Q. 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.
Question from UPSC Mains 2023 GS3 Paper
Model Answer:
India operates over 5,300 large dams. Ageing infrastructure combined with climate extremes makes dam failures severe cascading disasters for downstream communities.
Causes of Dam Failures
- Hydrological Constraints: Sudden flash floods, Glacial Lake Outburst Floods (GLOFs), or cloudbursts exceeding the designed spillway capacity, causing overtopping.
- Structural Deterioration: Internal erosion (piping), foundation seepage, and material decay in ageing infrastructure (over 200 Indian dams are 100+ years old).
- Seismological Vulnerability: Earthquake-induced liquefaction, landslides, or structural cracking in highly active seismic zones (e.g., Himalayan river basins).
- Operational & Maintenance Lapses: Delayed gate openings during monsoons, faulty spillway mechanics, and non-adherence to Central Water Commission (CWC) rule curves.
Examples of Large Dam Failures
- Chungthang Dam (Sikkim, 2023): The Teesta Stage III dam was washed away entirely by a massive GLOF originating from South Lhonak Lake, destroying downstream towns.
- Machchhu Dam II (Morbi, Gujarat, 1979): The earthen dam collapsed due to extreme overtopping during unprecedented, continuous rainfall, resulting in thousands of casualties.
Strict enforcement of the Dam Safety Act 2021, structural upgrades via the Dam Rehabilitation and Improvement Project (DRIP), and robust NDMA-guided Early Warning Systems are imperative for downstream resilience.
