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 groundwaterflow in low-permeability media affected by deep Apennine landslide, involving sev-eral million cubic meters of soil and rock. Rainfall and groundwater circulation areamong 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, inthis study, combined hydrogeological, geochemical and isotopic investigation wereperformed in order to: (1) characterize infiltration and flow processes and (2) under-stand the role of sliding surface on groundwater circulation in a complex landslidethat mainly involves sandstones and clay materials. Results indicate that at least twocircuits coexist: a faster one, where rainfall preferentially infiltrates and flows in awell-connected network of macropores, cracks and soil pipes, which mainly feeds thesprings; a slower and a deeper one that flows in the soil matrix and fractures of thelandslide body. Moreover, the investigated slip zones show an aquiclude characteris-tic in terms of groundwater circulation, where the flow is very slow and precipitationinfluence is negligible. These results could be helpful in an accurate slope stabilityconsiderations and to improve the reliability of landslide risk assessment.