塔里木盆地南缘喀拉米兰河-克里雅河流内流区近30 a来的冰川变化研究

对1999年的喀拉米兰河克里雅河流内流区的Landsat ETM 影像运用非监督分类、监督分类,雪盖指数域值法和比值域值法提取其中176条冰川的边界信息,并与目视解译结果进行定量比较,结果表明:比值域值法精度最高,达98.32%;将比值域值法提取1999年的冰川边界与1970年航测地形图勾绘的冰川边界进行叠加分析,得到整个流域29 a来的冰川变化信息.统计表明,流域冰川条数减少了0.6%,总面积萎缩了2.86%,总冰储量减少了3.10%,大多数冰川处于稳定状态.

Glaciers fluctuations in the Karamilan-Keriya River Watershed in the past 30 years

Responding to the global warming,plenty of glaciers in West China have more or less retreated.In this study,the changes of glaciers in the interior drainage areas of the Karamiran-Keriya Rivers in the Kunlun Mountains were investigated using topographic maps(1970) and Landsat ETM (1999) imageries.Four methods,non-supervised classification,supervised classification,threshold values of NDSI and threshold values of band ratio,were used to extract the boundaries of 176 glaciers,including smaller ones and larger ones,in the Karamiran-Keriya Rivers,with Landsat ETM image,and compared with the results derived from visual interpretation.It is found that the method of threshold values of band ratio is the best.Glaciers fluctuations on the whole Karamiran-Keriya River watershed were estimated by comparing the glacier boundaries derived from Landsat ETM images in 1999 with that derived from topographic maps in 1970.If it is not certain for only using the method of threshold values of band ratio,visual interpretation is often used in order to enhance the accuracy.From 1970 to 1999,there were 5 glaciers disappeared,the total glacier area shrank by 2.86% and the ice reserve reduced by 3.10%.