Analytical model for preferential infiltration into cracks in soils

Cracks induce preferential flows in many soils, creating the need for analytical solutions to describe the preferential infiltration processes. In response, the Green–Ampt infiltration model is first applied within the aggregate-crack dual-domain model to distinguish water movement through aggregate versus through crack. In addition, using a set of non-dimensional parameters to generalize the analytical model, the developed model can estimate the infiltration and depth of wetting due to the preferential flows during the constant-intensity rain. The results show that the infiltration partitioning varies with time, with flow regimes changing at the time of ponding of the aggregate and again at the time when the crack abounds with water. The fraction of preferential infiltration increases monotonically as a function of the rainfall intensity and the relative volume of the crack domain. Conversely, the wetting depth in the crack domain decreases monotonically as a function of the relative volume of the crack. Finally, the proposed analytical model is compared with HYDRUS-1D numerical simulations based on the Richards equation for three soils with cracks. The analytical model closely approximates the numerical results, so as to provide a novel insight into the preferential infiltration dynamics during rainfall events for the cracks in soils.