Current Science: Recent climate changes have had significant impact on high-mountain glacial environment. Rapid melting of snow/ice and heavy rainfall has resulted in the formation and expansion of moraine-dammed lakes, creating a potential danger from dammed lake outburst floods1.
On 16 and 17 June 2013, heavy rains together with moraine dammed lake (Chorabari Lake) burst caused flooding of Saraswati and Mandakini Rivers in Rudraprayag district of Uttarakhand (Figure 1a).
Prolonged heavy down pour on 16 and 17 June 2013 resembled ‘cloud burst’(except for amount of precipitation of 100mm/h) type event in the Kedarnath valley and surrounding areas that damaged the banks of River Mandakini for 18km between Kedarnath and Sonprayag, and completely washed away Gaurikund (1990masl), Rambara (2740masl) and Kedarnath (3546masl) towns. The roads and footpath between Gaurikund and Kedarnath were also damaged.
There are reports of loss of large number of human lives and damage to the property and livestock. The Chorabari Lake(3960masl) also known as Gandhi Sarovar Lake, is a snow melt and rain fed lake, located about 2km upstream of Kedarnath town which is approximately 400m long, 200m wide having a depth of 15–20m.
The bursting of this lake led to its complete draining within 5–10min as reported by the watch and ward staff of the Wadia Institute of Himalayan Geology (WIHG), who were present in WIHG camp at Chorabari Glacier on 16 June and early morning of 17 June 2013.
The heavy rainfall together with melting of snow in the surrounding Chorabari Lake washed off both the banks of the Mandakini River causing massive devastation to the Kedarnath town.
The WIHG meteorological observatory at Chorabari Glacier camp (3820masl) recorded 210mm rainfall in 12 hours between 15 June (5:00 p.m.) and 16 June (5:00a.m.) 2013. On 16 June 2013 alone from 5:00a.m.to 5:00p.m.), 115 mm rainfall was recorded, causing 325 mm rain in 24 hours.
The WIHG has another rain gauge installed at its geophysical facility (MPGO) at Kopardhar near Ghuttu (30.53N, 78.74E; 1836masl),which is approximately 38km (aerial distance) from Kedarnath. The Ghuttu rain gauge recorded 58mm on 15 June, 121mm on 16 June and 93mm on 17 June with no rainfall on 18 June (Figure 2).
The surface atmospheric pressure began to decrease on 15 June reaching a low (832.4mB) on 17 June (Figure 2). During 15–17 June 2013, the heavy rains also caused devastation in other regions of Uttarakhand, Himachal and Nepal.
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