Factors Influencing Point Measurement of Near-surface Saturated Soil Hydraulic Conductivity in a Small Sicilian Basin

Abstract

Hydraulic conductivity of saturated soil, Ks, controls many hydrological processes. Parameterization of basin hydrological models in terms of Ks is complicated and uncertain owing to the very high spatial variability of this soil property. A small Sicilian basin was intensively sampled by the simplified falling head technique to obtain spatially distributed Ks data, and an attempt to explain their spatial variability on the basis of soil physical characteristics, digital elevation model-derived topographic attributes and land cover was carried out. High Ks values were obtained when clay content was low and both elevation and mean slope were high. Moreover, differences in Ks among land cover classes were detected. However, soil texture was found to have a main role on Ks variability. This finding was supported by a subsequent intensive sampling of two areas differing by elevation and land cover. The conclusion was that, for the sampled basin, a good knowledge of the spatial distribution of the soil textural fractions is necessary to develop an appropriate sampling plan for Ks, regardless of both the position within the basin and land use.