Social Science (087) — AI-generated practice question

Dams are built to store and regulate river water, but they can ironically cause floods due to sedimentation in the reservoir. Over time, sediment accumulates at the bottom of the reservoir, reducing its water-holding capacity. When excessive rainfall occurs, the reduced reservoir cannot hold the extra water. The dam gates must be opened suddenly, releasing large volumes of water downstream and causing floods. As the textbook states, "dams that were constructed to control floods have triggered floods due to sedimentation in the reservoir." Moreover, big dams have mostly been unsuccessful in controlling floods during excessive rainfall.

Source: Water Resources, Chapter 3 (Multi-purpose River Projects and Integrated Water Resources Management)

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• The key cause is sedimentation reducing reservoir capacity — this is the direct answer examiners expect.
• Quote or paraphrase the textbook line about dams triggering floods — it shows you have read the source.
• For 3 marks: name the problem (sedimentation), explain the mechanism (reduced capacity), and state the consequence (uncontrolled release → floods). Three clear points = 3 marks.