July 26, 2013
On June 16 and 17th 2013 catastrophic flooding occurred in Kedarnath, Uttarakhand, India due to excessive monsoon rains and the failure of a glacier moraine dammed lake. A detailed description of what led to the combined flows of the Mandakini and Saraswati River overwhelming Kedernath is provided by Dobhal et al (2013) in the most recent Current Science. issue. Here that analysis is supplemented with Landsat imagery from before and after the event. In each image Kedarnath is indicated with a yellow arrow and Chorabari Lake a red arrow. Chorabari Lake is impounded by the lateral moraine of the Chorabari Glacier and is a largely snow and rain fed lake that is not always present. The lake is adjacent to the terminus of debris covered Chorabari Glacier. In the Landsat images from 2000 and 2002 the lake is quite evident, and Kedarnath is on the outwash plain between the Saraswati and Mandakini River just 2 km from the lake and end of the glacier. The 2012 Landsat image is not as clear but the lake is still evident. In all three of these images there is a bright green vegetated area (GP) just north of Kedarnath that is between the Companion and Chorabari Glacier, protected by the lateral moraines of each.
The vegetation resumes immediately after Kedarnath. In the 2013 Landsat imagery from June 23 and June 30th the lake is no longer present. The extent of the vegetative free area around Kedarnath has expanded after the flooding. Dobhal et al (2013) report that, “…WIHG meteorological observatory at Chorabari Glacier camp recorded 210 mm rainfall in 12 hours between 15 June (5:00 p.m.) and 16 June (5:00 a.m.). On 16 June 2013 alone (from 5:00 a.m. to 5:00 p.m.), 115 mm rainfall was recorded, causing 325 mm rain in 24 hours. The Chorabari Lake is a snow melt and rain fed lake, located about 2 km upstream of Kedarnath town which is approximately 400 m long, 200 m wide having a depth of 15–20 m. The bursting of this lake led to its complete draining within 5–10 min 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 glaciers in this area have been retreating, which has led to formation of many new lakes, and has led to further vertical exposure of the lateral moraines from the Little Ice Age. The decreased buttressing of the moraines, the enhanced melting, and glacier retreat is leading to enhanced glacier involved outburst floods. Jaundhar Barak, Jaonli and Gangotri Glacier are other local glaciers impacted by recent retreat.
2000 Landsat image