UPSC Prelims 2018 Question:

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

1. Decreased salinity in the river
2. Pollution of groundwater
3. Lowering of the water-table
   
   

Select the correct answer using the code given below:

Explanation:

• "Sand mining" is a practice that is used to extract sand from various environments, such as beaches, inland dunes and dredged from ocean beds, and river beds of deltaic regions.
  
  
• Consequences of heavy sand mining in river beds are as follows:
  • Depletion of sand in the streambed causes the deepening of rivers and the enlargement of river mouths and coastal inlets. It leads to saline-water intrusion and increased salinity in the river. So, point 1 is not correct.
  • Mining and dredging activities lead to poorly planned stockpiling and uncontrolled dumping of chemical/fuel spills will cause reduced water quality for downstream users. This will further lead to pollution of groundwater. So, point 2 is correct.
  • Sand aquifer helps in recharging the water table. Sand mining causes sinking of water tables in the nearby areas. Riverbed becomes dry due to exposure to solar radiation which decreases the surface and groundwater. So, point 3 is correct.
    
    

Therefore, option (2) is the correct answer.

Subject: Environment | Pollution