Social Science (087) — AI-generated practice question

Large dams are built to control floods by storing excess river water in reservoirs. However, sedimentation causes this mechanism to backfire. Over time, silt and sediment accumulate at the bottom of the reservoir, reducing its water-holding capacity. When excessive rainfall occurs, the reduced reservoir cannot hold the surplus water. Dam operators are then forced to release large volumes of water suddenly, which floods the downstream areas. Additionally, big dams have mostly been unsuccessful in controlling floods during periods of excessive rainfall.

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

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• The key term examiners expect is sedimentation — always use it.
• The two-step logic is essential: sedimentation → reduced capacity → forced sudden release → floods downstream.
• The textbook directly states: "dams constructed to control floods have triggered floods due to sedimentation in the reservoir" — paraphrase this directly.
• Avoid writing about other dam disadvantages (displacement, earthquakes, etc.) — they are off-topic for this specific question.