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 :
Explanation
Statement 1 is Incorrect: Sand mining does not decrease salinity. In coastal and estuarine regions, excessive sand mining can lead to saltwater intrusion from the sea into the river system, which actually increases the salinity of the river water.
Statement 2 is Correct: River sand acts as a natural filter for water percolating through the riverbed. Removing this sand layer reduces the filtration capacity, allowing pollutants, heavy metals, and contaminants to seep more easily into the underlying groundwater aquifers.
Statement 3 is Correct: Heavy sand mining causes riverbed incision (deepening of the river channel). As the riverbed drops, the surrounding groundwater drains into the deepened channel to maintain hydrological equilibrium, leading to a significant lowering of the water table in the adjacent areas.