Effects of Slope Movements on Soil Structure and Hydrological Response

Active slope movements can lead to continuous changes in soil macro-fabric, micro-structure and properties. In fact, depending on landslide mechanisms, the internal deformations which are induced by movement can deeply remould the mass, favouring formation of cracks and fissures; in addition, sliding leads to formation of an anisotropic shear zone just at the interface with the underlying stable formation. The result of movements and associated deformation phenomena is then a continuous change of soil properties thus of the hydrological and mechanical slope response. This is the focus of the paper, which discusses the key role of the shear zone on the groundwater regime, based on data collected during long-lasting investigations on some slow active earthflows in the Basento valley, Southern Italy. The results of simple calculations highlight some significant effects, which are generally neglected in conventional analyses of rainwater infiltration.