Effects And Simulation Of Glacial Hydrological Processes In The Dongkemadi River Basin At The Source Of The Yangtze River

In the context of global warming,glaciers,as indicators of climate change,are extremely sensitive to climate change.This paper attempts to establish the relationship among meteorology,glacier material balance,glacier meltwater runoff,and river runoff in the Dongkemadi River Basin,so as to obtain the change trend between glacier material balance and glacier meltwater runoff in the research area under the background of climate warming,so as to provide scientific basis for the evaluation of water resources in the basin.The main purpose of this paper is to simulate the change trend of glacier material balance and the proportion of glacier meltwater contributing to river runoff in the Dongkemadi River Basin of the representative Yangtze River source basin in the past 50 years through the HydroGeo Sphere(HGS)hydrological model and simulate the change trend of glacier elements under six different meteorological conditions in the next 100 years through the water balance principle.Firstly,the formula between the meteorological data of the research area and the meteorological data of the four surrounding meteorological stations(Anduo,Naqu,Tuotuo River and Wudaoliang)was fitted.The temperature and precipitation data of the research area from 1966 to 2015 were reconstructed by using this formula and the meteorological data of the four meteorological stations.Secondly,the hydrological model of the basin HGS was constructed by using geological data(lithological distribution),elevation data,glacier distribution data(remote sensing satellite)and hydrological data in the study area.The model was used to simulate the glacier material balance and the proportion of glacier melt water in the study area from 1966 to 2015.The formula derived from the thickness of the Dongkemadi glacier is used to simulate the thickness of the Dongkemadi glacier.The trend of runoff depth in the basin in the next 100 years was predicted by inputting glacial melt and precipitation into the HGS model under different climatic conditions.The results show that:(1)From 1966 to 2015,the annual average temperature increased by 0.38?/10a,the annual precipitation increased by 16.4 mm/10a,and the annual positive accumulated temperature increased by 35?/10a.(2)The NSE efficiency coefficient of the daily runoff depth is above 0.65,the NSE coefficient of the monthly runoff depth is 0.96,and the annual runoff depth error is within 11%.The R2 of runoff depth and temperature and precipitation are 0.63 and 0.004,respectively.(3)Between 1966 and 2015,the average glacier mass balance was-151 mm,and the cumulative material level was-7.55 m;precipitation,positive accumulated temperature,glacial meltwater runoff depth and glacier material balance R2 are 0.50,0.51,0.41,respectively.The increase in runoff depth in the basin is 4.29 mm/a,and the glacial meltwater contribution in the increase in runoff depth is 68%.(4)In the next 100 years,when the temperature rises by 1?,2?,and 3?,the length of the main line of the Dadong glacier is reduced by 56 m,392 m,and 2451 m,respectively;the length of the Xiaodong glacier is reduced by 150 m and 2713 m,3255 m respectively.The trend of annual runoff depth is:the temperature rises by 1?,and the annual runoff depth shows an increasing trend and when the temperature rises by 2? and 3?,the annual runoff depth increases first and then decreases.