白鹤滩库区蓄水前活动性滑坡InSAR早期识别研究——以葫芦口镇至象鼻岭段为例

EARLY INSAR IDENTIFICATION OF ACTIVE LANDSLIDE BEFORE IMPOUNDMENT IN BAIHETAN RESERVOIR AREA-A CASE STUDY OF HULUKOU TOWN XIANGBILING SECTION

白鹤滩水电站为我国仅次于三峡水电站的第二大水电站,库区葫芦口—象鼻岭库岸段居民点较多,库岸稳定问题是关注的重点。由于该库段受地形地貌、构造作用、复杂地层等影响,蓄水前可能存在现今正在发生微小变形且高位隐蔽的活动性滑坡,水库蓄水和运行期间,可能会进一步加剧此类滑坡变形,严重威胁周边居民生命财产安全,因此,蓄水前对该库段活动性滑坡进行有效识别与分析具有重要意义。本研究利用Sentinel-1A升降轨和ALOS-1升轨卫星,基于地形可视性的SBAS-InSAR(Small Baseline Subset-InSAR)技术对该重点库段的活动性滑坡进行了有效识别,共识别出27处活动性滑坡,野外验证最终确定23处,其中12处坡脚涉及蓄水位线。统计发现研究区活动性滑坡在10°~40°,坡向为东北、西北方向以及相对高差小于500 m条件下发育最多,大部分受断层控制,不受断层控制的滑坡灾害所处岩层强度较低。其研究成果有利于水库运行期间滑坡的预防与预警,整体技术流程与识别分析方法也可为今后复杂地形下的区域活动性滑坡识别与分析提供重要的参考依据。

Baihetan Hydropower Station is the second largest hydropower station after the Three Gorges hydropower station in China.There are many residential areas in Hulukou Xiangbiling reservoir bank section of the reservoir area.The stability of the reservoir bank is the focus of attention.Due to the influence of topography,tectonics and complex strata in this reservoir section,there can be active landslides with small deformation and hidden high position before impoundment.During impoundment and operation of the reservoir,such landslides can further aggravate the deformation and seriously threaten the life and property safety of surrounding residents.Therefore,it is of great significance to effectively identify and analyze the active landslide in the reservoir section before impoundment.In this study,the active landslides in this key reservoir section are effectively identified by using Sentinel-1A ascending and ALOS-1 ascending satellites and SBAS-InSAR(Small Baseline Subset-InSAR)technology based on terrain visibility.A total of 27 active landslides are identified,and 23 are finally determined through field verification,of which 12 slopes have their toe involving water level lines.Statistics show that active landslides in the study area develop most when the slope direction is northeast and northwest and the relative height difference is less than 500 m.Most of them are controlled by faults.The rock stratum strength of landslide disasters not controlled by faults is low.The research results are conducive to the prevention and early warning of landslides during the operation of the reservoir.The overall technical process and identification and analysis method can also provide an important reference basis for the identification and analysis of regional active landslides under complex terrain in the future.