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Detection and Monitoring of Very Slow Landslides in Vicinity of an Artificial Reservoir using Advanced Differential SAR Interferometry: A Case Study of Tehri Region, India
  • Vishal Mishra,
  • Kamal Jain
Vishal Mishra
Indian Institute of Technology Roorkee

Corresponding Author:vmishra1@ce.iitr.ac.in

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Kamal Jain
Indian Institute of Technology Roorkee
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Abstract

Persistent Scatterer Interferometry (PSI) is a novel remote sensing technique for monitoring land deformation on large scale. It is economic and can be used for detection of land surface deformation in the past given that the sensor should have passed over the area. The millimetric precision of the technique makes it very useful. One of its application is monitoring of slow moving landslides. In this study we have focused upon monitoring of slow moving landslides in Tehri region of Uttarakhand state of India. This area is landslide prone. Its susceptibility to landslide has increased due to construction of artificial reservoir in the region. The variation in reservoir drawdown level can be cited as one of the reasons. In this study we have applied Persistent Scatterer Interferometry on the stack of 20 Single Look Complex (SLC) scenes of Envisat satellite of European Space Agency. We have performed time-series analysis for period starting from 12 May 2008 to 26 July 2010. The methodology consists of selection of master image, coregistration of other slave images to master image, calculation of amplitude stability index, generation of reflectivity map. After this 19 interferograms were generated. On basis of this selection of Persistent Scatterers (PS) is done. After that estimation and removal of Atmospheric Phase Screen (APS) was done. In the end calculation of time-series displacement of PSs is performed. From this analysis we are able to identify the spatial location of slow moving landslides. In this study we have identified PSs having nearly 40 mm/year of velocity. Detected areas showing land movement away from the line of sight of satellite, can be found on the rim of reservoir as well as areas 4 kilometres interior, away from the boundary of reservoir. These areas are located near roads and places where anthropogenic interference is there.