The heavy rains experienced in Uttarakhand on June 16-17 have triggered over a thousand landslides, mostly in river valleys.
The National Remote Sensing Centre (NRSC), Hyderabad, has released data on the landslides as part of the landslide inventory being carried out for the affected areas using pre- and post Indian Remote Sensing (IRS) data. According to the Centre, a total of 1,356 landslides have been detected in the preliminary assessment.
The area in and around Kedarnath witnessed large-scale occurrence of floods and landslides between June 16 and June 17 due to incessant rainfall upstream of Mandakini river and its tributaries. The NRSC is carrying out a landslide inventory using pre and post IRS data. The data used for the study includes semi-automatic detection of landslides using standard algorithms used in order to detect the landslides and generate the outputs.
The detected landslides here include existing landslides of which some are reactivated, with a total of 1,356 landslides being identified along the river valleys of Mandakini, Mandani, Kali, Madhyamaheshwar and parts of Alaknanda valley from Srinagar to Chamoli. The major towns included in this area include Kedarnath, Sonprayag, Gaurikund, Ukhimath, Guptkashi, Mansuna, Phata, Agastyamuni, Rudraprayag, Srinagar, Gauchar, Karnaprayag, Nandprayag and Chamoli, among others.
At present, the sections along the river valleys of Mandakini, Kali, Mandani, Madhyamaheshwar and parts of Alaknanda from Srinagar to Chamoli are completed and uploaded for visualisation on Bhuvan- a geoportal of Indian Space Research Organisation showcasing Indian earth observation capabilities. Other sectors will be continuously uploaded upon completion. According to the Centre, areas under snow, cloud cover and shadow could not be mapped. Considering this, it is quite possible that the actual number of landslides in the disaster-affected valleys is higher than the 1,356 identified. It will be recalled that the Uttarakhand Space Application Centre will also be using the satellite images provided by NRSC to assess the damage in the disaster-affected areas.