12-14 September, 2011, Lucknow - Earth Science India

National Conference on Science of Climate Change and Earth’s Sustainability: Issues and Challenges ‘A Scientist-People Partnership’
12-14 September, 2011, Lucknow
winter precipitation in the form of snow as well. Therefore, the Leh area is described as
a cold desert, which has not witnessed such a rainfall in the recent past.
On the fateful night of August 5 th 2010, the rainfall recorded at the Air Force
Station at Leh, situated about 6 km from the catchment of Shaksaling nala was 12.8
mm. The rainfall lasted only for 15 minutes implying the cloud burst was highly
localized.
The sudden downpour resulted in runoff on the slopes, which had enough velocity
to initiate movement of overburden comprising gravel, boulder and sand-silt matrix on
the stream slopes. The water mixed with debris converted into a fast moving mass of the
muddy water with high velocities of flow, having great destruction potential as it flowed
down the streams. As a result , the debris flow over spilled the stream banks, laterally
spreading in a wide area and carving out new undefined channels in the low lying areas
causing widespread damages to the settlements falling along these newly carved out
channels.
In Leh area, the damage was confined to the catchment of Shaksaling nala,
flowing from an elevation of 3800 m to 3410 m. The debris flow mobilized and
damaged the settlements, bus stand building, BSNL building, hospital complex, radio
station, etc. in its 3 km run-out distance.
Further downstream, the debris flow washed away the bridge located near village
Sabu and spread out in the downstream commands having a run-out length of about 26
km before reaching the Choklamsar village. This caused huge damage in the
downstream Choklamsar village, ITBP Camp, Leh-Manali road, new Choklamsar
market, etc.
The bridges on Phyang, Taru, Umlah, Nimu, and Bazgo streams have been
completely washed away. The concrete abutments of some of the bridges have also
been severely damaged.
This type of cloud burst is a rare occurrence in the area. As the stream courses are
dry and only carry small quantity of discharge in the event of rainfall or snow melt, the
stream courses have been occupied by human settlements. The scarcity of potable water
prevailing in the area further compels the local population to construct houses in low
lying areas near the stream banks.
Therefore, it is concluded that due to change in the climatic regime of the Leh
area, the natural catastrophe has taken place. However, the lesson learned from this has
to be utilized to devise proper urban planning for the Leh area and no anthropogenic
activity may be allowed along the stream courses.
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