An aquifer is a subsurface (or underground) geologic formation that can store and supply water at an appreciable rate. The recharge zone of an aquifer is defined as the region or area that will drain into the particular aquifer. The recharge zone will collect all the rainwater and any other additions to it and funnel it into the aquifer. Any pollution of the recharge zone will thus affect the water quality of the aquifer. Consider agricultural field in the recharge zone that are using fertilizers. All the excess fertilizers will be removed by the rainwater (and/or irrigation water) and will reach the aquifer. Any excess sewage or industrial waste discharge from the neighboring cities will also reach the aquifer. In fact, if the river and aquifer are interconnected (As is the scenario many time), any pollution of the river (by city drains, solid waste, industrial discharges, etc.) will ultimately reach the aquifer. And hence any pollution in the region will adversely affect the aquifer recharge zone and the aquifer.
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