Infiltration into crusted soils

Quasi-analytic methods are used to analyze ponded infiltration into crusted soils. The flux-concentration method provides accurate bridging between exact small-time similarity and large-time traveling wave solutions. Various studies have used one or, more of the following simplifications: neglect of gravity, replacing the crust with an hydraulic resistance, and use of the Green-Ampt model. If is shown that these approximations are unnecessary and obscure or distort the dynamics of infiltration into crusted soils. The role of the crust may be summarized as a throttle on infiltration. It reduces all four of infiltration rate, cumulative infiltration, degree of wetting, and depth of penetration. The hydrologic effects are to increase runoff and potential for erosion. Significant for irrigated and dry land agriculture is the harmful reduction of the water in the root zone available to plants.