Climate change, glacial melt, sedimentation and human activity are a toxic brew threatening the very existence of Uttarakhand
The unfolding disaster in Uttarakhand’s historic town of Joshimath shows why the section of the Himalayas in this state is extremely fragile. Joshimath’s sinking also shows (once again) why human interference could lead to apocalyptic consequences for Uttarakhand and also a large swathe of India.
Unusual weather events in the Uttarakhand Himalayas have already been showing an increasing trend. They are leading to an increase in the frequencies and magnitude of (spring season) forest fire events, avalanches, flash floods and landslides.
A recent study in the Himalayas indicate that human-induced climate change has led to accelerated warming of the world’s highest mountain range and the Tibetan Plateau at a rate of 0.2 degrees Celsius per decade during 1951-2014.
High-elevation areas (of altitude greater than 4 kilometres), in particular, underwent amplified warming at a rate of about 0.5 °C per decade. Many areas in the Himalayan region, except the high-elevation Karakoram Himalayas, experienced glacier retreat and significant decline in wintertime snowfall in recent decades.
Future warming in the region, which is projected to be in the range of 2.6-4.6°C by the end of the twenty-first century, will further exacerbate the snowfall and glacier decline, leading to profound hydrological and agricultural impacts in the region.
There are around 900 glaciers in the Uttarakhand section of the Himalayas, covering approximately 2,857 square kilometres of their geographical area.
The receding glaciers in the Uttarakhand Himalayas have left behind enormous sediment in areas above 2,500 metres. These sediments have the potential to generate destructive floods under unusual weather events as the climate becomes warmer.
This calls for not only the routine monitoring of glacial lakes but also incorporating disaster risk assessment in developmental planning.
But ‘development’ seems to be destroying the Dev Bhumi or ‘Land of the Gods’ that is Uttarakhand.
We have to keep in mind that unlike rivers in the plains, Himalayan rivers carry large quantity of sediments generated by glaciers and landslides.
Valleys in the High Himalayas are clogged with enormous quantities of loose sediments, particularly above 2,500 metres. These valleys are ecologically fragile and geologically unstable. Most catastrophic floods in the state in recent times were triggered from these valleys.
There is a scramble on to harness the hydropower potential of Uttarakhand’s rivers at present.
According to the report of the Ravi Chopra Committee on hydropower projects in the Uttarakhand Himalaya, the government plans to harness approximately 27,000 megawatt (MW) of potential hydropower from its rivers by constructing approximately 450 hydropower projects.
Currently, 92 projects with a total installed capacity of approximately 3,624 MW have been commissioned and approximately 38 projects are under construction.
If we look into the nature of distribution of the proposed hydropower projects in Uttarakhand, nearly 22 are planned above an elevation of 3,000 metres in paraglacial zones (areas vacated by the glaciers).
Forty-four are between 3,000 and 2,500 metres (between the paraglacial and winter snow line zones), whereas 54 are proposed between 2,500 and 2,000 metres (around the zone of the winter snow line).
This implies that the projects would largely populate the High Himalayan region dominated by areas that were vacated by the glaciers in the recent geological past.
The Uttarakhand Himalayas are inherently vulnerable due to the presence of weak rocks. Add anthropogenic intervention (various developmental schemes) that ignores scientific considerations and you have the perfect recipe for disaster.
With no long-term strategy for environmental conservation of the vulnerable watershed areas, any developmental planning is likely to fall short of anticipated expectations.
Our apathy towards the fragility of the terrain can be gauged by the fact that even after witnessing two earthquakes and knowing well that Uttarakhand lies in the central seismic gap, we rarely bother to generate a high-resolution database on earthquake-prone watersheds.
The sudden collapse of a mountain front like Bhenti in the Madhyamaheswari valley and the collapse of Varnawat Paravat in Uttarkashi are still enigmas.
There are innumerable landslides which are chronic in nature and are in the proximity of river gorges. These can obstruct rivers at any time and cause flash floods like the 1970s Alaknanda or 1978 Bhagirathi floods.
We certainly require clean energy and must harness the hydropower potential of the Himalayan rivers for the economic growth of the nation. However, at the same time, we cannot ignore the geological and geomorphological boundary condition along with the protection of unique biodiversity of the region.
Navin Juyal was formerly with Physical Research Laboratory, Ahmedabad
Views expressed are the author’s own and don’t necessarily reflect those of Down To Earth
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