| Glaciers are one of the most climate-sensitive components of the global natural water towers.Under the climate conditions of continuous global warming,most glaciers in the world are facing severe melting,which will affect the supply of water resources in the region.And will also cause natural disasters such as glacier surging,ice collapse,and glacier debris flow,threatening the safety of human production and life.As the core of glacier evolution and development,the study of glacier movement is conducive to understanding glacier mass and energy redistribution,and helps to predict and prevent glacier disasters related to abnormal glacier movement.There are a lot of glaciers in Tuanjie Peak,the highest peak of the Qilian Mountain.In recent years,scholars have found that some glaciers in this area have terminal advance.However,how do the glaciers change in Tuanjie Peak,whether the advance of some glaciers is affected by glacier surging,and how glacial movement affects the changes of glaciers in the region need to be further revealed.Therefore,in this study,glacier length/area information in 6 periods of 1966,1990,2000,2006,2015 and 2020 was obtained based on multi-period high-resolution remote sensing images and glacier inventory data.Based on the multi-source digital elevation model（DEM）and the glacier surface elevation change dataset,five periods of ice surface elevation changes from 1966-2000,2000-2005,2005-2010,2010-2015 and 2015-2020 were obtained.Based on Sentinel-1,Landsat images and glacier surface velocity datasets,the interannual velocity of glacier surface from 1986 to 2021 and the～24-day interval between 2014.10 and 2022.4were obtained.According to the above information,the surge glaciers in the Tuanjie Peak were identified;Based on the mass balance model and combined with the characteristics of temperature and precipitation changes,the seasonal scale mass balance and glacial meltwater from 1990 to 2017 were reconstructed.Based on the above results,the causes of glacier change,as well as the seasonal variation characteristics and control factors of glacier surface velocity were comprehensively discussed.The main conclusions are as follows:（1）In 2020,there are 91 glaciers in Tuanjie Peak,covering an area of 134.40±4.77km2.Compared with 1966,the number of glaciers in Tuanjie Peak decreased by 11 in2020,and the area decreased by 28.31±5.67 km2,accounting for 17.40±3.48%of the total area in 1966,with an annual shrinking rate of 0.32±0.06%.From 1966 to 2020,the average thinning rate of glaciers in Tuanjie Peak was 17.26±3.57 m,the average annual thinning rate was 0.32±0.07 m,the mass balance was-0.27±0.06 m w.e.a-1,and the ice loss was about 2.67±0.33 Gt.（2）The glacier surface velocity in Tuanjie Peak is relatively low,with an average velocity of 4.85 m a-1.During 1986-2018,nearly 96%of the glaciers’average surface velocity was below 9 m a-1,and the glacier velocity showed a slowing trend during the study period.From 1990 to 2017,the annual runoff depth of glacial meltwater was 0.57m,the total amount of meltwater was 221×105 m3,and the annual amount of meltwater was 7.9×105 m3.The total amount of glacial meltwater showed an increasing trend before 2010,and a slight decreasing trend after reaching the peak in 2010.In 2010,the runoff depth of meltwater was about 1 m,and the total amount of meltwater was13.7×105 m3.After 2010,the meltwater showed a slight decreasing trend.（3）According to the variation information of glacier length,surface elevation and movement velocity,we found that 7 glaciers in Tuanjie Peak had typical characteristics of surge glaciers,and they were divided into 5 confirmed surge-type glaciers and 2possible surge-type glaciers.The terminal advance and thickening of the ablation area of the intra-regional glacier are not obvious,which may be due to the smaller scale of the glacier compare with other regions of the High Mountain Asia,the slower movement speed and smaller energy of the glacier during the transition period,and the mass transported from the accumulation area to the receiving area rapidly melts under the influence of climate,which is not enough to produce obvious transition characteristics.（4）Through the analysis of glacier mass balance,it is found that the accumulation of glacier mass caused by increasing precipitation is not enough to make up for the mass loss caused by rising temperature,which is the main reason for the glacier shrinkage in Tuanjie Peak.The change of glacial meltwater may be the influencing factor of the difference of glacial seasonal velocity in the region.Changes in glacial meltwater will lead to changes in basement water pressure and subglacial hydrological system:At the beginning of the ablation season,temperature rises and precipitation increases,resulting in increased glacier ablation.At the same time,the subglacial hydrological system is underdeveloped,and glacial meltwater penetrates into the basement,leading to accelerated glacier movement.In the accumulation season,the temperature is low,the precipitation is less,there is no obvious melting of the glacier,the basement water pressure is basically stable,and the movement speed is relatively stable and slow. |
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