Dangers of Large Dams in India

Dangers of Large Dams in India

Context: We discuss the dangers that large dams possess in India especially in context with recent collapse of Chungthang dam in Sikkim due to GLOF from South Lhonak lake.

Large Dams in India:
• India has 5264 operational large dams with Maharashtra (2354), MP (906), Gujarat (632), Chattisgarh (258) and Karnataka (231)
• India is the 3rd largest dam-owning nation in the world.

Issues with Large Dams
• Ageing Large dams – Many large dams were built half a century ago and their construction become weak as construction materials such as concrete and steel deteriorate due to abrasion from waves, silt, sand, and gravel. Around 80% of large dams in India are 25 years old.
• Dam-induced earthquakes - Stresses generated by the water load can lead to earthquakes.
• Loss of Life - Rapid release of water during a dam failure can result in a significant loss of lives, especially in downstream areas. Example, Chungthang dam failure, Macchu (Morbi) in 1979
• Sedimentation – The sediment that accumulates behind the dams reduces the water storage capacity of the reservoir, leading to reduced power generation, irrigation, and drinking water supply.
• Environmental issues – Loss of wildlife habitat, alteration of river ecosystems and changes in hydroglogy of the area.
• Social and cultural impact – Displacement of people (primarily tribal population) and loss of culturally relevant sites (Sacred groves, historical venues)

What are the initiatives taken for Large dams in India?
• Dam Safety act, 2021 – It has provisions for comprehensive dam safety evaluation of all the specified dams. The evaluation is carried out by independent panel of experts.
• Central water commission (CWC) compiles and maintains nation-wide register of large dams.
• Dam Rehabilitation and Improvement Project (DRIP) – It aims to improve the safety and operational performance of selected existing dams.
• CWC has also developed web based asset management tools like DHARMA (Dam Health and Rehabilitation Monitoring System) to monitor the health of dams.

What are the alternatives of Large dams?
• Sub-surface dams - Unlike a surface dam, water loss by evaporation is minimal in underground dams.
• Usage of traditional water storage methods– tanks and canals, with the usage of micro irrigation techniques, to reduce requirements of water for irrigation.
• Focus on alternative sources of renewable energy– solar and wind power
• Reuse of water- use of recycled sewage water for irrigation and industrial purposes. This reduces the need for dam construction.
• Instream Energy Generation (IEG) - This uses clusters of small turbines, enabling fish and sediments to pass freely while generating power.