Variation Characteristics Of Lakes On The Hoh Xil Under Climate Change

Tibet Plateau(TP)is the“third pole”of the earth,the“driver”and“amplifier”of global climate change.Under global climate change,the water cycle of TP has changed.The temperature rises and the precipitation increases,causing the glacial and permafrost melting and a large number of lakes expanding dramatically.The Zhuonai Lake-Salt Lake(ZS)Basin,in the HohXil,is also located in the closed basin of TP.After 2010,the Salt Lake expend rapidly,at risk of spillover.Once happened,affecting the surrounding permafrost,it will damage the Qinghai-Tibet Railway and the highway.It will also connect the Qingshui River and then flow into the Yangtze River.The high salinity of the lake water will affect the upper reaches of the Yangtze River.Monitoring the dynamic changes of lakes in the region and further analyzing the lake's response to climate change,not only to promote the study of the water cycle in TP,but also for the safety of the Qinghai-Tibet Railway and Highway and the natural ecological environment protection in the upper reaches of the Yangtze River.In order to study the impact of climate change on lakes,and solve the problem of salt lake floods,this study analyzes the 30-year variation characteristics of the four main lakes in the ZS Basin and the response of the total area change to the climate,combined with the monitoring data and meteorological data.According to the sounding data and DEM,the water level-area-volume curve is established.The variation characteristics of Salt Lake in recent years are analyzed.The response model of Salt Lake to meteorological factors is established.The spillover time of Salt Lake is predicted,which provides a decision for solving Salt Lake floods.The results are as follows:(1)Since the end of the 1990s,the temperature has increased,the precipitation has increased,and the regional climate has changed to warm and humid.Under the influence of climate change,the total area of Zhuonai Lake,Kusai Lake,Haiding Noor Lake and Salt Lake experienced a process of decrease and increase.The total area of lake decreased by 35.62km~2 from 1989 to 1995,and 1996-2004,the total area of lakes fluctuated around 600km~2,and the total area increased by nearly 150km~2 in 2004-2018.The lake area accelerated in 2015-2018,with an average growth rate of 13.96km~2/a.The total area of the four lakes is highly positively correlated with precipitation and temperature changes,and has a strong negative correlation with changes in wind speed,and has no correlation with changes in sunshine duration.(2)Before the Zhuonai Lake collapsed,the area of the four Lakes changed in unison and experienced a process of reduction and enlargement;after the Zhuonai Lake collapsed,the area of the Four Lakes changed greatly in 2011,and the lakes were basically stable after 2012.The Salt Lake increased rapidly at a rate of 18.90km~2/a after2015.The main changes in the orientation of the lake remain basically unchanged,and the cancroids are all shifted to the east,revealing the trend of water resources transfer in the plateau.(3)The level-area-volume relationship curve was established,and the level and volume change process of the Salt Lake in 2015-2018 was obtained.The water volume rapidly increased after 2015.The change of water quantity has significant correlation with the four meteorological factors,the correlation with precipitation is the largest,and the correlation with temperature is small.A stepwise linear regression was used to establish a water volume response model.Under adverse conditions,the Salt Lake will overflow in August 2019.