Changes Of Mountain Glaciers And Their Response To Climate In Xinjiang Section Of The Silk Road Economic Belt

The Xinjiang section of the Silk Road Economic Belt is an important traffic artery of the Green Silk Road.Glaciers in the region are the main fresh water resources for economic development and agricultural construction,which is of great significance for maintaining the ecological balance and sustainable social and economic development of the region.In the context of global warming,understanding the glacier changes in Xinjiang section of the Silk Road Economic Belt can help to understand regional water resources reserves and changes,and is also a major demand of regional water resources management and planning departments.In the past,there were few researches on the large-scale and long time series of glacier changes along the Xinjiang section of the Silk Road.Therefore,using topographic map,SRTM C-DEM,ASTER stereo image pair,Tan DEM-X and Landsat ETM/OLI multi-source data,this paper analyzes the variation characteristics of glacier area,surface elevation and reserves in Xinjiang region of the Silk Road Economic Belt during 1965-2020,and discusses the response to climate change.The main conclusions are as follows:（1）During 1965-2020,the glaciers in Xinjiang section of the Silk Road were in a state of retreat as a whole,and the glacier area decreased by 1950.22 km²,with a total retreat ratio of20.4%and an average annual retreat rate of 0.37%.The number of glaciers dropped from 8,772in 1965 to 8,283 in 2020.The glaciers in the Xinjiang section are mainly distributed in the altitude range of 3000-6200m,and the distribution area of glaciers in each altitude zone first increases and then decreases with the increase of altitude.In recent 55 years,the retreat of glaciers in the Xinjiang section has shown a trend of first increasing and then decreasing with the increase of altitude.The glaciers in north and south Tien Shan Mountains retreated,and the retreat rate of glaciers in north Tien Shan Mountains was higher than that in South Tien Shan Mountains.From the perspective of different regions,glaciers in each region showed different degrees of retreat,and the spatial difference of glacier area retreat rate showed the trend of west Tien Shan North Road>East Tien Shan North Road>middle Tien Shan North Road>west Tien Shan South Road>East Tien Shan South Road.From the perspective of slope,the spatial difference of glacier area distribution on the north slope is larger than that on the south slope.From 1965 to 2020,glaciers in Xinjiang section showed a trend of area retreat on all slopes,and the extent of retreat was different.（2）The glaciers in Xinjiang section of the Silk Road Economic Belt showed a thinning trend during 1965-2020.The decrease rate of glacier surface elevation was 0.38±0.18 m a^-1,and the glacier ablation accelerated after 2000.Among them,the glacier surface elevation reduction rate is-0.31±0.15m a^-1during 1965-2000,and-0.49±0.26m a^-1during 2000-2020.In recent 55years,glaciers in the northern and southern sections of the Tien Shan Mountains have been melting and thinning continuously,and the rate of surface elevation decline in the northern section is higher than that in the southern section,with a spatial difference of the west section>the east section in each period.The spatial variation of surface elevation from 1965 to 2020shows a trend of west Tien Shan North Road>east Tien Shan South Road>west Tien Shan South Road>East Tien Shan North Road.The descending rate of glacier surface in Xinjiang is higher in the south and lower in the north,and higher in the west and lower in the east.There is a significant linear correlation between the change rate of glacier elevation and the elevation,which shows that the change rate of glacier elevation decreases with the elevation increasing at100m altitude.The most significant decrease of glacier surface elevation is located in front of the ablation area.From the aspect of slope,the surface elevation of glaciers in each slope direction showed a downward trend from 1965 to 2020,and the rate of decline was different in each slope direction,and the decrease of glacier surface elevation was more obvious after 2000.（3）The material loss of the glaciers in Xinjiang section of the Silk Road Economic Belt was obvious in the past 55 years,and the average material loss rate was-0.32±0.15m w.e.a^-1during1965-2020.The glacier mass loss rate was-0.26±0.11 m w.e.a^-1during 1965-2000.The mass loss rate was 0.42±0.22 m w.e.a^-1during 2000-2020.The north and south Tien Shan Mountains were in a state of material loss from 1965 to 2020,and both showed an accelerated trend of glacier material loss after 2000.From 1965 to 2020,the spatial difference of the average glacier mass loss rate of the glaciers in Xinjiang section was as follows:North Tien Shan Road>South Tien Shan Road.In addition,the spatial variation of glacier mass loss was more in the western section than in the eastern section.The material loss of glaciers in the Xinjiang section is high in the north and low in the south,and high in the east and low in the west.In the past 55 years,glacier mass loss in each region showed the trend of west North section>west South Tien Shan section>East North Tien Shan section>East South Tien Shan section.（4）The observation results of meteorological stations in Xinjiang section of the Silk Road Economic Belt show that the temperature and precipitation in this region have both shown an increasing trend in the past 55 years,which are 0.36℃/10a and 8.42 mm/10a,respectively.The influence of temperature and precipitation on the thinning of glaciers in Xinjiang is stronger than other meteorological parameters.Increasing temperature will aggravate the loss of glacier material,and increasing precipitation is conducive to the accumulation of glacier material.During 1965-2000,the annual mean temperature increased significantly,while the annual mean precipitation increased weakly.As the glaciers in Xinjiang continue to melt and thin,the loss of glacier material caused by warming temperature is far greater than the accumulation caused by precipitation.Therefore,we conclude that the major cause of the loss of glacier reserves along the Xinjiang section of the Silk Road is the significant rise in temperature.