Caratterizzazione e monitoraggio idrogeologico della frana di Lamosano

In the study of landslide phenomena, it is important to characterize the area from the hydrogeological point of view, identifying and characterizing the main hydrogeological units with a geotechnical model, measuring of local hydraulic conductivity values and observing the trend of the hydraulic head inside units, to evaluate the presence, or absence, of a relationship between the former and precipitation. The application of this procedure was used for the characterization of the Lamosano landslide, (north-Eastern Italian Alps, near Belluno), a slow, slope movement which started in the sixties and affects the medium-surface layers of the area, related with the groundwater level and excursion. This type of analysis allowed the individuation of 4 different hydrogeological units: quaternary deposits, fractured marls (shallow weathered portion of the Bolago Marls unit), massive marls (deep portion of the Bolago Marls unit) and sandstones. The surface layers of quaternary deposits and fractured malrs are characterized by different local hydraulic conductivity (from 2.41E-05 m/s to 2.60E-08 m/s) and showed the same behaviour, with a high escursion of groundwater level after precipitation (about 2.0 m). The deepest units, consisting of compact marl and sandstone, are characterized by a very different behavior compared to those surface units, one which is not affected by precipitation events and presents a very limited annual excursion of the hydraulic head and low hydraulic conductivity values (about 2.22E-08 m/s). In view of a future drainage project for the reduction of hydraulic head excursions we can report, through this study, the Quaternary deposits and the fractured shallow portion of the Bolago marls, as possible units in which this work could have a significant response.