GLOF Threat in Himachal Pradesh

Himachal at high risk of floods due rise in number of Supra glacial lakes formed by melting snow: Study

According to the studies carried out by the Centre, number of such lakes in Satluj basin has increased from 38 in 1993-94 to 390 in 2015.

SHIMLA- Scientists have already warned Himachal Pradesh about quakes and, indeed, abnormal seismic activity in the Himalayan belt was observed during past couple of years. Now, the State Centre on Climate Change of the State Council for Science Technology & Environment has warned Himachal Pradesh regarding devastating floods as melting of glaciers is causing formation of more lakes. Outburst of these lakes could unleash massive amount of water leading to floods.

The government has been advised to regularly monitor changes in these lakes, especially the smaller one in the higher Himalayan region of the State. Attention of government in this case is critical for averting any future eventuality in Himachal and loss of precious human lives, said the Centre.

Morain dammed lake in chandra basin

Example: Photographical representation of how the Moraine Dammed Glacial Lake looks like in the Satellite Image-vis-à-vis the Field

To understand the situation, which is in this case is rapid growth in formation of small lakes due to retrieval of glaciers, let’s go through some review.

The state of Himachal Pradesh invariably experiences flash floods, the cause of which is unknown. In the year 2000, the Satluj valley experienced the heaviest floods causing economic loss of more than 800 crores. The cause of this flood event was not known to the experts that whether the floods were caused by cloud bursting or due to Glacial Lake Outburst Floods (GLOF) phenomena as it started from the Tibetan Himalayan Region.

GLOF Threat in Himachal Pradesh

Satellite and Field photograph of Moraine Dammed lake at the Snout of the Geepang Gath Glacier in Chandra Basin,District Lahaul & Spiti, H.P.

The formation of landslide dammed lakes in high altitude zones such as Parachoo in the upper catchment of Spiti basin in Tibet caused tremendous threat to the life and property located in the downstream areas since its inception in the year 2004.

The recent tragedy of 2013 in the Uttrakhand Himalaya has also been correlated with the bursting of a lake having a total area of about 08 hectare in front of the snout of the Chorabari glaciers that caused widespread damage in the downstream areas besides the heavy rainfall in the area.

Causes and Threats of GLOF

As per various studies carried out in the past, Himalayan glaciers are in a state of general retreat since 1850. In the Himalayas, during the retreating phase a large number of lakes are being formed either at the snout of the glacier as a result of damming of the morainic material known as moraine dammed lakes or supra glacial lakes formed in the glacier surface area.

Most of these lakes are formed by the accumulation of vast amounts of water from the melting of snow and by blockade of end moraines located in the down valleys close to the glaciers. In addition, the lakes can also be formed due to landslides causing artificial blocks in the waterways. The sudden break of a moraine/block may generate the discharge of large volumes of water and debris from these glacial lakes and water bodies causing flash floods namely GLOF.

The sudden bursts of lakes can happen due to erosion, a buildup of water pressure, an avalanche of rock or heavy snow, an earthquake, or if a large enough portion of a glacier breaks off and massively displaces the waters in a glacial lake at its base. There are number of such events that have happened in Nepal Himalayas but no such event has been reported so far from Indian Himalayas.

According to the State Centre on Climate Change of the State Council for Science Technology & Environment, which has been carrying different studies in the Himachal Himalaya since 1993, number lakes has increased manifold in last two decades.

Lake Formation Increasing River Basins

Satluj Basin

GLO Floods In Himachal Pradesh

According to the studies carried out by the Centre, number of such lakes in Satluj basin has increased from 38 in 1993-94 to 390 in 2015.

Out of these 390 lakes, 42 lakes have area more than 10 hectare, 45 between 5-10 hectare, and remaining 303 lakes have an area less than 5 hectare.

Chenab Basin

Chenab Basin Glacier Lakes

Likewise the Chenab basin which mainly originates from the Himachal Himalaya, total number of lakes has increased from 116 in 2013 to 192 in 2015, which is almost four times than the number of lakes identified during 2001.
Out of these 192 lakes, 04 lakes have area more than 10 hectare, 6 lakes between 5-10 hectare and 182 are the small ones having area less than 5 hectare.

Beas Basin

Beas Basin Glacier Lakes
In the Beas basin, number of lakes has gone up from 67 lakes during 2013 to 89 lakes in 2015, revels satellite data. Further analysis of these 89 lakes reveals that 80 lakes are smaller one having area less than 5 hectare, 07 lakes with aerial range between 5-10 hectare and 02 lakes which are having area more than 10 hectare.

Ravi Basin

Moranic Lakes in Himacahl PRadesh
The Ravi basin had total 22 lakes in 2013, which has now increased to 34 in 2015. When seen based on aerial distribution ,it is found that 03 lakes are having area more than 10 hectare, only 01 lake is having area between 5-10 hectare and 30 lakes are such which have area less than 5 hectare.

Need of time

Number of lakes in Himalayan River Basins

Based on the above analysis carried out by the Centre for the year 2015, it is evident that there is a considerable increase in the number of moraine dammed lakes (GLOFs) in each basin which reflects that formation of such lakes in the Higher Himalayan region is indicating an increasing trend. The higher number of smaller lakes i.e. lakes with area less than 5 hectare indicates that the effect of the climatic variations is more pronounced on the glaciers of the Himalayan region resulting in the formation of small lakes in front of the glacier snouts due to the damming of the morainic material.

The lakes with area more than 10 hectare and those with area between 5-10 hectare are more vulnerable sites for causing damage in case of bursting of any one of them.

Therefore, a proper monitoring and change analysis of all such lakes in higher Himalayan region of the State is critical for averting any future eventuality in Himachal Pradesh, so that the precious human lives are saved.

Another aspect of this report is about climate change caused by rising carbon emissions. Himachal need to pay attention to check air pollution. Currently, the Chief Minister Virbhadra Singh and his minister hardly believe in theory of global warming or glacier melting. Annoyed over NGT’s ban on fossil fuel vehicles into Rohtang Pass region, the CM had claimed that there are actually no glaciers around Rohtang. Vehicular emissions are excess and widespread with literally no check on it.

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