1978-2015年喀喇昆仑山克勒青河流域冰川变化的遥感监测

本文采用1978、1991、2001和2015年的Landsat MSS、TM、ETM+和OLI遥感影像,通过遥感图像计算机辅助分类和目视解译等方法提取冰川边界,分析喀喇昆仑山克勒青河流域冰川在1978-2015年间的进退变化。结果表明：1978-2015年间研究区冰川面积由1821.70 km2减少至1675.92 km2,减少145.78 km2,占1978年冰川总面积的8.00%;冰川消融率较低,在气候变暖的背景下反而呈现出退缩速率由快变慢的趋势。研究区东南向冰川退缩率明显高于西北向,冰川退缩率随冰川规模的增大而减小。研究区内有27处冰川在1978-2015年间发生过特殊的前进现象,面积与长度显著增加。其中,木斯塔冰川西侧冰川末端在1996-1998年间前进速度为904 m/a,乔戈里冰川东侧冰川末端在2007-2009年间前进速度为446 m/a,5Y654D0097冰川末端在1978-1990年间前进速度为238 m/a,初步判定这三条冰川为跃动冰川。以10 a为滞后期分析研究区周边气象站点资料发现：研究区气温持续升高,降水量以1981年为分界点呈现“先减后增”趋势是冰川退缩速率减慢的原因之一;此外,亚大陆型冰川性质、巨大山势条件和高山冷储作用,也可能是冰川退缩幅度较小的原因。

Variation of glaciers in the Shaksgam River Basin,Karakoram Mountains during 1978-2015

Based on Landsat MSS/TM/ETM+/OLI images of 1978, 1991, 2001, and 2015, glacier boundaries in the Shaksgam River Basin, Karakoram Mountains were extracted using computer aided image classification and visual interpretation methods, and the changes of glaciers in the study area were analyzed. The results show that the total area of glaciers in the study area was reduced from 1821.70 km2 to 1675.92 km2 during 1978-2015, by 145.78 km2, or 8% of the total area of glaciers. Under the background of climate warming, however, the rate of glacier retreating shifted from fast to slow in nearly 40 years. In the study area, the glacier retreat rate on the southeastern aspect was significantly higher than on the northwestern aspect. Glacier retreat rate decreased with the increase of scale of glaciers. There were 27 typical glaciers that clearly progressed during 1978-2015, with areas and lengths significant increased. Among these, the velocity of change for the western side of the Wood stark glacier was 904 m/a during 1996-1998, the velocity of change for the eastern side of the K2 glacier was 446 m/a during 2007-2009, and the velocity of change for the 5Y654D497 glacier was 238 m/a during 1978-1990, respectively. These three glaciers seem to be the surge-type glacier. By analyzing the climate records and glacier variation in the study area, it was concluded that higher temperatures led to the glacier retreat of the study area, but increasing rainfall to some extent inhibited glacier retreat. Topographic condition and the scale of glacier were key factors for glacier changes as well.