多时间基线集时序InSAR形变监测:以平寨水库为例

Deformation monitoring from InSAR with multi-time baseline sets:a case study of Pingzhai Reservoir

时间基线对于时序InSAR形变提取有着重要影响。本文针对植被覆盖率与含水量较高、地形起伏较大的山地区域形变信息提取较困难的问题,以贵阳市平寨水库为研究区,获取Sentinel-1A雷达卫星2019年1月至2020年12月的历史影像数据,构建不同时间基线集,对比分析提取的地表形变信息;按照时间基线和最短的原则,选择最适宜研究区形变提取的基线条件,基于SBAS-InSAR技术获得研究区两年的沉降速率情况。结果表明,该研究区域时间基线集为60 d时提取的形变信息最为准确,存在误判和缺漏较其他时间基线集少。同时,结合贵阳市2019—2020年月平均降雨量数据及几何水准监测数据,分析了坝体形变时序变化与降雨量的关系,得出降雨量与坝体形变存在较强相关性,且基于SBAS-InSAR技术提取的形变信息与水准监测结果具有趋同性的结论。

Time baseline plays an important role in temporal InSAR deformation extraction.Aiming at the problem of difficult extraction of deformation information in mountainous areas with high vegetation cover and water content and large topographic relief,the historical image data of Sentinel-1A radar satellite from January 2019 to December 2020 are acquired with Pingzhai Reservoir near Guiyang as the study area,and different time baseline sets are constructed to compare and analyse the extracted surface deformation information.The baseline conditions that are most suitable for the extraction of deformation in the study area are selected by the principle of shortest time baseline sum,and the subsidence rate of the study area for two years is obtained based on the SBAS-InSAR technique.The results show that the most accurate deformation information is extracted from the 60 d time baseline set in the study area,and there are fewer misjudgments and omissions than other time baseline sets.The relationship between the temporal variation of dam deformation and rainfall is also analysed in the context of the average rainfall data from 2019 to 2020 in Guiyang and geometric level monitoring data.It is concluded that there is a strong correlation between rainfall and dam deformation,and it is also concluded that the deformation information extracted based on the SBAS-InSAR technique is convergent with the level monitoring results.