UPSC Prelims Practice Questions — Dams make rivers warmer downstream: satellite data

Q1. The 2026 Science Advances study on dam-induced river warming used satellite thermal-infrared data spanning 2013–2024. How many large dams across the United States did it assess for downstream thermal alteration?

  • A. 71
  • B. 91
  • C. 287
  • D. 600

Q2. Satellite thermal-infrared imagery of the kind used to take 'the temperature of rivers from space' is supplied chiefly by the Landsat series, which is jointly operated by the U.S. Geological Survey and which other agency?

  • A. NOAA
  • B. NASA
  • C. EPA
  • D. USDA

Q3. In India, surveillance and safety regulation of large ('specified') storage dams — the reservoir-type dams linked to the greatest downstream thermal alteration — is vested in the National Dam Safety Authority, which functions under which Union ministry?

  • A. Ministry of Environment, Forest and Climate Change
  • B. Ministry of Power
  • C. Ministry of Jal Shakti
  • D. Ministry of Earth Sciences

Q4. According to the 2026 satellite study, the overwhelming majority (about 91%) of the most extreme downstream temperature shifts (≥±4°C) were associated with which single category of dam?

  • A. Run-of-river dams
  • B. Dams with (storage) reservoirs
  • C. Diversion weirs
  • D. Tidal barrages

Q5. In India, the principal statute empowering pollution control boards to regulate discharge of heated effluents into rivers (thermal pollution) is:

  • A. The Environment (Protection) Act, 1986
  • B. The Water (Prevention and Control of Pollution) Act, 1974
  • C. The River Boards Act, 1956
  • D. The Wildlife (Protection) Act, 1972

Q6. In the context of rivers, 'thermal pollution' is most precisely defined as:

  • A. Contamination of water by toxic heavy metals from industrial effluents
  • B. A human-caused rise (or fall) in the natural temperature of a water body — e.g. from discharge of heated water or altered dam releases — that degrades its ecological quality
  • C. Nutrient enrichment of water that triggers algal blooms and eutrophication
  • D. Accumulation of thermoplastic microplastics in riverbed sediments

Q7. The 2026 assessment is described as the first study to characterise dam-induced river thermal alteration at a near-continental scale. Which single data source made this basin-wide, multi-year approach possible in place of site-specific field sampling?

  • A. Automated in-stream thermistor networks
  • B. Satellite thermal-infrared (Earth-observation) imagery
  • C. Airborne LiDAR surveys
  • D. Crowd-sourced angler temperature logs

Q8. The Hoover Dam, a concrete arch-gravity dam on the Colorado River impounding Lake Mead, was completed in which year?

  • A. 1931
  • B. 1936
  • C. 1941
  • D. 1963