Search

Shallow landslides are phenomena involving small parts of land and are triggered by huge intensity rainfall events of short duration or more moderate but prolonged over time. The area and thickness of such slips are typically reduced, but they are still harmful because there are no warning signs and no information on their possible evolution.Since the middle of the 20th century, heavy precipitation events have been more frequent and intense. In light of the current climate crisis, it is crucial to thoroughly examine the effects of these occurrences in order to establish triggering thresholds in mountain regions. This work deals with the experimental study of these landslides through the laboratory simulations on a small-scale slope, reproduced at the Gap2 lab of the Lecco Campus. Different experiments have been performed reproducing the seasonal conditions of the slopes. In particular, extreme rainfall events, soil conditions with different volumetric water content percentages were compared with moderate rainfall events in order to assess the different timing of landslide triggering.To investigate the behaviour of surface landslides under these conditions and to visualise in detail the processes related to water circulation, a multidisciplinary approach was adopted that consist of observations using geological, geophysical and photogrammetric methodologies and instrumentation. These technologies include modified pressure transmitters for the pore water pressure evaluation, GoPro’s cameras, TDR (Time Domain Reflectometry) for the volumetric water content evaluation and a georesistivimeter (IRIS Syscal Pro). In this way hydrogeological processes can be deeply analysed from different perspectives and can highlight peculiarities and assess in detail their evolution leading to collapse.Through the information obtained from geophysics, it is possible to visualise the formation of cracks within the landslide body in advance, also allowing considerations regarding the different water contributions of the simulated rainfall and the initial water content in the soil. The experimental results were then compared with a mathematical model.

Shallow landslides are induced by extreme hydrological events or by events of medium intensity but prolonged over time. Such slips involve generally limited portions of land; however, they are dangerous due to the absence of warning signals and the lack of knowledge regarding their possible evolution. The aim of this paper is to study the evolution of shallow landslides affected by snowmelt and rainfall and to compare the observations done in situ by means of a statistical analysis of meteorological variables with those made in the laboratory. Few authors have addressed the role of snow to slope instabilities, nevertheless, in the context of ongoing climate change, the study of glacier and snow melt must be further explored. For this reason, this work deals with the study of in situ seasonal processes observed at a mountain closed basin nearby Champoluc in Aosta Valley region. To understand and to improve triggering threshold in snowy region, snowmelt and meteorological analyses were carried out by means of a cutting-edge weather and snowpack station. All the available data have been examined with a series of statistical analysis to define snow melting trends in relation to meteorological conditions. After that, some tests were performed at GAP2 Lecco laboratory taking into account the onsite observations to evaluate the consequence of studied atmospheric conditions on a downscaled reproduced slope covered by snow. Therefore, it was possible to observe the direct interaction between soil and snow and how infiltration process takes place under settled conditions.

Mountain aquifers represent one of the largest and most valuable water sources, necessary to meet the population's water needs. Over time, they have been threatened by huge anthropogenic exploitation activities, which are currently leading to the depletion of aquifers in many regions worldwide. Furthermore, the vulnerability of groundwater resources is rapidly increasing due to climate change, urbanization, massive industry production, intensive agriculture, and breeding.Knowledge and forecasting about groundwater flow systems are required to guarantee proper management and territorial planning strategies, according to the mountain environmental evolution taking place. Besides, examining how groundwater storage mechanisms in different regions have changed in response to both climate-driven and anthropogenic effects is becoming increasingly crucial.In remote alpine areas, continuous monitoring and data collection of springs’ hydrogeological parameters is still often hampered by technical and logistical problems. In these contexts, new automated techniques and tools need to be applied to monitor springs’ hydrogeological parameters, punctually understanding the dynamics of exhausting of the available groundwater resources.The instrumentation and sensors complex, installed in correspondence with the Mascognaz spring basin (Aosta Valley, Italy) allows detailed analyses of the surface and underground groundwater system, recording continuously hydrogeological variables entering and leaving the spring recharge system. A cutting-edge weather station was here combined with a spring monitoring system through snowpack-hydrometeorological sensors installation. This setup, composed of a snow scale, ultrasonic and laser sensors for snow weight and snow depth reading, provides the possibility of a detailed study of the snow layer evolution during each season. Besides, a multiparametric probe allows water discharge, temperature and electric conductivity values detection.The high quality of the data provided and the small-size basin features have permitted highlighting the variables affecting the system and standing out those are evolving in time. Besides, the relationship between changes in weather conditions and water availability can be defined by performing correlations between different hydrogeological and meteorological available data series.The Mascognaz spring’s pilot site could be helpful as an example for other researchers and authorities who need to identify suitable instruments, sensors and methods to reconstruct the groundwater flow system and hydrogeological structure of a mountain basin.

The frequency and intensity of heavy precipitation events increased since the mid-20th century and, considering the climate crisis, it is important also to analyze the effects of processes and events that lead to faster snow mantle melting cycles in mountain areas.Shallow landslides are induced by extreme hydrological events such as the occurrence of short and intense rainfall or by events of medium intensity but prolonged over time. Such slips involve generally reduced portions of land both in area and in thickness, however, they are dangerous due to the absence of warning signals and the lack of knowledge regarding their possible evolution.This work deals with the experimental study of these landslides through the laboratory simulations on a small-scale slope, reproduced at the LIMAG Lab - Laboratory of mountain hydraulics and applied geology of the Lecco Campus and in situ seasonal processes observation at a mountain closed basin nearby Champoluc village in Aosta Valley region.The central objective is to study the evolution of shallow landslides in reduced scale caused by external factor as snowmelt and rainfall and to compare the observations done in laboratory with the ones in situ. In order to investigate the behaviour of shallow landslides in these critical conditions, a series of sensors have been installed on the simulator. This technology includes three modified pressure transmitters for the pore water pressure evaluation which have been accompanied by other support instrumentation consisting of GoPro’s cameras, TDR (Time Domain Reflectometry) and georesistivimeter; all of them provide a cross check of phenomena processes.Throughout the downscaled simulations with snow cover it was possible to observe several processes. The direct interaction between snow and ground does not favor the infiltration of a large amount of water. The protective role of snow lies in keeping the first film of soil at 0 degrees and loading the soil by decreasing its infiltrative capacity; this no longer occurs when the water melted by the snow flows downstream and begins to infiltrate into uncovered and warmer soils. Without thermal or overload barriers, the water pours into the ground. Therefore, a potential susceptible area can be the subject of different filtering and infiltrative contributions from upstream, saturating quickly and collapsing.These laboratory experiments are the starting point for the in-situ analyses and provide a comparison with the observations made by means of ad hoc instrumentation set up at the Champoluc station. Highly detailed information is obtained concerning the density and thickness of the snowpack during seasonal processes. These contribute to defining the hydrogeological processes within the terrain, already studied in the laboratory, and to establishing the water balance.