GEOLOGY

Detailed explanation-1: -An aquifer is an underground layer of water-bearing rock. Excavation and mining, excessive use of fertilisers and septic tank leakage can contaminate underground water.

Detailed explanation-2: -Groundwater sources continue to face many threats from the effects of agricultural intensification, urbanisation and population growth. When carrying out a global groundwater quality assessment, three major threats include anthropogenic contaminants, naturally occurring contaminants and climate change.

Detailed explanation-3: -Saltwater intrusion can occur in aquifers near coastlines, when fresh groundwater in the aquifer is displaced by salt water. Coastline aquifers become more vulnerable to saltwater intrusion when freshwater recharge rates are low or withdrawal rates are high.

Detailed explanation-4: -drying up of wells. reduction of water in streams and lakes. deterioration of water quality. increased pumping costs. land subsidence.