Mapping of Annual Ground Displacement Using Remote Sensing Methods for Critical Slopes Along the Bhagirathi River in Uttarakhand, India

Abstract

The transportation route connecting the Tehri dam with Koteshwar Dam (Stage 2) in Uttarakhand, India is largely affected by the road cut slope failures. The rise and fall in the reservoir water level have also led to gradual ground subsidence at a few locations. In this study, two slopes at prime locations, namely Zero Bridge and Chainage 1.60 km from the Zero Bridge, have been studied for the magnitude of displacements using synthetic aperture radar (SAR) microwave data and LISS IV optical data over a selected time period. The permanent scatterers synthetic aperture radar (PS-InSAR) interferometry process was carried out in SARPROZ software at a coherence level set to 0.4. Total 57 scenes of Sentinel-1 SAR data from June 2015 to May 2018 have been undertaken for PS-InSAR processing. Persistent Scatterer Interferometry (PSI) results have shown ground deformation to the tune of 60 mm/year at the location Zero Bridge and at location 1.60 km from the Zero Bridge, no movement was observed. Whereas the correlation among the multi-spectral data (LISS IV) considering the study locations (Zero bridge and 1.60 km) have shown a pixel shift (slope surface displacements) for the time period spanning between the year 2012–2013 and 2014–2015.