Which of the following is/are the possible consequence/s of heavy sand mining in riverbeds ?
Consider the following statements:
- Decreased salinity in the river
- Pollution of groundwater
- Lowering of the water-table
Select the correct answer using the code given below:
1 only
2 and 3 only
1 and 3 only
1, 2 and 3
Answer is Wrong!
Answer is Right!
This question was previously asked in
UPSC IAS – 2018
1. **Decreased salinity in the river:** Heavy sand mining typically impacts the physical structure of the riverbed and flow dynamics, and potentially groundwater interaction. It does not directly cause a decrease in salinity in the river water itself. In coastal areas, it might affect the balance between freshwater and saltwater, potentially leading to increased saltwater intrusion rather than decreased salinity in river areas influenced by tides. This statement is incorrect.
2. **Pollution of groundwater:** Sand and gravel in a riverbed act as a natural filter, helping to purify water as it infiltrates into the groundwater system. Heavy sand mining removes this protective layer, making the groundwater aquifer more vulnerable to contamination from surface pollutants (like agricultural runoff, industrial waste, sewage). This statement is correct.
3. **Lowering of the water-table:** Riverbeds are often hydraulically connected to the surrounding groundwater table. Removing large quantities of sand from the riverbed lowers the base level of the river and disrupts this connection. This can lead to a corresponding drop in the groundwater table in adjacent areas, affecting wells and vegetation that rely on shallow groundwater. This statement is correct.