Applicability Analysis Of Simulation Of Snowmelt Runoff In The Lhasa River Basin Based On SRM Model

This article is completed under the patronizing of Sichuan key laboratory open project(Project number: PAEKL-2015-Y1).The paper is based on the SRM(Snow Runoff Model)to do research on snowmelt runoff simulation in the Lhasa river basin on a daily time scale and a spatial scale of hydrological site,by using multi-source data,such as MODIS snow cover products,SRTM DEM data,GLDAS(Global Land Data Assimilation System)model data,TRMM(Tropical Rainfall Measuring Mission)precipitation product,hydrological station measured runoff data and so on.And this study also aims at verifying the overall applicability of the SRM model to the whole Lhasa river basin.Summarizes the primary coverage which this article studies as follows to show:(1)Using the MODIS snow cover products,analyzes the variations on snow cover in time and spatial scales,further obtains the typical years of snow cover's characteristic in the Lhasa river basin.(2)According to the snow cover typical years and the available measured runoff data in this paper,sets the target year for snowmelt runoff simulation.And considering synthetically the daily snow cover,temperature,measured runoff data and other factors,identifies the period of snowmelt runoff simulation in a year.(3)Using the GLDAS-2 data,TRMM precipitation product,measured runoff data and other multi-source data,obtains the temperature,precipitation,regression coefficient and other SRM parameters.And based on the basic formula of the SRM model,does research on the simulation of snowmelt runoff in the Lhasa river basin at the hydrological site scale.Analyzing the results represents that:(1)The snow cover rate and snow cover days have significant differences on the time and spatial,the spatial variation increases with the rises of elevation,and the typical years of snow cover's characteristic in the Lhasa river basin from 2000 to 2017 are2000,2001,2002,2003,2008,2016,2017.(2)Simulates initially by using the SRM parameters in 2008 at Lhasa station,calibrates the part uncertain parameters by using data in 2000 and 2001 at Lhasa Station and verifies the accuracy of the calibrated SRM model in 2008 at Pangduo station,Tangjia station,Yangbajing station independently.And determines that the snowmelt period in the Lhasa river basin is from May to October in a year.(3)Verifying the independent accuracy of the calibrated SRM model respectively at the Pangduo station,Tangjia station and Yangbajing station from May to October in 2008 by using the parameters at Lhasa station in 2000 and 2001,the results shows that the NSE of Tangjia station is the highest in the three stations,which is over 0.6,and the NSE of Yangbajing station is the lowest,which is lower than-70,and the NSE of Pangduo station is negative,which is close to 0.Analyzing comparatively with the combination of the topography,landform,meteorological factor,snow cover characteristics at the four hydrological stations,the overall characteristics of Tangjia station are the closest to Lhasa station,and the difference between Yangbajing station and Lhasa station is the largest,so the simulation accuracy of Tangjia station is the highest.Therefore,the SRM model is suitable for Tangjia station,not for the Pangduo station and Yangbajing station,especially totally not inadequate for the Yangbajing station,which means the SRM model is only suitable for snowmelt runoff simulation of a single station in the Lhasa river basin.