Which of the following is/are possible consequence/s of heavy sand mining in river beds?Decreased sa

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UPSC Prelims is a competitive examination conducted in India. This question is from the 2018 UPSC Prelims Environment & Ecology paper.

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To prepare for UPSC Prelims Environment & Ecology, practice previous year questions (PYQs), understand concepts thoroughly, and solve mock tests regularly. This 2018 question covers Soil & Land Degradation – Desertification & Remediation topic.

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This UPSC Prelims 2018 Environment & Ecology question has a medium difficulty level and is marked as an important question.

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Question

Which of the following is/are possible consequence/s of heavy sand mining in river beds?Decreased salinity in the riverPollution of groundwaterLowering of the water-tableSelect the correct answer using the code given below:

Accepted Answer

Correct Answer: B — 2 and 3 onlyStep-by-step Solution:Statement 1 — Decreased salinity in the river: This is incorrect. Heavy sand mining actually leads to increased salinity in rivers — not decreased salinity. When river beds are deepened by sand mining, it causes saltwater intrusion from the sea (in coastal rivers), making the water more saline. Additionally, lowering the riverbed causes the river to draw in saline groundwater. Decreased salinity is not a consequence of sand mining. ✗Statement 2 — Pollution of groundwater: This is correct. Sand mining operations often involve heavy machinery, fuel spills, and disturbance of riverbed sediments that contain pollutants. The removal of the natural sand-aquifer filter allows pollutants to percolate more easily into groundwater. Additionally, the removal of the riverbed's natural filtration layer can allow surface pollutants to contaminate underlying aquifers more readily. ✓Statement 3 — Lowering of the water-table: This is correct. River sand acts as a natural aquifer that stores and slowly releases water, recharging the water table in surrounding areas. Excessive sand removal reduces the sand's water-holding capacity, disrupting groundwater recharge. This causes water tables to drop in areas adjacent to heavily mined rivers, leaving drinking water wells dry — a severe problem documented in many parts of India (Kerala, Karnataka, Tamil Nadu). ✓Why other options are incorrect:Option A (1 only): Statement 1 is wrong — sand mining increases salinity through saltwater intrusion, not decreases it.Option C (1 and 3 only): Statement 1 is incorrect.Option D (1, 2 and 3): Statement 1 is wrong.Key Concept: Consequences of sand mining: (1) Bank erosion — lowering streambed causes undercutting of banks; (2) Bridge damage — undermines bridge foundations; (3) Saltwater intrusion — increased river salinity near coast; (4) Water table depletion — reduces groundwater recharge; (5) Loss of aquatic habitat — destroys spawning grounds for fish; (6) Increased turbidity — affects water quality downstream; (7) Groundwater pollution — from mining machinery and disturbed sediments. India's Sand Mining Framework (2018) and the Mining Rules under MMDR Act regulate sand mining, but illegal mining remains pervasive. Sand is the second most extracted natural resource after water.

Which of the following is/are possible consequence/s of heavy sand mining in river beds?Decreased salinity in the riverPollution of groundwaterLowering of the water-tableSelect the correct answer using the code given below:

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Which of the following is/are possible consequence/s of heavy sand mining in river beds?Decreased salinity in the riverPollution of groundwaterLowering of the water-tableSelect the correct answer using the code given below:

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More Questions from Soil & Land Degradation – Desertification & Remediation

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