Processes and factors controlling the groundwater flow in a complex landslide: A case study in the northern Italy

The present work provides new insights on some factors controlling the groundwater flow in low-permeability media affected by deep Apennine landslide, involving several million cubic meters of soil and rock. Rainfall and groundwater circulation are among the major triggers of landslides. However, if the first factor is well studied, only few research deal with the hydrogeological processes in the landslide. Thus, in this study, combined hydrogeological, geochemical and isotopic investigation were performed in order to: (1) characterize infiltration and flow processes and (2) understand the role of sliding surface on groundwater circulation in a complex landslide that mainly involves sandstones and clay materials. Results indicate that at least two circuits coexist: a faster one, where rainfall preferentially infiltrates and flows in a well-connected network of macropores, cracks and soil pipes, which mainly feeds the springs; a slower and a deeper one that flows in the soil matrix and fractures of the landslide body. Moreover, the investigated slip zones show an aquiclude characteristic in terms of groundwater circulation, where the flow is very slow and precipitation influence is negligible. These results could be helpful in an accurate slope stability considerations and to improve the reliability of landslide risk assessment.