Monitoring of Landslides between Tehri and Koteshwar Dams in Uttarakhand, Himalayas

In the last few decades, the Himalayan region has undergone a tremendous amount of urbanization to host incoming tourists, pilgrims, and local people. To support such developments, hydropower is harnessed from the Himalayan Rivers through the construction of dams and development of artificial reservoirs. The rim of such reservoirs is susceptible to occurrence of landslides. These landslides may prove to be a major geohazard along the reservoir and could decrease the reservoir capacity to hold water, thereby, decreasing the utility of dams and threatening the life and infrastructure situated on the banks as well as downstream areas of the reservoir. With this motivation, we have monitored the landslide deformations in the region between Tehri and Koteshwar Dams for 1.5 years from January 1, 2021, to June 30, 2022. We have used the satellite interferometric synthetic aperture radar (InSAR) techniques to measure the deformation from Sentinel-1 SAR satellite data. We have used GMTSAR, SNAP, SNAP2StaMPS software to apply Persistent Scatterer Interferometry (PSI) and Short Baseline Method (SBAS) techniques of InSAR. We obtained the line of sight mean deformation between 20 mm and 60 mm in 1.5 years period using the SBAS method. Further, we obtained the line of sight deformation velocities between -1.1 mm/year to 5.3 mm/year using the PSI method. The results indicate that the region between Tehri and Koteshwar Dams is stable since January 1, 2021.