The question “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." was asked in the Mains 2023 GS Paper 3. Let us look at the model answer to this question.
Answer: Dam failure refers to the catastrophic breach of a dam structure which may result from diverse natural and anthropogenic causes. Its impact can be severe and far reaching, affecting both human lives, infrastructure and the environment. India has 5745 numbers of dams (5334 are completed and 411 are under construction). India is ranked third in the world in terms of building large dams.
Causes of Dam Failures
- Ageing Dams : According to a UN report over 1,000 large dams in India will be roughly 50 years old in 2025 and such ageing embankments across the world pose a growing threat.
- Structural failure: Inadequate design, construction materials, or maintenance can lead to dam collapse.
- Extreme weather events: Heavy rainfall or flooding can cause dam failures, as seen in the 1979 Machchhu dam failure.
- Geological instability: Landslides or tectonic activity can compromise dam structures.
- Overtopping: Excessive water spilling over the top of a dam, often a precursor to dam failure.
- Foundation Problems: Weak or unstable foundation soils beneath the dam.
- Operational Failures: Improper operation of the dam, including inadequate release of water during periods of high inflow.
Examples of Large Dam failures
- 1979 Machchhu dam failure: Excessive rain and flooding led to the disintegration of the earthen walls of the Machchhu-2 dam in Gujarat, causing immense damage and loss of life.
- Banqiao Dam Failure (1975): The Banqiao Dam, part of a system of dams in Henan, China, experienced a catastrophic failure in 1975 during Typhoon Nina. The dam received excessive rainfall, and its spillways were not able to handle the inflow. The dam eventually overtopped and breached, leading to a series of downstream dam failures.
India’ Dam Safety Act 2021, and Dam Safety Rehabilitation and Improvement Project (DRIP) provides for robust maintenance, monitoring, community preparedness to prevent catastrophic dam failures in India.