Abstract

ZAVALA, Manuel; SAUCEDO, Heber; FUENTES, Carlos  and  BAUTISTA, Carlos. Dual permeability model to water flow in Macroporous soils. Agrociencia [online]. 2012, vol.46, n.3, pp.205-220. ISSN 2521-9766.

The high presence of macropores in the soil causes the development of preferential flows significantly altering the hydraulic conditions in the medium. The detailed study of water flow for these conditions is discussed in the theory of dual conductivity, which represents the soil through two interconnected pore systems of contrasting hydraulic properties, one representing soil macropores and the other its porous matrix. However, this approach does not consider the laws by Laplace and Poiseuille to adequately represent the influence of the pore size of each medium in the water retention capacity and hydraulic conductivity. This study presents a one-dimensional numerical model to simulate water flow through soils with a strong presence of macropores, which describes the transfer processes developed in both media with two coupled Richards equations.The model incorporates analytical representations for the soil-hydrodynamic characteristics that consider the effect of the characteristic pore size of each medium on the resistance to flow water and water retention capacity. The spatial discretization of differential equations was performed using the Galerkin finite element method and time integration with a finite difference method. The nonlinearity of the systems resulting from the discretizations is treated with an iterative method of successive approaches. The model is applied to the simulation of infiltration scenarios with typical conditions of sprinkler and surface irrigation to show its power of description.

Keywords : fractal conductivity; water retention curve; Laplace law; Poiseuille law; large pores; geometric mean pore.

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