the zone immediately below the land surface where the pores contain both water and air, but are totally saturated with water. Plant roots can capture the moisture passing through this zone, but it cannot provide water for wells. Also know as the unsaturated zone
Cone of depression
the zone around a welll in an unconfined aquifer that is normally saturated, but become unsaturated as a well is pumped, leaving an area where the water table dips down to form a cone shape. The shape of the cone is influenced by porosity and the water yield or pumping rate of the well.
Geologic material with little or no permeability or hydraulic conductivity. water does not pass through this layer or the rate of movement is extremely slow.
the loss of water from surface ater reservoirs or groundwater aquifers at a rate greater than that of recharge.
an outflow of water from a stream, pipe, groundwater aquifer, or watershed; the opposite of recharge
the time required for a volume of groundwater to move between points. Typically groundwater moves very slowly- sometimes only inches per year