Infiltration is the process by which water on the ground surface enters the soil). It is a critical link between surface hydrologic processes and subsurface water. The infiltration capacity is defined as the maximum rate of infiltration). Infiltration is a component of the general mass balance hydrologic budget). There are several ways to estimate the volume and/or the rate of infiltration of water into the soil). The rigorous standard that fully couples groundwater to surface water through a non-homogeneous soil is the numerical solution of Richards equation). The standard rigorous approach for calculating infiltration into soils is Richards equation, which is a partial differential equation with very nonlinear coefficients). Once integrated, one can easily choose to solve for either volume of infiltration or instantaneous infiltration rate).
Infiltration is not limited to hydrology and soil sciences. It can also refer to the passing of a liquid or gas through a substance by means of a filter. In military terms, infiltration refers to a system of transporting troops or vehicles at extended and irregular intervals so as to avoid enemy observation or attack, especially from the air.
