Summary

Infiltration is the process by which water penetrates the soil and enters the unsaturated zone of the soil. If water in a particular region is not given enough opportunity to infiltrate into the soil, it can contribute to water scarcity in that region.

Infiltration is caused by multiple factors including; gravity, capillary forces, adsorption, and osmosis. Many soil characteristics can also play a role in determining the rate at which infiltration occurs.

Precipitation can impact infiltration in many ways. The amount, type, and duration of precipitation all have an impact. Rainfall leads to faster infiltration rates than any other precipitation event, such as snow or sleet. In terms of amount, the more precipitation that occurs, the more infiltration will occur until the ground reaches saturation, at which point the infiltration capacity is reached.

The duration of rainfall impacts the infiltration capacity as well. Initially when the precipitation event first starts the infiltration is occurring rapidly as the soil is unsaturated, but as time continues the infiltration rate slows as the soil becomes more saturated. This relationship between rainfall and infiltration capacity also determines how much runoff will occur. If rainfall occurs at a rate faster than the infiltration capacity runoff will occur.