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 :

Reference [1] describes how removing river sand deepens channels, alters beds, and affects local groundwater — the primary pathway by which sand mining could change river water characteristics.

High-yield for environment and river-management questions: explains direct physical impacts of extraction on river form, habitat and groundwater availability. Links to topics such as river erosion, water security, and regulatory policy; useful for essay and mains answers on anthropogenic impacts on fluvial systems.

References [9] and [5] state that freshwater flow from rivers lowers surface salinity in coastal waters and affects horizontal salinity distribution.

Essential for questions on coastal processes, estuaries and river-sea interactions: shows how river discharge influences salinity gradients, ecosystem health and coastal circulation. Helps answer mains questions on estuarine dynamics, impacts of altered river flow, and linkages between inland activities and coastal environments.

References [10] and [4] list evaporation, precipitation, and ocean currents as main controls on surface salinity — framing other drivers besides river inflow.

Core physical geography concept: knowing these controls allows candidates to evaluate multiple mechanisms that change salinity (not only river flow). Useful across GS papers for questions on climate, oceanography and environmental change; enables balanced answers explaining competing influences.

Reference [1] identifies riverbed sand as a link between the flowing river and the water table, making its removal relevant to groundwater quantity and quality.

High-yield for questions on surface–groundwater interactions and impacts of riverbed interventions. Links hydrology, riverine geomorphology, and resource management topics; useful for case-based questions on sand mining and aquifer health. Learn by mapping physical roles of river sediments to groundwater recharge and storage.

References [2] and [5] identify mining activities and mining wastes (heavy metals, inorganic compounds) as direct sources of groundwater pollution.

Essential for environment and pollution questions: shows a generic mechanism (waste discharge, leaching) that applies across mining types including sand extraction. Helps answer cause–effect and mitigation questions; connects to pollution control laws and water management strategies in UPSC papers.

Evidence shows sand mining causes groundwater depletion ([1]) while other mining sources cause contamination ([2],[5],[4]). Distinguishing both outcomes is necessary to assess impacts.

Crucial for balanced answers: candidates must separate quantity impacts (depletion, altered recharge) from quality impacts (pollutants, heavy metals). This enables nuanced policy recommendations and links to water law, disaster management, and sustainable extraction topics.

Reference [1] identifies riverbed sand as a link between the flowing river and the water table and as part of the aquifer; removing it disrupts storage and connectivity.

High-yield for environment and physical geography questions on groundwater recharge, river systems and anthropogenic impacts. Helps answer questions on sand mining, groundwater policy, and riverine ecology by linking geomorphology to hydrology. Master by studying aquifer types, river–groundwater interactions, and case examples.