For infiltration to occur, the land must be permeable and unsaturated. Permeability refers to the ability of soil or rock to transmit water, which is essential for infiltration—the process through which water on the ground surface enters the soil. When the soil is unsaturated, there are air spaces within the soil that can fill with water, allowing for movement and absorption.
If the ground were frozen, it would prevent water from entering, as the ice creates a barrier. A steep slope can lead to increased runoff rather than infiltration, as water tends to flow over the surface rather than penetrating into the soil. Saturated and impermeable land means that the soil or rock is already filled with water and cannot absorb any additional water, further inhibiting infiltration. Therefore, the conditions of being permeable and unsaturated are critical for the successful infiltration of water into the ground.