Knowledge of the soil hydraulic properties, such as the water retention theta(h) and hydraulic conductivity K(theta) curves, is indispensable for water and pollutant transport modeling of agricultural systems. Several experimental techniques have been proposed to determine these characteristic curves of the soil in the field. However, the complexity, the high costs and the time of execution of measurements are limiting factors for obtaining these characteristic curves in large areas. In this work, a simple methodology is shown, known as "Beerkan", which secks to overcome these difficulties. It uses experimental data of infiltration, bulk density and the particle-size distribution for estimating the theta(h) and K(theta) curves. This method was applied to two soils with different textural classification (three of an Oxisoil and three of an Alluvial Soil). For the hydrodynamic characterization, the shape and the normalization parameters of the theta(h) and of K(theta) curves were determined. The shape parameters depend upon the soil texture and they were obtained from the cumulative particle-size distribution curve; the normalization parameters depend on soil structure and they were obtained from the infiltration experiments using the simple ring infiltrometer. The Beerkan method proved to be robust and adapted to modeling the three-dimensional infiltration in field, as well as allowing the hydrodynamic characterization of the two soils.
hydrodynamic parameters; unsaturated soil; infiltration
