Estimating Landslide Deformation in the Upper Ganges Catchment Using Sentinel-1 Persistent Scatterer InSAR

Landslides are a significant threat to the population of the Indian Himalayas during monsoon seasons. In particular, the Upper Ganges Catchment is prone to major and minor landslides duringthe monsoon season each year. In 2013, due to the early arrival of the monsoon season by a few weeks, a major natural disaster happened that is now considered to be the largest disaster in the last 1000 years. High-resolution observations of landslide activity are required to help mitigating hazards and losses. However, since 2013, landslide deformation rates have remained unchecked in the Upper Ganges Catchment as it is logistically challenging and time-consuming in this remote area with severe topographies. Satellite-based Interferometric Synthetic Aperture Radar (InSAR) offers millimeter-scale measurements of ground surface deformation, which can detect and monitor slow-moving landslides in remote areas where ground-based monitoring approaches are impossible. In this study, we use Sentinel-1 satellite SAR data and the PS InSAR approach to examine the rates of landslide deformation in the Upper Ganges Catchment in the aftermath of the tremendous 2013 flood. Sentinel-1 acquired its first image in the region on 20/03/2017; therefore, we use Sentinel-1 between the year 2017-2019 and 2020-2022 acquired in both flight directions, ascending (path-129, frame-97 for the year 2017-2022) and descending (path-63, frame-489 for the year 2017-2019), (path-63, frame-492 for the year 2020-2022). We analyze single look complex (SLC) products in Interferometric Wide-Swath (IW) mode using SNAP software.The topographic phase component is removed using SRTM digital elevation model. Then, we use StaMPS software to perform PSI analysis.