Hydrogeologic characterististics of roto-traslational slides in flysch

The hydrological characteristics of roto-translational slides in flysch are complex, due to the inherent anisotropy and heterogeneity of rock masses and related deposits. The paper deals with the hydrogeological characterization of a reactivated roto-translational slide affecting Cretaceous flysch rocks, located in the northern Apennines of Italy. Continuous monitoring of groundwater levels, in-situ permeability and pumping tests, hydrochemical analyses and uranine tracers were the adopted prospecting methods. Results showed that two overlaying aquifers exist at the slope scale: the first is unconfined, but highly compartmentalized, and hosted in the fractured and dismembered rock slide body. The second is confined and lays in the undisturbed flysch below the sliding surface. The latter is therefore a relevant factor for the instability of the slope. In this work, hydrologic monitoring and investigation are summarized, in order to support the analysis of landslide trigger mechanisms and to identify and design proper drainage system