Which of the following is/are the possible consequence/s of heavy sand mining in riverbeds ?
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 :
Which of the following is/are the possible consequence/s of heavy sand mining in riverbeds ?
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 :
Answer:
(b)
Core Books/NCERT
The removal of sand from the river bed increases the velocity of the flowing water, with the distorted flow-regime eventually eroding the river banks. Sand acts like a sponge, which helps in recharging the water table; its progressive depletion in the river is accompanied by declining water tables in the nearby areas. Depletion of sand in the stream bed causes the deepening of rivers and estuaries, and the enlargement of river mouths and coastal inlets. It leads to saline-water intrusion. Sand acts as an efficient filter for various pollutants and thus maintains the quality of water in rivers and other aquatic ecosystems.