GS3/GS1 Paper
Syllabus: Disaster management/ Geography/ Hydropower
Context: The article highlights the dangers of large dams in India, especially in the Himalayas. It discusses the recent collapse of the Chungthang dam in Sikkim due to the eruption of South Lhonak Lake.
Status of Dam in India:
India is the 3rd largest dam-owning nation in the world. There are around 5,700 large dams in the country, of which about 80% are over 25 years old.
Benefits of dams
- Generation of hydroelectric power– Dams provide hydropower, which contributes 12% to India’s total energy
- Irrigation– Between 1950- 2000, dams contributed to 35% of the total irrigated land, and increased food grain production by 25%.
- Provision of water to households and industries– The regulated flow of water dilutes harmful dissolved substances in river waters during lean periods by supplementing low inflows and maintaining the quality of water within safe limits.
- Ex- Tansa dam supplies water to Mumbai city.
- Drought mitigation– dams store water that can be used when rainfall is below normal limits. Ex- Sardar Sarovar dam in Gujrat.
- Flood prevention– dams check the flow of water and prevent flooding in low-lying areas, protecting lives and property.
- Inland navigation– provide navigation channels throughout the year, due to controlled levels of water.
- Recreation– dams offer recreational activities such as boating, fishing and swimming.
| Impact | Description | Example |
| Dam-induced earthquakes | Stresses generated by the water load can lead to earthquakes. | Koyna earthquake – Hoover Dam, USA |
| Loss of life
|
Rapid release of water during a dam failure can result in a significant loss of lives, especially in downstream areas. | Chungthang Dam failure in Sikkim (Recent); Machhu Dam, Morbi, Gujarat (1979) |
| Damage to the ecosystem | Dams alter migratory routes of aquatic life, leading to the loss of forest land and wetlands. | Narmada Bachao Andolan; Hirakud dam construction |
| Displacement of people | Dam construction displaces local populations and causes the loss of indigenous cultures. | Hirakud dam construction |
| Sedimentation | Sedimentation reduces the storage capacity of dams and requires frequent maintenance. | |
| Soil erosion | Dams can cause erosion in surrounding areas. | China’s Three Gorges Dam |
| Disasters due to lack of coordination | Lack of coordination between authorities can lead to disasters, such as floods due to the release of dam water. | Kerala floods 2018 |
| High cost | Dams are expensive to build and maintain. | Sardar Sarovar dam |
Various causes of dam failures:
- Seismic damage: Earthquakes can subject dams to strong ground shaking, which may lead to structural damage or foundation failure.
- Kobe Earthquake, Japan (1995): While not a dam failure, the Kobe Earthquake in Japan caused damage to dams and their components.
- Erosion and piping: Erosion occurs when the flow of water erodes the soil or rock supporting the dam’s structure. Piping, a related issue, involves the internal erosion of dam materials, creating channels through which water can escape.
- Extreme weather events: Intense and prolonged rainfall, hurricanes, or typhoons can result in dam failures due to increased water inflow, exceeding the dam’s storage capacity.
- Kedarnath Floods, India (2013): While not a traditional dam failure, the catastrophic flooding in the Kedarnath region of Uttarakhand, India, in 2013, was triggered by heavy rainfall and the sudden release of water from a glacial lake.
- Glacial lake outburst flood (GLOF): In mountainous regions with glaciers, the sudden release of meltwater from a glacier-dammed lake can trigger a GLOF. These events can lead to massive floods downstream, posing a significant threat to communities and infrastructure.
- Human factors: This includes poor operational decisions, inadequate maintenance, conflict and war can contribute to dam failures.
- Design limitations: Flaws in the original design, including inadequate spillways, improper materials, or underestimated water flow calculations can lead to structural weaknesses.
Two examples of large dam failures:
- The recent Derna dam collapse Failure of two roughly 75 and 45-meter tall dams following heavy rain from Storm Daniel against the backdrop of the Libyan civil war resulting in the city of Derna.
- Kakhovka Dam failure: The dam in Ukraine was breached in June 2023, causing extensive flooding along the lower Dnieper River. Many experts have concluded that Russian forces likely blew up a segment of the dam to hinder the Ukrainian counter-offensive.
While dams contribute extensively towards water management, there are significant risks associated with dams, on account of their ageing and poor management.
Measures taken to ensure dam safety:
| Measure | Description |
| Dam Safety Act 2021 | Aims at surveillance, inspection, operation, and maintenance of specified dams (dams with height over 15 meters or dams between 10-15 meters with certain design and structural conditions) |
| Constitutes 2 national bodies: The National Committee on Dam Safety (Formulation of policies and recommendations for dam safety) and the National Dam Safety Authority (implementation of policies of the National Committee). | |
| Constitutes 2 state bodies: State Dam Safety Organization (for inspection and monitoring of dams) and State Committee on Dam Safety (for supervision of dam rehabilitation programs). | |
| Provides for inspection of specified dams twice a year (pre and post-monsoon) | |
| Includes an emergency action plan in case of disasters | |
| Lists the responsibilities of dam owners and ensures that these responsibilities are carried out through penal measures. | |
| Dam Rehabilitation and Improvement Project (DRIP) | Implemented by the Central Water Commission with assistance from the World Bank and the Asian Infrastructure Investment Bank |
| Aims to improve the safety and operational performance of selected existing dams. | |
| Includes DHARMA (Dam Health and Rehabilitation Monitoring System) to monitor the health of dams. |
Mega dams are large structures over 15 metres in height generating over 400 megawatts of power on average. They cause severe damage to ecosystems and lead to the displacement of indigenous populations.
Alternatives to mega-dams
- Construction of smaller sub-surface dams. Ex- Japan. They reduce evaporation losses and cause less damage to the environment.
- Improving the capacity of existing dams, instead of the construction of new dams- causes less ecological damage.
- 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.
Conclusion:
Dams are the lifeline of Indian agriculture and India’s water security. Dam management should be done in a sustainable way to ensure that they do more good than harm.
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Mains Links:
Dam failures are always catastrophic, especially on the downstream side, resulting in a colossal loss of life and property. Analyze the various causes of dam failures. Give two examples of large dam failures. (UPSC 2023)
