Soil Hydraulics Properties Estimation by Using Pedotransfer Functions in a Northeastern Semiarid Zone Catchment, Brazil

Hydrological modeling of the unsaturated soil zone fluxes allows the transfer processes simulation through the hydrological active soil zone. The pedotransfer functions (FTP) are useful tools in the modeling process. They contain analytical functions derived through statistic optimization process using a large amount of soil information data. This paper aims to analyze the level of reliability of two different pedotransfer functions [Wösten et al. (2001); Hodnett and Tomasella (2000)] by using field measurement of soil properties and experimental infiltration data through a disc infiltrometer in an experimental catchment at northeastern semi arid zone of Brazil. FTP’s used in this study were derived on previous studies by taking into account soils of different origins. The former FTP considers a large range of soil classes from temperate climate regions; the latter was derived through a selection of soils from tropical climate regions. The use of these pedotransfer functions showed a large variation between calculated soil hydraulic parameters. The tropical climate function seemed a better adjustment to the experimental data. Van Genuchten parameters and experimental infiltration data allowed the derivation of the unsaturated hydraulic conductivity and soil porewater tension functions. The derived soil hydraulic parameters showed spatial and temporal variation within the catchment.