西藏桑日山区石冰川关键参数光学遥感反演

With the social and economic development, human activity gradually extended to higher and higher altitudes. That is more and more various engineerings, like hydropower station, high pressure power transmission line, were built in high mountains. Rock glaciers, as a special periglacial phenomena located at high altitudes, is the pile of rock and other material. But the rock glaciers always move downward due to the ice core or the ice cemented matrix involved in the rock debris. Thus the stability of rock glaciers will have a significant impact on the construction. Although, there were some researches about the distribution and the movement of rock glaciers, the number is much smaller than the total rock glaciers, and no more information about rock glaciers after 1990s. much potential disaster as rock glaciers, talus slopes, stone rivers, rockfalls distributed in the up part of the Yalung Zangpo river in Sangri in Tibet. In view of this , the project intends to select Shannan district as the study site to extract the boundary of rock glaciers automatically using satellite remote sensing images of different resolution (1m, 2m, 5m and 10m), like Geo-eye, IRS-P5, Spot5, and ASTER images, based on the texture feature of rock glaciers. The images should be corrected to orthoimages before extracting rock glacier boundaries combined with 1:50,000 and 1:100,000 topographic digital elevation models using GIS software. the accuracy of automatic extraction methods will be assessed by GPS and GPR field ground-penetrating radar to assess the accuracy. Moreover, we also try to measure the moving rate based on high-resolution remote sensing images using the maximum correlation coefficient method. The accuracy of measurements can be assessed by repeated GPS observation. Finally, weather data was employed to analysis how the rock glacier changes under the background of climate changes combined with multi-period boundaries and velocities of rock glaciers.

石冰川作为一类特殊的冰缘地貌现象，分布在高海拔山区，由岩块等松散物质构成的堆积体，内部含冰胶结体或冰核在重力作用下发生蠕变，使石冰川具有运动特性，其稳定性对下游工程建设具有重大影响。国内对石冰川分布和运动已有一定研究基础，但是数量较少，且90年后期研究中断。西藏西藏桑日县境内的雅鲁藏布江段，河谷两侧陡峻地形上方发育的石冰川、岩屑坡、石河、岩崩、坍塌等的潜在危害。鉴于此，本项目以该河段为重点研究区，利用多时相、多分辨率遥感数据，结合数字高程模型、野外考察和GPS测量等，探讨建立石冰川边界和表面运动速度的提取方法，通过获取研究区不同时期石冰川末端位置和表面运动速度的变化系列，分析该地区石冰川规模和动力特征变化规律，为石冰川稳定性和潜在危害评估提供方法支持和基础数据。

全球变暖背景下石冰川运动加快，意味着向下游搬运碎石（泥石流的物质源）的能力增加，石冰川可能是冰冻圈地区未来重要的致灾因素之一。随着社会经济和技术水平不断提高，人类活动范围不断扩大，越来越多的工程建设向偏远的高海拔山区推进，不可避免地面临石冰川问题。拟建于雅鲁藏布江中游桑日~加查峡谷段的1级电站巴玉水电站上游是否存在不稳定的石冰川分布受到关注。鉴于此，本项目利用0.5 m分辨率GEOeye-1遥感影像，通过石冰川特有的纹理特征，通过人工解译识别拟建巴玉水电站上游的石冰川分布信息。结合1970年的CORONA影像和地形图DEM和SRTM数据，分析石冰川的表面运动速度和表面高程变化，得到如下结论：1）在拟建的巴玉水电站上游石冰川集中在雅鲁藏布江北侧上游，共有27条石冰川，覆盖面积为12.2±0.9 km2，平均面积为0.5 km2，平均长度为1456 m，平均宽度为280 m。2）石冰川分布在海拔4570 m~5720 m之间，平均末端海拔为4920 m。属于舌状冰川群，一半左右石冰川处于活跃期，其中5条石冰川发生前缘垮塌现象，可能引起泥石流等大型灾害。3）对比CORONA影像和GEOeye-1影像的纹理特征显示，石冰川表面运动速度为0.3m/a~1.0 m/a。4）对比1970的地形图DEM和2000的SRTM结果表明，平均石冰川表面高程变化呈现微弱的减薄，但存在较大的差异性。