Which of the following is a negative effect of groundwater or aquifer depletion?

Groundwater or aquifer depletion can lead to significant environmental issues, one of which is the possible saltwater contamination of the water supply. This occurs particularly in coastal areas where the depletion of freshwater from aquifers reduces the hydrostatic pressure that keeps saltwater at bay. As freshwater is withdrawn for agricultural, municipal, or industrial use, there may not be enough pressure in the aquifer to prevent saltwater from encroaching into the freshwater supply. This can result in a mixture of saltwater with freshwater, making it unsuitable for drinking and irrigation and posing a serious threat to local ecosystems and agricultural practices.

The other options do not accurately represent the consequences of aquifer depletion. A decrease in water temperature, increased biodiversity, or improved water quality do not typically occur as a result of reduced groundwater levels; instead, they may reflect conditions that arise from sufficient aquifer replenishment or management practices aimed at conserving water resources. Thus, the possibility of saltwater contamination stands out as a definitive negative effect of groundwater or aquifer depletion.