Glacier Changes In Northern Tibetan Plateau's Endorheic Basin And Its Contribution To Lake Changes

In recent years,under the background of the rapid warming of the Tibetan Plateau,the glaciers and lakes in the endorheic Northern Tibetan Plateau are showing an accelerating trend of change,which has brought several potential risks to the ecological environment and production safety of the Tibetan Plateau and surroundings.Although some studies have quantitatively analyzed the main influencing factors of lake water balance for single or several lakes,the glacier changes and it is contribution to lake changes at lake-basin scale across the entir Northern Tibetan Plateau remains poorly quantified.Hence,In this study,we analyzed the spatial and temporal characteristics of glacier area and glacier surface elevation changes in the endorheic Tibetan Plateau during 2000-2016,and qualitatively discussed the correlation between glacier changes and temperature and precipitation.In this study,we analyzed the spatial and temporal characteristics of glacier area and glacier surface elevation changes in the endorheic Tibetan Plateau during 2000-2016,and qualitatively discussed the correlation between glacier changes and temperature and precipitation.Combined with the later-water mass in the Inner-TP,the ratio of excess glacier meltwater runoff to lake volume increase was estimated.The main conclusions are shown as following:(1)Landsat 104 OLI/ETM+/TM images were used to extract the glacier boundaries in 2000and 2016 by manual delineation method,and the glacier area distribution and change characteristics were analyzed.In 2016,there were 7132 glaciers covering an area of 7176.47km² in the endorheic Tibetan Plateau.From 2000 to 2016,the glacier area in the endorheic Tibetan Plateau decreased by 185.65 km²,the area shrinkage rate is 2.52%.The glacier change rate decreased with the increase of latitude,and the glacier shrinkage in the West Kunlun and Karakoram Mountains was the weakest.The distribution and change characteristics of glaciers have certain regularity in terms of glacier area class,aspect,elevation and other attributes.In addition,there were 12 advanced glaciers,mainly in the central and northern regions,and 38 disappeared glaciers,concentrated in the southern margin.(2)Based on SRTM and TANDEM data,surface elevation changes of glaciers in the endorheic Tibetan Plateau between 2000 and 2013 were calculated by geodetic method.The estimated mass budgets of 16 selected glacier area in the endorheic Tibetan Plateau showed that the change rate of surface elevation range were-0.54±0.24?0.09±0.05 m a^-1,and it decreases from north to south.Different from other regions,the West Kunlun and surroundings showed an positived mass balance.Between 2000 and 2013,a average change rate of glacier surface elevation of-0.12±0.11 m a^-1 was estimated for the entire endorheic Tibetan Plateau.There was a high correlation between the glacier mass change and the temperature change trend in the endorheic Tibetan Plateau,while the influence of the precipitation change on the glacier mass change is weak.(3)From 2000 to 2016,the glacier area in the endorheic Tibetan Plateau increased by 6240.70km²,the area increase rate is 21.67%.The area of glacier-fed lakes expanded by 4267.20 km²,with an area increase rate of 14.82%,and that of non-glacier-fed lakes expanded by 1973.5km²,with an area increase rate of 35.63%.From the perspective of area increase,the area increase of glacier-fed lakes is twice as much as that of non-glacier-fed lakes,but the area increase rate of non-glacier-fed lakes is significantly higher than that of glacier-fed lakes.(4)Combined with the data of lake water level published in previous studies,the average contribution rate of glacier mass loss to lake water volume in 40 basins in the endorheic Northern Tibetan Plateau was calculated as 17.24%.In the 23 basins where ice volume decreased and lake volume increased,the contribution rate ranged from 1%to 50%,with an average contribution rate of 14.12%.It can be concluded from the estimation results that the continuous loss of glacier mass in the endorheic basin promotes the expansion of the lake in recent years,but is not the main driving force for the increase of lake water volume.