基于时序Sentinel-1数据的锦屏水电站左岸边坡形变探测与特征分析

Detecting and characterizing deformations of the left bank slope near the Jinping hydropower station with time series Sentinel-1 data

水电站库岸边坡的稳定性监测是保障大坝安全运行的重要基础性工作,而形变探测是实现边坡稳定性监测的主要途径。星载合成孔径雷达干涉测量(interferometric synthetic aperture Radar,InSAR)技术因其具有观测精度高,可全天候全天时工作的特点,已成为一种重要的形变监测手段。本文采用小基线集时序InSAR技术处理了56景C波段Sentinel-1影像,提取了雅砻江流域锦屏一级水电站库区左岸边坡的形变特征信息。结果表明,锦屏一级水电站上游距离大坝约1.5 km处左岸边坡上存在一处表面积超过75万m 2 的大型滑坡体,2015-2018年间最大视线向形变速率超过200 mm/a。形变区主要集中在该岸坡中上部,观测时间段内视线向最大累积形变量超过 500 mm,其形变时间序列无明显周期性,基本呈线性滑动趋势。采用同样的方法,对2006-2011年间获取的22景L波段ALOS-PALSAR存档数据进行处理,结果显示在大坝蓄水前,该坡体基本保持稳定。由此推断,库区蓄水造成的大幅水位上升很可能是诱发该滑坡复活的主要因素。

tability monitoring of bank slopes along the reservoirs of hydropower projects is a fundamental task for the safety oFdam operation.And deformation detection is a major approach for stability monitoring.Spaceborne InSAR technique has been recognized as an effective tool for deformation detection with its high observation accuracy and capability to work independent of weather and solar illumination.The deformation information of left bank slope of Jinping hydropower station in the Yalong River Basin was obtained by processing 56 images of C-band Sentinel-1 data with small baselines time series InSAR technique.The result indicated that there was a large landslide on the left bank slope about 1.5 km away from the dam upstream of the Jinping I hydropower station,with a surface area of more than 750,000 square meters.The maximum deformation rate in the line of sight exceeded 200 mm/a from 2015 to 2018.The deformation area was mainly concentrated in the middle and upper part of the bank slope.And the maximum cumulative deformation of the line of sight in the observation period was more than 500 mm.The time series oFdeformation was basically a linear sliding trend without obvious periodicity.The same method was used to process 22 archived images of L-band ALOS-PALSAR data from 2006 to 2011.The results show that the left bank slope was stable before the reservoir impoundment.It is therefore inferred that the sharp rise of water level of the reservoir might be a main trigger factor for this landslide activation.