Investigation on rainwater infiltration into layered shallow covers in pyroclastic soils and its effect on slope stability

The results highlight that the presence of coarse-textured unsaturated pumiceous layers, interbedded between finer ashy layers, can delay the wetting front advancement, thus initially confining the infiltration process within the uppermost finer layer. A diversion of the flow from the vertical towards the slope direction occurs when the soil approaches saturation. However, whereas a high hydraulic gradient establishes across pumices, water infiltration into the deepest layer begins, and part of the water crosses the pumices, before the complete saturation of the uppermost soil profile.