Abstract

ZAVALA, Manuel; SAUCEDO, Heber  and  FUENTES, Carlos. Fractal analytical models for the hydraulic properties of unsaturated soils. Agrociencia [online]. 2018, vol.52, n.8, pp.1059-1070. ISSN 2521-9766.

The predictive capability of the mechanicist models of the hydraulic properties of unsaturated soils must be known in detail before developing simulations of water transfer processes in the vadose zone of the soil. The aim of this study was to evaluate the flexibility of adjusting experimental data and the predictive capability of three fractal models for the soil-water retention curve and the hydraulic conductivity curve that satisfy the integral properties of infiltration (geometric pore, neutral pore and large pore). The models consider concepts of fractal geometry, the Laplace and Poiseuille equations and Darcy’s law; we established its level of description and performance in regard to two traditional mechanicist models. The evaluation included 208 soils selected from the Unsaturated Soil Hydraulic Database, which were used to cover nine texture types. The hydraulic conductivity experimental data were used to validate the conductivity fractal models. The linear correspondence analysis between theoretical and experimental data showed that the predictive capability of the fractal models for relative conductivity is good, since the coefficient of determination in the texture types was positive (>0.75 y <0.86). In this way, at least 75 % of the variability of the conductivity is explained by the adjusted regression model. The fractal models presented a higher prediction in regard to the combination of classic mechanicist models, used in soil physics.

Keywords : relative hydraulic conductivity; soil-water retention curve; fractal models; Laplace equation; Poiseuille equation and Darcy’s law.

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