Hydraulic Conductivity on Soil Monoliths of Central Chile

Four monoliths with contrasting textural classes (S-c, S-cl, S-sl and S-ls) from soils (Fluventic Haploxerolls and Typic Xerochrepts) of central Chile were used to obtain soil hydraulic conductivity at different slope gradients (0%, 15%, 20% and 25%) with tension infiltrometer, under laboratory conditions. A total of 13 supply pressure heads (psi(s), between -140 and -20 mm) were used to obtain the unsaturated hydraulic conductivity (K-psi). Paired data [ln(K-psi) y psi(s)] were adjusted by two-linear models that assumed a continuous exponential function in a macroporous and mesoporous system, which considered a boundary supply pressure head. Extrapolating to zero supply pressure head, field saturated hydraulic conductivity (K-fs) was estimated. In all soils, when a gravitational adjustment to supply pressure heads was used, K-fs values were strongly negatively correlated to slope gradient. It is attributed to a refraction of water flow, which considered the greater frictional or viscous resistance generated by inclination.