Integration of satellite remote sensing and geophysical techniques (electrical resistivity tomography and ground penetrating radar) for landslide characterization at Kunjethi (Kalimath), Garhwal Himalaya, India

Abstract

During the extreme precipitation event of 15th–17th June 2013 in Garhwal Himalaya, glacial lake outburst flooding accompanied by numerous landslides and flash flood events caused widespread death and destruction. Many hill slopes and steep river banks had developed fractures and fissures indicative of landslides and one such scarp was observed at Kunjethi (Kalimath) village on satellite images during routine analysis. Rainfall threshold analysis for years 2012, 2013, 2014 and 2015 has confirmed that it was the main triggering factor which happened due to extreme precipitation in June 2013 leading to scarp development and initiation of landslide. In order to characterize the landslide and get subsurface information, two highly cost-effective and fast non-invasive geophysical techniques, electrical resistivity tomography (ERT) and ground penetrating radar (GPR), were used. Four ERT profiles and one GPR radargram profile were used to determine the approximate depth to slip surface, which is inferred around 15–19 m. Integration of satellite remote sensing, geophysical studies and field observations have been used to demarcate the maximum possible slide zone. This study reiterates that earth observation tools in integration with faster, non-invasive and cost-effective geophysical techniques can establish the slip surface, which is an essential information required for landslide hazard mitigation measures.