Infiltration modeling

Many mathematical models for rainfall vertical infiltration into a soil matrix with horizontal surface are described. Firstly, classical approaches developed for regular rainfalls which keep continuous saturation at the soil surface and a more general formulation suitable for any type of rainfall pattern are considered for applications at the local (point) scale in homogeneous soils. Then, a simple model for point infiltration into a two-layered soil with a more permeable upper layer and a more complex model for any two-layered soil type are presented. Two field-scale infiltration models are also analyzed. One is of semi-empirical type and represents the spatial variability of saturated hydraulic conductivity, Ks, the other relies upon a semi-analytical/conceptual framework and combines the spatial heterogeneity of Ks with that of rainfall rate. Open problems linked with rainfall infiltration into surfaces with significant slopes are also discussed.