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:
A) 1 only B) 2 and 3 only
C) 1 and 3 only D) 1,2 and 3
Explanation : Ans : (B)
Sand Mining and Impact on Environment
Sand Mining is an activity referring to the process of the actual removal of sand from the foreshore including rivers, streams and lakes. Sand is mined from beaches and inland dunes and dredged from ocean beds and river beds.
The effect of mining is compounded by the effect of sea level rise. Any volume of sand exported from streambeds and coastal areas is a loss to the system.
The stream sand mining results in the destruction of aquatic and riparian habitat through large changes in the channel morphology. Impacts include bed degradation, bed coarsening, lowered water tables near the streambed, and channel instability.
Further all species require specific habitat conditions to ensure long term survival. Native species in streams are uniquely adapted to the habitat conditions that existed before humans began large scale alterations.
Factors that increase or decrease sediment supplies often destabilize bed and banks and result in dramatic channel readjustments. For example, human activities that accelerate stream bank erosion, such as riparian forest clearing or in stream mining, cause stream banks to become net sources of sediment that often have severe consequences for aquatic species.
Apart from it, sand mining transforms the riverbeds into large and deep pits; as a result, the groundwater table drops leaving the drinking water wells on the embankments of these rivers dry.
