Numerical and Experimental Study for Determining Hydraulic Parameters in Unsaturated Soils

Resumo

Studies to determine the hydraulic properties of unsaturated soils, named soil water characteristic curve
and hydraulic conductivity function, are generally carried out using laboratory measurements. Even though such
experiments are capable of producing accurate results they are time consuming, labor intensive and may not
represent large scales. In this context, this work sought to obtain the hydraulic parameters through inverse
modeling from the Monitored Infiltration field tests. Such approach provides a simple way to merge observed
data and models. The measurements for inversion procedures were carried out on a road embankment located in
Ouro Branco, Minas Gerais. To solve the generated problem the Finite Element based Hydrus 2D software package

was used to obtain the van Genuchten empirical parameters. In this process, the standard first order Levenberg-
Marquardt optimization algorithm was used, which is a local search method that generates a set of candidate

parameters around the initial values given by the user, which has the advantage of a high convergence rate. Thus,
the empirical parameters α e n, and the saturated permeability (Ksat) were estimated, while the, residual volumetric
moisture (θr) and saturated volumetric moisture (θs), were considered as known. Our results indicates that this type
of test is an accessible and accurate choice to calibrate soil hydraulic parameters.