Infiltration

Infiltration losses consists of the rainfall that percolates into the soil matrix and down towards the water table.  In fact most infiltration is not lost overall, but becomes recharge to the groundwater for use in transpiration (uptake by plants) or replenishing of aquifers.  However, for short term simulations where the focus is on flooding they are considered losses.

Important physical properties that determine infiltration include land use and soil.  The land uses (i.e. agricultural, forest, urban, etc.) determine how well the water is held or detained so that infiltration into the soil matrix can occur.  For example, it is more difficult for water to move quickly through thick foliage than across the pavement and concrete of an urban environment and so we would expect more infiltration in forested areas than urban ones.  Further, the tilling of agricultural lands "loosens" the soil making infiltration higher than in areas where soils are more compacted or consolidated.