CaracterizaÃÃo hidrodinÃmica de solos em campo e em laboratÃrio: anÃlise numÃrica e fractal / Hydrodynamic characterization of soils in the field and in laboratory: numerical and fractal analysis

AUTOR(ES)

Willames de Albuquerque Soares

DATA DE PUBLICAÇÃO

2004

RESUMO

The soil-water retention curve h(θ) and the hydraulic conductivity curve K(θ) were experimentally determined, from internal drainage and infiltration experiments, and estimated using the inverse method and pedo-transfer functions for a topsoil layer of two soils: a sandy soil contained in a lysimeter, and a Fluvent soil with loamy-sand texture, located in the experimental station of the Soil Physics group of the Department of Nuclear Energy - UFPE. For both soils, the volumetric water content and matric potential were obtained in an automated way and stored in a datalogger. In the inverse method, hydraulic functions were combined, thus forming the so-called classical models VGBC(B) (van Genuchten-Burdine /Brooks &Corey), VGBC(M) (van Genuchten-Mualem /Brooks &Corey), VG(B) (van Genuchten-Burdine) and VB(M) (van Genuchten-Mualem) and the fractal models: geometric mean pore (MG) model, neutral pore (PN) model, and large pore (PG) model proposed by Fuentes. The pedo-transfer functions used for h(θ) and K(θ) were those proposed by Rawls &Brakensiek and by Cosby, respectively. The implementation of the inverse method was accomplished by combining the hydrodynamic model, which solves the equation of Richards, with the sub-routine DBCONF that minimizes an objective function making use of the quasi-Newton method. The hydraulic function parameters were obtained by minimizing the sum of the squares of the deviations between the measured and the calculated volumetric water content. The soil-water retention curves predicted by pedo-transfer functions were considerably under estimated for both soils. The pedo-transfer functions provided satisfactory values for K(θ) only for the sandy soil. For the studied soils, the inverse method showed to be effective in the determination of the parameters for h(θ) and K(θ), with no significant differences in the ability to describe the experimental data from the classical models and fractal models. For both soils, the best classical model was VG(B) and the best fractal model was MG

ASSUNTO(S)

drenagem interna caracterizaÃÃo hidrodinÃmica solos engenharia nuclear anÃlise numÃrica e fractal fÃsica do solo

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