川西高原活动性滑坡识别与空间分布特征研究

In SAR-based indentification and spatial distribution analysis of active landslides in the Western Sichuan Plateau

成都平原向西至松潘-甘孜褶皱带完成了从平原到高山峡谷区的转变,区域内起伏落差巨大,地势奇峻,河流下切侵蚀严重,构造活动频繁,地震频发,内外动力作用强烈,地质灾害众多。文章利用覆盖全区的Sentinel-1A升降轨数据以及重点区域的ALOS-2数据进行InSAR技术处理,结合GIS空间分析,对研究区活动性滑坡进行早期识别以及空间分布规律的探索,再辅以部分野外调查佐证,获得了以下认识:研究区滑坡集中分布地区按其诱因可分为水库蓄水诱发灾害区(黑水县毛尔盖水库)、震后破碎山体灾害区(茂县岷江与黑水沟交界、汶川至理县一带、九寨沟至石鸡坝镇一线)和重要河流灾害区(舟曲、腊子口镇、小金县和丹巴县);区域内活动性滑坡主要分布于千枚岩等变质岩和泥页岩等碎屑岩中;主要地形范围为坡向南东、东、北东向,坡度15°~40°,高程区间1000~3000 m,相对高差>1000 m;主要分布断裂有岷江断裂、玛曲-荷叶断裂、光盖山-迭山北麓断裂和茂汶-汶川断裂。Sentinel-1A升降轨数据的结合,使得有效观测区域提高到研究区面积的73.41%。在川西高原区ALOS-2数据相对优于Sentinel-1A数据,ALOS-2和Sentinel-1A数据在九寨沟和茂县重叠区识别的结果重合率为58.7%和44.8%,识别数量前者分别是后者的3.98倍和1.39倍。

The Chengdu plain westward to the Songpan-Ganzi fold belt is a transition zone from basin to plateau. The region has huge undulation and fall, strange and steep terrain, severe river undercutting and erosion, frequent tectonic activities, and strong internal and external dynamics, resulting in frequent earthquakes and numerous geological hazards.The article uses Sentinel-1A data covering the whole region and ALOS-2 data in key areas for InSAR technology processing, combined with GIS spatial analysis, early identification of active landslide disasters in the study area and exploration of spatial distribution patterns, supplemented by field surveys to support the following understanding.According to the inducing factors of the disaster, the areas where the disaster points are concentrated can be divided into three zones: disaster zones induced by reservoir storage, such as Maoergai Reservoir in Heishui County;disaster zones caused by broken mountains after the earthquake, such as the junction of Minjiang River and Heishui Gully in Maoxian County, the area from Wenchuan County to Li County, and the area from Jiuzhaigou County to Shijiba Town;disaster zones cause by essential rivers, such as Zhouqu County, Lazikou Town, Xiaojin County, and Danba County. The active landslides in the region are mainly distributed in metamorphic rocks such as phyllite and clastic rocks such as shale. The disasters are mainly distributed in the terrain with aspects of SE, E, NE, slope greater than 15°, elevation interval of1000~3000 m, relative elevation difference greater than 1000 m, and curvature between-0.5~0.5. The disaster points are mainly close to the Minjiang fault, the Tazang fault, the Guanggaishan-Northern Dieshan fault, and the Maowen-Wenchuan fault zone. The combination of orbit-ascending and orbit-ascending data of Sentinel-1A increases the effective observation area to 73.41% of the total area. The ALOS-2 data are relatively better than the Sentinel-1A data in the western Sichuan plateau area. The coincidence rates of ALOS-2 and Sentinel-1A are 58.7% and 44.8%, respectively, in Jiuzhaigou and Maoxian, and the identified number of the former is 3.98 times and 1.39 times that of the latter.