The lateral saturated hydraulic conductivity, Ks,l, is the soil property that mostly governs subsurface flow in
hillslopes. Determinations of Ks,l at the hillslope scale are expected to yield valuable information for interpreting and
modeling hydrological processes since soil heterogeneities are functionally averaged in this case. However, these data
are rare since the experiments are quite difficult and costly. In this investigation, that was carried out in Sardinia (Italy),
large-scale determinations of Ks,l were done in two adjacent hillslopes covered by a Mediterranean maquis and grass, respectively,
with the following objectives: i) to evaluate the effect of land use change on Ks,l, and ii) to compare estimates
of Ks,l obtained under natural and artificial rainfall conditions. Higher Ks,l values were obtained under the maquis than in
the grassed soil since the soil macropore network was better connected in the maquis soil. The lateral conductivity increased
sharply close to the soil surface. The sharp increase of Ks,l started at a larger depth for the maquis soil than the
grassed one. The Ks,l values estimated during artificial rainfall experiments agreed with those obtained during the natural
rainfall periods. For the grassed site, it was possible to detect a stabilization of Ks,l in the upper soil layer, suggesting that
flow transport capacity of the soil pore system did not increase indefinitely. This study highlighted the importance of the
experimental determination of Ks,l at the hillslope scale for subsurface modeling, and also as a benchmark for developing
appropriate sampling methodologies based on near-point estimation of Ks,l.