UPSC Mains 2023 GS3 Q7: model answer
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.
What the question wants
Causes of dam failure and two real examples.
How to structure it
Intro: India has over 5,000 large dams, many over 50 years old. Body: (1) Causes: overtopping from extreme floods and poor spillways, seepage and piping, structural defects, foundation failure, earthquakes, poor maintenance and ageing, operational errors, landslides into reservoirs, GLOFs; (2) Examples: Machchhu-II, Morbi (1979); Banqiao, China (1975); Teesta III/Chungthang (2023), Derna, Libya (2023). Conclusion: Dam Safety Act 2021, DRIP.
- 1(1) Causes: overtopping from extreme floods and poor spillways, seepage and piping, structural defects, foundation failure, earthquakes, poor maintenance and ageing, operational errors, landslides into reservoirs, GLOFs
- 2(2) Examples: Machchhu-II, Morbi (1979)
- 3Banqiao, China (1975)
- 4Teesta III/Chungthang (2023), Derna, Libya (2023)
Model answer
India has over 6,000 large dams, and many are more than 50 years old. A failure releases a wall of water on people downstream.
- Overtopping in extreme floods
- Seepage and piping
- Foundation and design defects
- Earthquakes
- Ageing and poor maintenance
- Glacial lake outbursts
Causes of dam failure
- Overtopping: extreme floods exceed spillway capacity, especially in earthen dams.
- Seepage and piping: water leaking through the body or foundation washes out soil.
- Structural and foundation defects: poor design, materials or weak rock.
- Earthquakes causing cracks or liquefaction.
- Ageing and poor maintenance: silting, jammed gates, cracks left unrepaired.
- Operational errors: late or sudden release of water.
- Glacial lake outbursts and landslides in mountain areas.
Examples
- Machchhu-II dam, Morbi, Gujarat (1979): heavy rain overtopped the earthen dam; thousands died.
- Teesta III dam, Chungthang, Sikkim (October 2023): a glacial lake outburst from South Lhonak Lake destroyed the dam.
- Also Derna, Libya (2023), where Storm Daniel broke two dams.
The Dam Safety Act, 2021 and the Dam Rehabilitation and Improvement Project (DRIP) aim at regular inspection, emergency plans and early warning.
Keywords, cases and data to drop in
overtopping piping Machchhu-II South Lhonak GLOF Dam Safety Act 2021
Where most answers lose marks
- No examples or wrong examples.
- Only natural causes.
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Question text as printed in the official UPSC question paper: https://www.upsc.gov.in/sites/default/files/QP-CSM-23-GENERAL-STUDIES-PAPER-III-180923.pdf The model answer is original Battle IAS work; use it to learn structure, not to memorise.