Groundwater Recharge (in the hydrogeological sense)

The volume recharging a groundwater body over a given period. Rainfall is the main source of groundwater recharge (see effective infiltration).

An unconfined body of groundwater recharges quite quickly during each precipitation event. The rise in water levels and precipitation events can be observed on a piezometric graph. Groundwater bodies recharge once the soil has become saturated, with the rainwater directly infiltrating at outcrop area level.

Recharging a confined aquifer is, however, a much slower process. Precipitation events are either not visible or barely visible on the piezometric graph. The rise in water levels depends on the distance of the outcrop (water takes longer to move through the soil and rocks), and local transfers between bodies of groundwater, amongst other factors.