Tarbuck Ch. 4, pgs. Groundwater comes from precipitation that has percolated downward from the surface through the zone of aeration to a zone of saturation where all the pores and cracks in the bedrock are filled with water. The top of the zone of saturation is known as the water table .
Water tables are higher beneath hills and slope down to feed streams and lakes.
Groundwater is the base flow for streams and base flow keeps streams flowing between rains. In the following diagram, identify the zone of aeration, zone of saturation, soil water belt, and water table. Label the arrows to show the processes that take place once precipitation has fallen on the land. A water-bearing rock layer is known as an aquifer . Impermeable rocks such as clay and shale do not allow the passage of water.