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

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.