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Infiltration is the
movement of water into soil from the surface. Infiltration rate
is the rate at which water will enter a soil under specified
conditions. Infiltration rate is usually expressed as
centimeters per hour. Water infiltration is largely governed by
the surface properties of the soil.
A soil high in organic matter,
having good structure, and of medium to coarse texture
will usually have a rapid infiltration rate. Many other factors,
such as roughness of the ground surface, vegetative cover, and
slope, will also affect infiltration. Water movement within soil
also affects infiltration. Water already in the soil profile
must move downward before more water can enter at the surface.
The ease with which water moves
within a soil is termed permeability or hydraulic
conductivity. Permeable soils conduct water readily through
their mass. Other soils may conduct water slowly or have
restricting layers or horizons which limit or prevent downward
movement of water. Soils or soil layers which do not conduct
water, at all, are termed impermeable. Permeability, like
infiltration, is largely determined by texture, structure, and
organic matter content. Other factors, such as the dominant ion
on the exchange complex, presence of chemical cementing agents,
and type of clay minerals present, also influence permeability.
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New Mexico Climate Center: Movement of Water in Soil |
