Glacial lake outburst flood at Kedarnath, Indian Himalaya: a study using digital elevation models and satellite images

Abstract

Kedarnath (3,533 m, 30°44′05″N, 79°04′02″E) is situated within a kilometre of the termini of the Chorabari and Companion glaciers in the Indian Himalaya. An outburst flood from a lake (3,845 m) formed by right lateral moraine of the former caused severe damage to the village on 17 June 2013. We determined various physical parameters of the lake from three digital elevation datasets (CartoDEM, SRTM and ASTER) and selected the SRTM-derived data as they appeared to portray the region more accurately. The obtained parameters were used in predictive equations suggested by different authors to estimate peak discharge of the flood. We also compared high-resolution images of 10 December 1965 (Corona), June 2011 (Bing) and 25 June 2013 (Catrosat-1 Pan + LISS-4mx) to assess the damage caused to the village besides other geomorphic changes. The results showed that at least 149 mm of rainfall in its 291-ha catchment was required to fill up the lake, without considering the presence of antecedent water and loss from seepage and evaporation. At the point of breaching, the lake released 0.43 × 106 m3 of water with a peak discharge of 1,352 cumecs. The north-western section of Kedarnath village was on the direct path of the debris flow triggered by the flood and was almost completely destroyed. The southern and south-eastern sections were least affected. Out of 37,299 m2 of pre-event roof area of Kedarnath (259 structures), 44.2 % were obliterated and 26.7 % were partly damaged, representing 138 and 56 structures, respectively. Only one-quarter of the structures of the village emerged intact or slightly affected after the event.