Infiltration is the process by which water on the ground surface enters the
soil.
Infiltration rate in
soil science is a measure of the rate at which soil is able to absorb
rainfall or
irrigation. It is measured in inches per hour or millimeters per hour. The rate decreases as the soil becomes saturated. If the precipitation rate exceeds the infiltration rate,
runoff will usually occur unless there is some physical barrier. It is related to the saturated
hydraulic conductivity of the near-surface soil. The rate of infiltration can be measured using an
infiltrometer.