qClimate interacts only
with water that is on the surface or in
the soil water zone.
qThe soil water zone
extends downward to the depth penetrated
by the root of the vegetation.
qSoil storage
capacity (field capacity of the soil) is the amount of moisture the soil can hold.
qIf soil water content
increases above the capacity, gravitational
forces carry the water downward to the
water table, where it becomes
groundwater.