Devastation in the Kedarnath (Mandakini) Valley, Garhwal Himalaya, during 16-17 June 2013: a remote sensing and ground-based assessment

The Garhwal Himalaya tragedy of 16-17 June 2013 was perhaps the worst disaster of the last century seen in India owing to unprecedented rainfall. The extreme rainfall together with bursting of moraine-dammed Chorabari Lake caused devastating flooding of the Mandakini River and its tributaries in the Garhwal Himalaya. Several downstream settlements such as Kedarnath (3546 m a.s.l.), Rambara (2740 m a.s.l.) and Gaurikund (1990 m a.s.l.) were damaged due to flash floods. The present study was taken up to assess the extent of devastation in the Mandakini Valley from Kedarnath to Sonprayag based on ground observations, repeated ground photography, discussion with local residents (eye witnesses) and analysis of pre-event and post-event high-resolution satellite data. Overall 137 'flash flood-induced debris flow' events were mapped in the Mandakini Valley between Kedarnath and Sonprayag which led to the catastrophe and miseries to the pilgrims. The area of 'flash flood-induced debris flow' and the main channel of Mandakini River were increased by similar to 575 and similar to 406 %, respectively, during the 16-17 June 2013 event. About 50 % (7 km) of the pedestrian route (14 km) between Gaurikund and Kedarnath was completely washed away which obstructed the rescue operations to evacuate pilgrims, tourists and local people after the 16-17 June 2013 event. The 'flash flood-induced debris flow' and moraine-dammed lake outburst events together washed away similar to 120 and similar to 90 buildings around Kedarnath shrine and in Rambara town, respectively, although the main Kedarnath temple survived with minor damage. The database of flash flood-induced debris flows and flood effected area generated in the present research will facilitate to other disciplines (e.g., future settlements planning) for long-term reconstruction work in the affected areas of the Mandakini Valley.