中国喜马拉雅山地区冰川1999—2015年期间动态变化遥感调查

根据完成的青藏地区基于1999年ETM、2014/2015年GF-1/OLI两期遥感调查的冰川编目数据,对1999—2015年期间中国喜马拉雅山地区的冰川变化进行分析。结果显示,从1999—2015年间,中国喜马拉雅山地区的冰川普遍退缩,冰川数量减少了85条,面积减少了42.00 km²,冰储量减少了2.385 km³ ,分别占其减少变化率的1.53%、0.67%和0.50%。沿山脉由东向西冰川变化不一,其中东段的冰川数量减少多,西段的冰川面积和冰储量减少多,并且东段的数量减少变化率远大于西段,西段的面积、冰储量减少变化率大于东段,中段的冰川相对稳定。喜马拉雅山地区的冰川在北、北东和东等方向上发生退缩,且减少量依次减少,其中东向的数量减少变化率最大,北东向的面积减少变化率最大,而北向的减少变化率最小。冰川在不同坡度退缩程度不一,在坡度10°~15°范围冰川面积退缩最多、变化率最大,在坡度30°~35°范围数量减少最多、变化率最大。冰川在高程5 500~6 000 m区间数量和面积退缩量最多,其次是在高程5 000~5 500 m区间;在高程3 500~4 000 m区间的退缩变化率最大,而在高程6 000~6 500 m区间的退缩变化率最小。不同流域中冰川变化差异较大,在雅鲁藏布江流域(5O2)冰川数量和面积减少最多,其次是朗钦藏布等流域(5Q2)和朋曲等流域(5O1),而扎日南木措流域(5Z3)的冰川减少量最小,但是变化率最大。总之,小冰川的大规模退缩或者消失,较大冰川也普遍退缩,是喜马拉雅山地区冰川变化的特点。喜马拉雅山地区冰川退缩与气候变化关系密切。根据多年年平均气温和年降水量分析,自1961年以来,该地区年平均气温显著上升,年降水量有增有减,但气温上升、降水量减少是导致冰川消融原因之一。

Remote Sensing Survey on Glacial Dynamic Evolution in the Himalayas in China During 1999—2015

Using the two-phase remote sensing images based on the ETM in 1999 and the GF-1/OLI in 2014/2015 in the Qinghai-Tibet region, the glacial cataloging is completed and the glacial changes in the Chinese Himalayas during 1999-2015 is summarized. The results show that glaciers were generally retreating in the Himalayas from 1999 to 2015. There were 85 (1.53% of total)retreating glaciers with a total decrease in size and volume of 42.00 km²(0.67%)and 2.385 km³(0.50%), respectively.Along the Himalayas from east to west,the number of glaciers decreased more in the east, whereas the size and volume decreased more in the west with glaciers relatively stable in the middle.On one hand, the glaciers retreated in the north, northeast and east, with the loss of the number and size being the highest in the north, followed by the northeast and the east. Meanwhile, the reduction rate of the glacier number and size was the highest in the east and northeast, respectively, and lowest in the north. While the size decreased mostly in the average slope of 10° to 15°, the number decreased mostly in the slope of 30° to 35°. The glacial retreat was most significant at 5,500 to 6,000 m elevations, followed by 5,000 to 5,500 m.The reduction rate was the highest at 3,500 to 4,000 m elevations,and lowest at 6,000 to 6,500 m elevations.Decreases in the glacial number and size were obvious in the Yarlung Zangbo River Basin (5O2), followed by Langqin River Basin (5Q2)and Pengqu (5O1), but least in Zhari Nanmucuo (5Z3). The retreat or disappearance of a large number of smaller glaciers, accompanied by the retreat of larger ones, is the main cause of glacier changes in the Himalayas. There is a close relation between glacial retreat and climate change in the Himalayas. Analyzing the annual mean temperature and annual precipitation over the past decades, the annual average temperature has increased significantly since the 1961’s, whilst the annual precipitation has increased or decreased. The temperature rise and precipitation drop may have caused the glacial retreat in the survey period.