1990—2015年喜马拉雅山冰川变化的遥感监测

基于Landsat系列遥感数据,运用比值阈值法（B3/B5）和目视解译,研究1990—2015年喜马拉雅山冰川面积的分布与变化特征。结果表明：25年间研究区冰川面积共减少2553.10 km²,年均退缩率为0.44%/a,研究时段冰川加速退缩。研究区冰川主要分布在西段地区,中段次之,东段最少,近25年来西段、东段和中段地区冰川均表现为退缩趋势,其中东段地区退缩最快,中段最慢。从地形分布和变化特征看,5°~25°范围内冰川的分布面积较多,近25年来各坡度等级冰川均在退缩,其中25°~30°之间冰川面积退缩较快,在极平缓/极陡峭地区退缩较慢。尽管8个坡向上冰川均表现为退缩趋势,但退缩幅度有所差异,北坡与西北坡冰川退缩较慢,其他坡向退缩较快。研究时段表碛物覆盖型与非表碛物覆盖型冰川均在退缩,但后者的退缩幅度较大,表明研究区表碛物在一定程度上抑制了冰川消融。

Glacier variations in the Himalayas during 1990-2015

Based on the Landsat remote sensing information, visual interpretation and ratio threshold method are adopted to analyze the specific characteristics of the glacier area and changes in the Himalayas from the beginning of 1990 to 2015. The results demonstrated that the glacier area in the study area decreased by 2,553.10 km² for the past 25 years, with an average annual retreat rate of 0.44%/a. During the study period, the rate of glacier retreat accelerated; some of its glaciers were distributed in the western section, followed by the middle section; the least is the eastern section; the eastern, central, and western sections of the glaciers showed a trend of retreat. The eastern section had the fastest retreat speed, while the central section had the slowest. In terms of the distribution of terrain and the characteristics of changes, most of the glaciers are distributed in the range of 5° to 25°. In recent 25 years, glaciers of all slope grades had shrunk, and the glacier area retreated faster between 25° and 30°, and more slowly in extremely gentle/steep regions. Although all the 8 slopes showed a retreat trend, the extents of retreat were different. The glaciers on the north and northwest slopes retreated relatively slowly, while in the other slope directions, the glaciers shrank relatively quickly. In recent 25 years, both debris-covered and non-covered glaciers retreated, but the latter had retreated greatly, suggesting that the surface debris inhibited the glacier melting in the study area.