Natural refilling of deep aquifers is a slow process because ground
water moves slowly through the unsaturated zone and the aquifer.
The rate of recharge is also an important consideration.
It has been estimated, for example, that if the aquifer that
underlies the High Plains of Texas and New Mexico—an area of
slight precipitation—was emptied, it would take centuries to refill
the aquifer at the present small rate of replenishment. In contrast,
a shallow aquifer in an area of substantial precipitation such as
those in the coastal plain in south Georgia, USA, may be
replenished almost