From UPSC perspective, the following things are important :
Prelims level : Main Central Thrust
Mains level : Paper 3- Rethinking the hydroelectric projects in Himalayas
The affidavit filed recently by the Ministry of Environment, Forest and Climate Change (MoEFCC) in an ongoing matter in the Supreme Court of India has recommended the construction of seven partially constructed hydroelectric projects in the Uttarakhand Himalaya.
- After the Kedarnath tragedy of 2013, an expert body (EB-I) was constituted to investigate whether the hydro-power projects in the State of Uttarakhand was linked to the disaster.
- In its findings, EB-I said there was a “direct and indirect impact” of these dams in aggravating the disaster.
- The Ministry formed another expert body (EB-II; B.P. Das committee) whose mandate has been to pave the way for all projects through some design change modifications
- This affidavit, dated August 17, reveals that the government is inclined towards construction of 26 other projects, as in the recommendation of the expert body (EB-II; B.P. Das committee).
- Ministry’s own observations and admissions given in its earlier affidavit dated May 5, 2014 admitted that hydroelectric projects did aggravate the 2013 flood.
- Sustainability: The sustainability of the dams in the long term is highly questionable as hydropower solely relies on the excess availability of water.
- Temperatures across the region are projected to rise by about 1°C to 2°C on average by 2050.
- Retreating glaciers and the alternating phases of floods and drought will impact the seasonal flows of rivers.
- Sediment hotspots: The most crucial aspect is the existence of sediment hotspot paraglacial zones, which at the time of a cloud burst, contribute huge amounts of debris and silt in the river.
- The flash floods in these Himalayan valleys do not carry water alone; they also carry a massive quantity of debris.
- This was pointed out by EB-II alongside its recommendation not build any projects beyond 2,000 metres or north of the MCT, or the Main Central Thrust (it is a major geological fault).
- Externalities: Though hydropower is renewable source, there are contentious externalities associated with the construction of dams such as social displacement, ecological impacts, environmental and technological risks.
- Climate change: these projects exacerbate ecological vulnerability, in a region that is already in a precarious state.
- The intense anthropogenic activities associated with the proliferation of hydroelectric projects in these precarious regions accelerate the intensity of flash floods, avalanches, and landslides.
- Failure of mountain slopes: The construction and maintenance of an extensive network of underground tunnels carrying water to the powerhouses contribute to the failure of mountain slopes.
- Aggravating the disaster: The Rishi Ganga tragedy and the disasters of 2012 (flashfloods), 2013 are examples of how hydroelectric projects which come in the way of high-velocity flows aggravate a disaster and should be treated as a warning against such projects.
Considering the environmental and cultural significance of these areas, it is imperative that the Government refrains from the construction of hydroelectric projects and declares the upper reaches of all the headstreams of the Ganga as eco-sensitive zones. It must allow the river to flow unfettered and free.
Back2Basics: Main Central Thrust (MCT)
- The Main Central Thrust is a major geological fault where the Indian Plate has pushed under the Eurasian Plate along the Himalaya.
- The fault slopes down to the north and is exposed on the surface in a NW-SE direction (strike).
- It is a thrust fault that continues along 2200 km of the Himalaya mountain belt