1993—2016年喀喇昆仑山中部Shigar流域冰川物质平衡变化空间特征研究

Spatial characteristics of glacier mass balance variations in Shigar basin of the central Karakoram Mountains,1993—2016

基于Landsat系列卫星遥感影像、SRTM DEM和TanDEM-X DEM对喀喇昆仑山中部Shigar流域不同类型冰川的面积变化、物质平衡进行了分析。结果表明:1993—2016年间Shigar流域内有25条跃动冰川(面积增加1.30km2),68条前进冰川(面积增加0.86km2),50条退缩冰川(面积减少3.48km2),376条稳定冰川(面积减少1.34km2)。跃动冰川的冰川长度和规模均集中在较大范围内,前进冰川的规模略高于退缩冰川,退缩冰川多为小规模冰川,特大规模冰川保持稳定状态;不同类型冰川的空间分布差异较大,且不同海拔带内水热组合条件不一致也影响冰川运动状态。2000—2013年间,流域内跃动冰川物质平衡为(+0.17±0.03)m w.e.·a^(-1),前进冰川物质平衡为(-0.01±0.03)m w.e.·a^(-1),退缩冰川物质平衡为(-0.22±0.03)m w.e.·a^(-1),稳定冰川物质平衡为(-0.01±0.03)m w.e.·a^(-1)。四类冰川表面高程变化随归一化冰川长度的变化模式以及不同海拔带内和不同坡度区间的冰川表面高程变化显示:跃动冰川主要特征是积累区物质积累量大;前进冰川上部物质积累并且向下运动推动冰川末端前进;退缩冰川消融区物质亏损量大使得冰川末端退缩。

Glacier area changes in Shigar basin between 1993 and 2016 were derived from Landsat data.Glacier mass changes were determined using geodetic methods based on digital elevation models(DEMs)derived from SRTM DEM(2000)and TanDEM-X DEM(2013).Results showed that Shigar basin has 25 surge-type glaciers(area changed by+1.30 km2),68 advancing glaciers(area changed by+0.86 km2),50 retreating glaciers(area changed by-3.48 km2),and376 stable glaciers(area changed by-1.34 km2)from 1993 to 2016.The length and size of surge-type glaciers were concentrated in a large range,the size of advancing glaciers were larger than retreating glaciers which were mostly small size,while the four largest glaciers in basin remained stable.The spatial distribution of different glacier types were different,and the different combination of precipitation and temperature in different elevation made the states of glacier motion are diverse.Surge-type glaciers gained mass at a rate of(+0.17±0.03)m w.e.·a^(-1)during 2000 to 2013,while advancing glaciers lost mass at a rate of(-0.01±0.03)m w.e.·a^(-1),retreating glaciers lost mass at a rate of(-0.22±0.03)m w.e.·a^(-1)of and stable glaciers lost mass at a rate of(-0.01±0.03)m w.e.·a^(-1).Meanwhile,the elevation changes of surge-type,advancing,retreating,and stable glaciers in different altitudes and slopes and the trends of glacier elevation change along with the normalized glacier length show that surge-type glaciers had a big material accumulation;the material on upper part of the advancing glacier accumulated and moved downward to push the glacier terminal forward;the mass lost in the ablation area of retreating glaciers led to the glacier terminal receding.