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:

The correct answer is B.

• Statement 2 is correct. Riverbed sand acts as a natural filter. Once it is dug out, pollutants and contaminants seep more easily into the aquifer below, degrading groundwater quality.
• Statement 3 is correct. Removing sand lowers the riverbed level and the adjoining water table, which dries up nearby wells and hand pumps.
• Statement 1 is wrong. Sand mining tends to do the opposite. Lower river levels and reduced freshwater flow allow saline water to move inland in deltas and coastal stretches, so salinity rises rather than falls.

The core concept is the riverbed as a hydrological system: sand stores and filters water, and extraction disturbs that balance. The MoEFCC's Sustainable Sand Mining Management Guidelines (2016), later supplemented by enforcement and monitoring guidelines (2020), were issued to regulate this. The issue fits Mains GS-III on environment and water resources.

Trap: Aspirants assume that removing material from a river must dilute dissolved salts and pick option A or D. Think about what the riverbed sand does for the water flowing over it, not just about the sand itself.