The recent massive mud and debris flood in Dharali and Harsil of Uttarkashi not only caused massive destruction but also created a temporary lake in the Bhagirathi river. An expert team of geologists has studied this unique phenomenon and revealed the reasons behind it. The disaster also affected the nearby Harshil town, where roads, helipads and several buildings were submerged in water.
Devastation in Dharali and Harshil
Heavy rains on August 5 wrecked havoc in Dharali and Harshil in Uttarkashi. According to the administration, one person died in this disaster, while 68 people are missing. The disaster also had a profound impact on the army camp near Harshil, where nine people, including a Junior Commissioned Officer and eight soldiers, went missing. Several buildings collapsed and there was a major change in the geographical structure of the area.
Temporary lake formed
The team of experts visited the affected areas on August 12 and found that a local drain called Telgad near Harshil overflowed due to heavy rains. A huge amount of debris and water flowed from this drain and got deposited at the confluence of Bhagirathi river. This debris formed a huge fan-shaped sediment (alluvial fan), which blocked the original course of Bhagirathi river. As a result, a temporary lake about 1,500 meters long and 12-15 feet deep was formed on the right bank of the river.
Changed geographical structure of the river
This disaster also affected the banks of Bhagirathi river. The sand dune on the right bank was washed away in the strong flow of water, while new sediment was deposited on the left bank. This put the northern part of Harshil town in danger. The army camp and the guest house of Garhwal Mandal Development Corporation also suffered partial damage due to continuous rock erosion.
Geologists found that the deposited debris was weak due to excessive moisture, due to which the use of heavy equipment like JCB was not possible. Based on the resources available locally, experts made a plan to remove the debris and control the flow of water. Under this, small channels of 9-12 inches deep were made so that the water of the lake could be drained out slowly.
Strategy for controlled water drainage
After discussions with Uttarkashi District Magistrate Prashant Arya and SDRF Inspector General Arun Mohan Joshi, it was decided that the lake water should be drained out in three-four phases so that the danger of sudden floods in the lower areas could be avoided. SDRF and the irrigation department immediately started working on this plan. After two days of continuous hard work, success was achieved in draining the water from the lake in a controlled manner.
