Infiltration & Percolation in Relation to the Water (Hydrologic) Cycle
Infiltration is the seepage or entry of water into the soil. Infiltration constitutes the sole source of water to sustain the growth of vegetables, and it helps to sustain the growth of vegetation. It also helps to sustain the ground water supply to wells, streams, and springs.
The rate of infiltration is influenced by the physical characteristics of the soil (vis-à-vis, soil texture, structure, etc.), soil cover (i.e., plants), water content of the soil, as well as the slope of the ground, type of the soil, and the ground cover.
Precipitation may impact or fall directly to the ground surface or intercepted by plants, ultimately reaching the ground at a later time and in a more gentle and slower manner.
Once on the ground, water may infiltrate into the soil or move across the soil surface as runoff. Surface runoff occurs when the intensity of the rainfall is greater than the infiltration rate; or when the soil is at its water holding capacity (i.e., the soil is saturated).
Water holding capacity of soil and infiltration both depend on the soil texture and structure.
While clay soils have low infiltration rate due to the smaller sizes of their pore spaces, sandy soils allow water to infiltrate through them rapidly because of their larger, well connected pore spaces.
Infiltration is controlled by the soil structure, texture, vegetation, and the moisture state of the soil. While a high infiltration rate is tenable in dry soil, infiltration slows down as the soil becomes wet.
Coarse textured soils with large, well connected pore spaces often have higher infiltration rates than fine grained soils. In the same vein, coarse textured soil fills up more quickly than fine grained soils due to the smaller amount of their pore spaces per unit volume. Runoff on coarse textured soil is thereby more quickly attained than on fine grained soils.
Also read: Hydrological Cycle: What Is Water Cycle As It Relates To Engineering?
