81 / 2019-07-30 19:10:59

Monitoring Three Gorge Area Landslide by SAR Interferometry : Preliminary Results along Badong and Wushan River Bank

InSAR, Landslide, deformation, Three Gorge, Time series

水库地质灾害防治与生态环境保护 > 地质灾害监测预警

Three Gorge area landslide hazards developed very fast after the Dam started to impound the water. There were lots of research literatures concentrate on the Badong Huangtupo Landslide area for the whole city center had to change its position. Several literatures used Envisat SAR images time series to monitoring the surface deformation from 2008~2010. The results shows good consistent with the water level changes and precipitation. The high resolution TerraSAR Spotlight images had been used to monitoring the Shuping landslide and Fanjiaping landslide area in Zigui country from 2009~2012,the InSAR results showed good details of the landslide boundary and deformation rate with DInSAR technology. What is more, the corner reflectors mounted on the landslide area monitored by InSAR techniques are fully consistent with the GPS results.
This paper studies some landslide area in the Three Gorge by InSAR technology in the past few years, such as Huangtupo, Huanglashi , Daping and Baiheping landslide area , etc. al . The high resolution SAR images covered Badong and Wushan area have been collected., including the Sentinel-1, TerraSAR, RadarSAT-2, ALOS-2 SAR images. The high resolution topography in those landslide area have been collected both by UAV lidar and high resolution topography map.
The Huangtupo landslide area changed a lot in the past 4 years with the buildings ruins cleared and red soil covered by the local government. The time series results by Sentinel data in this area shows the big changes but could not derive reasonable deformation results. Several new designed dihedral corner reflectors have been mounted on the landslide area for the further study with ascending and descending RadarSAT-2 high resolution SAR image.
The preliminary results from those new acquiring SAR data series show that the traditional landslide area such as Huanglashi , Daping, Baiheping are all moving slowly with good coherence in SAR image series. The poor vegetation coverage in those landslide area helped to get the credible InSAR results. The high resolution DEM is the critical elements for the DInSAR techniques in those landslide area. The steep topography in those landslide area distorted the SAR images correspondingly. Combining with the descending and ascending orbit SAR images, the landslide area along the Yangtze River can be monitored. However, the orientation of the landslides is the key for deformation monitoring. The northern and southern direction landslide with less distortion both in ascending and descending SAR images. While, the eastern and western direction of landslide with steep topography are invisible in SAR images due to the foreshortening and layover.
The primary results shows that it is possible to use ascending and descending high resolution SAR images to monitor the landslide area with mm level precision, while the vegetation is not so dense. High resolution SAR interferometry helped a lot for the landslide boundary detection and detailed analysis. The lower resolution SAR images such as Sentinel-1 still could provide some deformation results in landslide area, but it need more auxiliary data to interpret the results.