2023 · GS Paper 3 · Q7 · 10 marks
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.
In short
Dams fail mainly through overtopping by floods beyond spillway capacity, seepage and piping, ageing and design lapses, and external shocks such as earthquakes or glacial lake outbursts. Morbi's Machchhu-II (1979) and Libya's Derna dams (2023) both collapsed when extreme storms met structures that could not pass the flood.
Model answer
Ghissu Editorial · Verified 4 Oct 2026 · 280 words
Hydrological overtopping
Inflows beyond the design flood overtop undersized spillways; earthen dams cannot survive it, as Andhra Pradesh's Annamayya project showed in November 2021.
Seepage and piping
Water tunnelling through the body or foundation carries soil away, which destroyed the Teton Dam (USA, 1976) on first filling.
Ageing and design lapses
Silt, cracks and unrepaired gates erode margins; the National Dam Safety Authority blamed design and quality for the 2023 sinking of the Medigadda barrage piers.
External shocks
Earthquakes and glacial lake outbursts can overwhelm a sound dam, as South Lhonak swept away Teesta III's Chungthang dam in October 2023.
Machchhu-II, Morbi (1979)
On 11 August 1979, inflows beyond spillway capacity and gates that could not be fully opened overtopped the earthen embankments, killing an estimated 1,800 to 25,000 people.
Derna, Libya (2023)
Storm Daniel burst two ageing, poorly maintained earth-fill dams in September 2023, and the surge killed close to 4,000 people by confirmed count.
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Question from the official UPSC Civil Services (Main) Examination 2023 paper. Answer written by Ghissu's engine and checked against our editorial standards. Found an error? Tell us and we correct it within 48 hours.