How does water infiltrate from the land surface into soil?

In hydrologic sciences, infiltration is the process by which water from precipitation or snowmelt enters the soil profile and moves downward. This movement is governed by several key factors:12

• Infiltration Capacity: This represents the maximum rate at which a specific soil can absorb water. If the intensity of rainfall exceeds this capacity, the excess water typically becomes surface runoff once surface depressions are filled.312
• Soil Characteristics: The physical properties of the soil, such as porosity and permeability, are critical. Coarser soils generally allow for faster infiltration, while finer-textured soils—particularly those rich in clay—may experience reduced rates as colloidal particles swell upon wetting or as pores become clogged by surface particles.41
• Surface Conditions: The presence of vegetation, surface seals, or large channels and cracks can significantly influence how easily water enters the ground.2

Infiltration rates are typically highest at the start of a rainfall event on dry soil and decrease over time as the soil becomes saturated. Once inside, water may be stored as soil moisture, taken up by plant roots, or percolate deeper due to gravity to replenish groundwater supplies.15