Marrosu, Roberto (2019) Investigation on lateral saturated soil hydraulic conductivity evaluated at different spatial scales in a Mediterranean hillslope. Doctoral Thesis.
Lateral saturated hydraulic conductivity, Ks,l, is the soil property that mostly governs subsurface flow in shallow soils of steep hills. Hence, Ks,l characterizing is crucial for understanding and modelling the hydrological processes at the hillslope and catchment scales. Although several methods have been developed so far to measure Ks,l, reliable determinations of this property is challenging due to anisotropy and scaling effects of spatio-temporally variable soil heterogeneities on Ks,l measuring. The thesis investigates the changes of Ks,l estimations as a function of soil volume sampled with a given measurement technique based on drainage experiments carried out by a drain, large volume monoliths and on small soil cubes, representative for hillslope, plot and point spatial scales, respectively. The observed discrepancies between the considered scales were mainly attributed to macropore flow and the difficulty in adequately embodying the macropore network on smaller sampled soil volumes. However, at the plot-scale, the sampled volume was sufficient to effectively represent the large-scale hydrological effects of the macropore network. This suggests that performing drainage experiments at this scale is a promising method for routinely characterizing lateral conductivities over large spatial scales. Overall, the thesis provided useful information for the hydrological characterization of soils in semiarid Mediterranean regions, where water management and conservation are critical.
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