Search Results (10)

The Chiusella Valley (NW Italian Alps) is a key area for both the history of the alpine orogeny and its environmental context. It presents major structural features (including the Traversella neoalpine intrusion and a section of the Insubric line) and evidence of past climate changes in the region. Even if the Chiusella Valley was previously renowned for mining activities and most recently considered an alpine rural area with minor tourist attractions, its important geoheritage could offer alternatives to traditional mountain activities, which are facing adversity from increasing temperatures. This paper emphasises the role of geotourism in both enhancing sustainable development and raising awareness of climate change. For this purpose, the geodiversity of the Chiusella Valley has been analysed and several geosites have been identified. The research methodology includes field surveys, analysis of an existing educational activities and scientific literature, and assessment of geosites by quantitative analysis of five groups of indicators, including scientific, cultural, and educational values. The geosite selection within the Chiusella Valley reveals memories of past and present climate changes but also supports the development of targeted geotourism activities in the area. Additionally, a specific location has been identified for hosting indoor activities showcasing climate change action. These valuable contributions to sustainable geotourism provide opportunities for exploring the Alps in the vicinity of the Po Plain urban areas, while minimizing the environmental impact and facilitating educational activities on geodiversity and geoheritage. Full article

Debris flow is one of the most dangerous natural processes in mountain regions and it occur in a wide variety of environments throughout the world. In the Italian Alps, some tens of thousands of damaging debris flow and, in general, torrential floods associated to intense sediment transport in secondary catchments have been documented in the last 300 years. These have caused socio-economic damage, damage to anthropogenic structures or infrastructures and in many cases casualties. Often, in the same basins, the occurrence of debris-flow processes recurs many years later. Prediction can often be spatial and based on the magnitude of the largest known process, while the temporal forecast is the most uncertain. It is also possible to increase the resilience of the population and of the territory. The present study aims at investigating different levels of debris-flow hazard in urban areas on Alpine alluvial fans and proposes a strategy for debris-flow prevention based on historical research and on a simplified analytical approach, methods that also involve relatively low costs. For such analysis, Ischiator stream catchment (ca. 20 km²) and its alluvial fan (NW Italy) were selected. This area was partly affected by historical torrential flood associated to intense sediment transport and debris-flow processes. Present-day instability conditions along the slope and the stream network were detected and synthesized through surveys and aerial photo interpretation integrated by satellite images (period 1954–2021). An estimation of the potential amount of moving detritus, referred to as debris flow, was carried out regarding the June 1957 debris-flow event, based on the predictive models. The individual hazard index value was estimated based on different methods. The results indicate that 56% of the area is exposed to flood associated to intense sediment transport hazard, which fluctuates from high to very high levels; such results are supported by debris-flow historical records. Since today almost half of the settlement (Bagni di Vinadio) is located on potentially risk-exposed areas, the urban evolution policy adopted after the 1957 event failed to manage the risk connection to debris-flow activity. Full article

Snow gliding, a slow movement downhill of snow cover, is complex to forecast and model and yet is extremely important, because it drives snowpack dynamics in the pre-avalanching phase. Despite recent interest in this process and the development of some studies therein, this phenomenon is poorly understood and represents a major point of uncertainty for avalanche forecasting. This study presents a data-driven, physically based, time-dependent 1D model, Poli-Glide, able to predict the slow movement of snowpacks along a flow line at the daily scale. The objective of the work was to create a useful snow gliding model, requiring few, relatively easily available input data, by (i) modeling snowpack evolution from measured precipitation and air temperature, (ii) evaluating the rate and extent of movement of the snowpack in the gliding phase, and (iii) assessing fracture (i.e., avalanching) timing. Such a model could be then used to provide hazard assessment in areas subject to gliding, thereby, and subsequent avalanching. To do so, some simplifying assumptions were introduced, namely that (i) negligible traction stress occurs within soil, (ii) water percolation into snow occurs at a fixed rate, and (iii) the micro topography of soil is schematized according to a sinusoidal function in the absence of soil erosion. The proposed model was then applied to the “Torrent des Marais-Mont de La Saxe” site in Aosta Valley, monitored during the winters of 2010 and 2011, featuring different weather conditions. The results showed an acceptable capacity of the model to reproduce snowpack deformation patterns and the final snowpack’s displacement. Correlation analysis based upon observed glide rates further confirmed dependence against the chosen variables, thus witnessing the goodness of the model. The results could be a valuable starting point for future research aimed at including more complex parameterizations of the different processes that affect gliding. Full article

Rarely, a close correlation between wildfires and the occurrence of channelized debris flows has been observed in the Western Italian Alps. Only two cases in history have been reported, after brief and localized rainfall events of moderate intensity in Italy’s Piemonte region (NW Italy) caused debris flows, on 18 July 2005, in Verbania province (Pallanzeno municipality), and on June 2018 in Turin province (Bussoleno municipality). These phenomena occurred after a large portion of the catchments were affected by wide wildfires in the preceding months. Debris flow deposits showed an unusually large number of fine-grained particles, forming dark-brown mud-rich deposits associated with burnt wood deposits. Rainfall analysis related to the period between the wildfires’ occurrence and the debris flow events, using both raingauge and weather radar data, pointed out that the debris flows triggered in July 2005 and June 2018 were characterized by greater magnitude but associated with less precipitation intensity rates as compared with previous mud flows occurring just after wildfires. These behaviors can be explained by the presence of burned organic material and fine-grained sediment, generated from the soil’s thermal reworking, which formed a thick layer, centimeters deep, covering a large percentage of catchments and slopes. Most of this layer, generated by wildfires’ action were winnowed by rainfall events that had occurred in the months before the debris flow events, of significant magnitude, exhuming a discontinuous hydrophobic soil surface that changed the slopes’ permeability characteristics. In such conditions, runoff increased, corrivation time shortened, and, consequently, discharge along the two catchments’ channels-network increased as well. Consequently, the rainfall effects associated with rainfall events in July 2005 and June 2019 were more effective in mobilizing coarse sediments in channel beds than was typical for those catchments. Full article

The use of a Remotely Piloted Aircraft System (RPAS) for the characterization and monitoring of landslides has been widely improved in the last decade. In particular, the use of this system is particularly effective for the study of areas prone to geohazards. Zones affected by landslides, such as rock slides and debris flows, are often quite critical in terms of accessibility due to unstable blocs that can strongly limit the direct access to the studied area. In this paper, we present the case study of Ponte Formazza in NW Italian Alps. In June 2019, a massive and complex debris flow re-mobilized about 300,000 m³ of a rockslide deposit that occurred in 2009. In this particular environment, we tested traditional, direct and mixed photogrammetric approaches using various configurations of Ground Control Points (GCPs) of the photogrammetric block and by calculating the relative errors. The minimum configuration of GCPs was established to reduce in situ measurements without degrading the accuracy of the cartographic products. The images of three RPAS campaigns (2017, 2018 and 2019), processed with a Structure from Motion (SfM) technique, allowed us to obtain very high-resolution orthophoto and digital surface models (DSMs) before and after the 2019 event. A few GCPs, geolocated with a Global Navigation Satellite System (GNSS), improved the orthophoto and DSM quality (Root Mean Squared Error RMSE 5 cm) even in the areas far from the drone deployment. The availability of high-resolution models has been fundamental for the identification of the volume changes. Furthermore, the 3D view supported and completed the geomorphological mapping of affected areas, particularly in the areas where the field survey is dangerous. The use of ancillary meteorological data and Sentinel-2 satellite images allows for a better definition of the kinematics and the predisposal and triggering factors of the 2019 debris flow. Full article

We studied the effects of three soil management approaches (permanent grassing, chemical weeding, and buffer strips), and the additional impact of tractor passage on soil erosion in a sloping vineyard located in the inner part of Aosta Valley (N-W Italian Alps). The vineyard rows were equipped with a sediment collection system with channels and barrel tanks. A total of 12 events with sediment production were observed across 6 years, and the collected sediments were weighted and analyzed. Average erosion rates ranged from negligible (mainly in grassed rows) to 1.1 t ha⁻¹ per event (after weeding). The most erosive event occurred in July 2015, with a total rainfall of 32.2 mm, of which 20.1 were recorded in 1 h. Despite the limited number of erosive events observed, and the low measured erosion rates, permanent grassing reduced soil erosion considerably with respect to weeding; buffering had a comparable effect to grassing. The tractor passage, independent of the soil management approaches adopted, visibly accelerated the erosion process. The collected sediments were highly enriched in organic C, total N, and fine size fractions, indicating a potential loss of fertility over time. Despite the measured erosion rates being low over the experiment’s duration, more severe events are well documented in the recent past, and the number of intense storms is likely to increase due to climate change. Thus, the potential effects of erosion in the medium and long term need to be limited to a minimum rate of soil loss. Our experiment helped to compare soil losses by erosion under different soil management practices, including permanent grassing, i.e., a nature-based erosion mitigation measure. The results of the research can provide useful indications for planners and practitioners in similar regions, for sustainable, cross-sectoral soil management, and the enhancement of soil ecosystem services. Full article

In the 20th anniversary year of the European Geopark Network, and 5 years on from the receipt of the UNESCO label for the geoparks, this research focuses on geotourism contents and solutions within one of the most recently designated geoparks, admitted for membership in 2013: the Sesia Val Grande UNESCO Global Geopark (Western Italian Alps). The main aim of this paper is to corroborate the use of fieldtrips and virtual tours as resources for geotourism. The analysis is developed according to: i) geodiversity and geoheritage of the geopark territory; ii) different approaches for planning fieldtrip and virtual tours. The lists of 18 geotrails, 68 geosites and 13 off-site geoheritage elements (e.g., museums, geolabs) are provided. Then, seven trails were selected as a mirror of the geodiversity and as container of on-site and off-site geoheritage within the geopark. They were described to highlight the different approaches that were implemented for their valorization. Most of the geotrails are equipped with panels, and supported by the presence of thematic laboratories or sections in museums. A multidisciplinary approach (e.g., history, ecology) is applied to some geotrails, and a few of them are translated into virtual tours. The variety of geosciences contents of the geopark territory is hence viewed as richness, in term of high geodiversity, but also in term of diversification for its valorization. Full article

In full-scale snow avalanche test sites, structures such as pylons, plates, or dams have been used to measure impact forces and pressures from avalanches. Impact pressures are of extreme importance when dealing with issues such as hazard mapping and the design of buildings exposed to avalanches. In this paper, we present the force measurements recorded for five selected avalanches that occurred at the Seehore test site in Aosta Valley (NW Italian Alps). The five avalanches were small to medium-sized and cover a wide range in terms of snow characteristics and flow dynamics. Our aim was to analyze the force and pressure measurements with respect to the avalanche characteristics. We measured pressures in the range of 2 to 30 kPa. Though without exhaustive measurements of the avalanche flows, we found indications of different flow regimes. For example, we could appreciate some differences in the vertical profile of the pressures recorded for wet dense avalanches and powder ones. Being aware of the fact that more complete measurements are necessary to fully describe the avalanche flows, we think that the data of the five avalanches triggered at the Seehore test site might add some useful information to the ongoing scientific discussion on avalanche flow regimes and impact pressure. Full article

Mountain regions are vulnerable to climate change but information about the climate sensitivity of seasonally snow-covered, subalpine ecosystems is still lacking. We investigated the impact of climatic conditions and pedogenesis on the C and N cycling along an elevation gradient under a Larch forest in the northwest (NW) Italian Alps. The environmental gradient that occurs over short distances makes elevation a good proxy for understanding the response of forest soils and nutrient cycling to different climatic conditions. Subalpine forests are located in a sensitive elevation range—the prospected changes in winter precipitation (i.e., shift of snowfalls to higher altitude, reduction of snow cover duration, etc.) could determine strong effects on soil nitrogen and carbon cycling. The work was performed in the western Italian Alps (Long-Term Ecological Research- LTER site Mont Mars, Fontainemore, Aosta Valley Region). Three sites, characterized by similar bedrock lithology and predominance of Larix decidua Mill., were selected along an elevation gradient (1550–1900 m above sea level-a.s.l.). To investigate the effects on soil properties and soil solution C and N forms of changing abiotic factors (e.g., snow cover duration, number of soil freeze/thaw cycles, intensity and duration of soil freezing, etc.) along the elevation gradient, soil profiles were opened in each site and topsoils and soil solutions were periodically collected from 2015 to 2016. The results indicated that the coldest and highest soil (well-developed Podzol) showed the highest content of extractable C and N forms (N-NH₄⁺, DON, DOC, C_micr) compared to lower-elevation Cambisols. The soil solution C and N forms (except N-NO₃⁻) did not show significant differences among the sites. Independently from elevation, the duration of soil freezing, soil volumetric water content, and snow cover duration (in order of importance) were the main abiotic factors driving soil C and N forms, revealing how little changes in these parameters could considerably influence C and N cycling under this subalpine forest stand. Full article

Alpine glaciers are key components of local and regional hydrogeological cycles and real-time indicators of climate change. Volume variations are primary targets of investigation for the understanding of ongoing modifications and the forecast of possible future scenarios. These fluctuations can be traced from time-lapse monitoring of the glacier topography. A detailed reconstruction of the ice bottom morphology is however needed to provide total volume and reliable mass balance estimations. Non-destructive geophysical techniques can support these investigations. With the aim of characterizing ice bottom depth, ground-penetrating radar (GPR) profiles and single-station passive seismic measurements were acquired on the terminal lobes of Belvedere Glacier (NW Italian Alps). The glacier is covered by blocks and debris and its rough topography is rapidly evolving in last years, with opening and relocation of crevasses and diffuse instabilities in the frontal sectors. Despite the challenging working environment, ground-based GPR surveys were performed in the period 2016–2018, using 70-MHz and 40-MHz antennas. The 3D ice bottom morphology was reconstructed for both frontal lobes and a detailed ice thickness map was obtained. GPR results also suggested some information on ice bottom properties. The glacier was found to probably lay on a thick sequence (more than 40 m) of subglacial deposits, rather than on stiff bedrock. Week deeper reflectors were identified only in the frontal portion of the northern lobe. These interfaces may indicate the bedrock presence at a depth of around 80 m from the topographic surface, rapidly deepening upstream. Single-station passive seismic measurements, processed with the horizontal-to-vertical spectral ratio (HVSR) method, pointed out the absence of sharp vertical contrast in acoustic impedance between ice and bottom materials, globally confirming the hypotheses made on GPR results. The obtained results have been compared with previous independent geophysical investigations, performed in 1961 and 1985, with the same aim of ice thickness estimation. The comparison allowed us to validate the results obtained in the different surveys, supply a reference base map for the glacier bottom morphology and potentially study ice thickness variations over time. Full article