Modeling cumulative infiltration into cracking soils

An analytical solution of rain infiltration into dry cracked soil are presented and validated with experimental data. Particular emphasis is placed on the calculations of the post-incipient ponding phase and the cumulative infiltration amount. The morphology of the cracks is represented in a simple manner in terms of a length scale of crack spacing and geometric pattern. The crack volume is estimated in terms of an antecedent bulk density and a reference crack free density. The analysis utilizes the wetting front solutions of horizontal diffusion into the soil matrix governed by Richards' equation as developed by the present authors, recently. The soil matrix diffusion characteristic parameters, which are needed in this solution, are determined experimentally for the cracked soil under study. In the simple geometric representation of the prismatic column structure assumed here, an accurate estimation of the crack volume is made in terms of bulk density measurements from which ponding time estimates are made in closed form. Closed form expressions are also derived for the cumulative infiltration amount. The analytical results are compared with the data being obtained at the National Sedimentation Laboratory from an experimental set up using a Mississippi delta clay soil.