Search

The pre-failure evolution of landslides is of great value for the analysis of landslide triggering factors and post-disaster stability assessment. At present, optical images are commonly employed to ana⁃ lyze the pre-failure evolution, but it is well-known that their data availability could be highly limited due to the presence of clouds. With the advance in radar remote sensing and interferometric synthetic aperture radar(InSAR), it could provide a new technical approach for landslide pre-failure detection. In this paper, the 2018 Nanyu landslide in Gansu Province is utilized to demonstrate the capability of InSAR to trace its pre-failure surface displacements using European Space Agency’s Sentinel-1 radar data with a temporal interval of 12 days in different tracks. The results show that the landslide began to deform in June of 2017, and the maximum cumulative deformation reached up to 77 mm in the 13 months before the occurrence of the landslide. The time series InSAR derive displacements and the rainfall data is consistent, suggesting that the rainfall should be one of the triggering factors for the landslide. The study demonstrates the potential of radar interferometry for landslide detection, which can provide insights on landslide triggering factors, landslide disaster prevention and mitigation, and even landslide monitoring and early warning work in the future. [ABSTRACT FROM AUTHOR]

Lots of large hydropower engineering projects have been built in Jinsha River, Lancang River and Yalong River basins in the southwest mountainous areas of China. But the complicated stratum, lithology, structure, hydrology and other geological conditions of these river basins cause widespread, large number and high frequency of reservoir landslide for large hydropower engineering projects. Synthetic aperture radar interferometry(InSAR)technology with the advantages of wide coverage, high monitoring accuracy, and unblocked by clouds, brings new opportunities for early identification and monitoring of reservoir landslide. Especially in recent years, great attention has been paid to the construction of hydropower engineering projects and the reservoir geohazard prevention. The application of InSAR early identification and monitoring of reservoir landslide for large hydropower engineering projects in southwest mountainous area of China was sorted out, and the overall change analysis was carried out from the perspectives of research time, research content and research object. By summarizing the research status and hotspots of InSAR early identification and monitoring of reservoir landslides in southwest mountainous area, it is revealed that Baihetan hydropower engineering project is a milestone and nowadays has entered the outbreak stage of InSAR technology application and research on reservoir landslide. Meanwhile, the different application requirements of InSAR technology and the applicability of InSAR algorithm in the whole life cycle of hydropower engineering project(including the stage before impoundment, impoundment stage and the stage after impoundment)were discussed. In future, with the improvement of SAR data quality and algorithm, InSAR technology will be routinely involved in the identification and monitoring of reservoir landslides throughout the life cycle of hydropower engineering projects. It can provide important support for the early identification, monitoring and early warning, and trigger mechanism research and geohazard prevention of reservoir landslide, so as to enhance the ability of the reservoir geohazard prevention in China. [ABSTRACT FROM AUTHOR]

Objectives: The Sichuan-Tibet railway is not only a state key project in China, but also the most difficult super project in railway construction history due to the most complex terrain and the active geological structure. Interferometric synthetic aperture radar (InSAR) has proved to be a critical tool for detecting and monitoring geohazards because of its wide coverage, high precision, and high efficiency. However, due to its side-looking geometry, InSAR faces serious geometric distortions in mountainous areas, particularly in extremely steep high mountain and gorge areas along the Sichuan-Tibet railway. Methods: Utilizing the full open-access Sentinel⁃1 data, which has the wide coverage and a short revisiting time, we carry out satellite radar geometric distortion and feasibility analyses along the Sichuan-Tibet railway. Taking into account synthetic aperture radar(SAR) imaging geometry, the variations of the incidence angles across the whole SAR image, and the passive geometric distortions, we present an integrated approach to accurately determine the areas with SAR geometric distortions. Results: Our results for Sentinel-1 data show that the areas with geometric distortions for observations with a single-orbit (i.e. ascending or descending) reach 31%—35% along the Sichuan-Tibet railway, whilst the geometric distortion areas reduce to 1.5% for observations with both ascending and descending orbits; furthermore, about 35% of the whole area is suitable for joint analyses with both ascending and descending observations. Conclusions: The quantitative result also reveals the feasibility to use the Sentinel-1 data to detect and monitor geohazards along the Sichuan-Tibet railway from the perspective of geometric distortions. It can not only improve the overall understanding of the applicability of Sentinel-1 based InSAR and the InSAR results interpretation in this area, but also provide a guideline for efficiently selecting other satellite SAR datasets for detecting and monitoring geological disasters along the Sichuan-Tibet railway. [ABSTRACT FROM AUTHOR]