Spatial and temporal variability of saturated hydraulic conductivity in a central Sicily soil

The spatial and temporal variations of the field-saturated hydraulic conductivity (K-fs) at the surface of a sandy-clay soil were investigated by the pressure infiltrometer method in a noncultivated field of 1000 m(2) having a complex morphology. The K-fs was measured in an upslope zone, having a slope of 33%, and in a downslope zone, with a slope of 13%. In winter, the K-fs, values measured upslope (8.2 mm h(-1)) were substantially higher than those obtained downslope (0.4 mm h(-1)). In summer, K-fs increased up to 32.8 mm h(-1) in the upper zone and to 11.9 mm h(-1) in the lower one. The very noticeable seasonal variability of K-fs observed downslope was probably due to the cracking of the surface crust. The within measurement zone spatial variability of the K-fs values did not change appreciably with either the slope location or the season (coefficients of Variation of 55-76%). Identification of the areas potentially producing surface runoff in semi-arid environments may need detailed investigations both in space and time also in relatively small fields, especially when they are characterized by a complex morphology.