in this study in 2011-2012 and 2013-2014,However,CSS data is significantly underestimated in 2010,2012-2013 years with high snow depth.(3)Based on the simulation results of this study,the spatial distribution of snow depth and snow water equivalent in Erqisi river basin is high in north area and low in south area.Based on the data from 2010 to 2014,the annual average snow depth of Erqisi river basin is 42.20 cm,and the maximum snow depth is 84 cm,which appeared in February 2010;The annual average snow water equivalent is 120.40 mm,and the maximum snow water equivalent is 245 mm,which is consistent with the snow depth.(4)In the kayertes River Basin in the upper reaches of the Ertix River Basin,the snow depth from September 2017 to April 2018 is retrieved by sentinel-1a,and the retrieved snow depth is verified based on the snow depth synchronously observed by kuwei station.The results show that the snow depth retrieved by sentinel-1a is in good agreement with the observation data and can reflect the temporal variation characteristics of snow in the basin.The snow depth simulated by Noah-MP is verified based on the snow depth time series retrieved by sentinel-1a.The results show that the average snow depth of kayaltes River Basin obtained by inversion is0.62-14.20 cm,and the average snow depth obtained by Noah-MP simulation is 0.42-15.80 cm,The snow depth retrieved by sentinel-1a is in good agreement with the snow depth simulated by Noah-MP in the kayaltes River Basin.