Marta Chiarle's research while affiliated with Italian National Research Council and other places

The water resource is severely compromised by climate change, and its availability and quality can no longer be taken for granted, even in places considered pristine, such as mountains. In this study, we evaluated the water colour variability of three artificial mountain lakes located in a relatively small basin (Western Italian Alps) at high elevations, and related this variability to the local climate conditions of the hydrological basin to which they belong. We estimated the dominant wavelength (DW) of lake water from Sentinel-2 acquisitions for the period 2017–2022, performing a chromaticity analysis. We correlated DW with climatic parameters recorded by two automated weather stations. Average DW varies from 497 nm of Serrù Lake and Agnel Lake to 512 nm of Lake Ceresole, where DW varies seasonally (variation of 75–100 nm in one year). During April–July, the DW of Lake Ceresole is significative correlated with air temperatures and snow cover (−0.8 and +0.8, respectively). During August–October, the relationship with temperature decreases to −0.5, and a correlation of 0.5 with the amount of rainfall appears. This work shows that mountain lake waters can exhibit variable quality (expressed here by water colour) in response to meteorological and hydrological conditions and events.

Climate change in the European Alps, in particular in the high-elevation environments, is causing an increase in mass movements and hazards. To learn more about relationships between mass movements and climate drivers, the location of the starting zone and date of the instability events need to be known. Nevertheless, not all existing inventories of mass movements are suitable for the purpose. For these reasons, we have implemented a specific inventory of mass movements which occurred in the Italian sector of the Alps at an elevation >1500 m. Currently, the inventory contains information relating to 772 mass movements. The most frequent types of processes documented are rockfall and debris/mud flows, with 279 and 191 cases respectively. The highest number of events occurred in 2022 (71 events), and an evident trend towards an increase over the years and during summer was found. This inventory is an excellent support tool for many activities that take place in and for the mountains, its consultation, both online and offline, makes the inventory suitable for use with different types of devices and can be used not only as a consultation tool on mass movements occurred in the past, but also to insert new events. This use can be particularly suitable for monitoring activities, managed by civil protection structures, municipalities, natural parks, environmental agencies, researchers, freelancers and so on.

Results of the annual glaciological survey (2022) conducted on Italian glaciers are here presented. About 250 volunteers operated last year in the three Alpine sectors (Piemonte - Valle d’Aosta, Lombardy and Triveneto) and in the Apennines (Calderone Glacier, Gran Sasso Group) observing two hundred and two glaciers. One hundred and eighteen glaciers were observed in the Piemonte - Valle d’Aosta sector while frontal variation was measured at the snout of sixty glaciers. Twenty-seven and fifty-seven glaciers were visited in the Lombardy Sector and in the Triveneto Sector, respectively (twenty-one and forty-three of which were measured, respectively). Mass balance measurements were conducted on nineteen Italian glaciers during the 2021-2022 hydrological year: four glaciers in the Western Alps (Piemonte - Valle d’Aosta sector), fourteen in the Eastern Alps (three in the Lombardy Sector, the other glaciers in the Triveneto Sector) and one in the Central Apennines.

The annual glaciological survey (2021) conducted on Italian glaciers is here presented. About 200 volunteers operated last year in the three Alpine sectors (Piemonte - Valle d’Aosta, Lombardy and Triveneto) and in the Apennines (Calderone Glacier, Gran Sasso Group). One hundred and one glaciers were observed in the Piemonte - Valle d’Aosta sector while frontal variation was measured at the snout of fourty-nine glaciers. Twenty-seven and fifty-two glaciers were visited in the Lombardy Sector and in the Triveneto Sector, respectively (seventeen and fourty-four of which were measured, respectively). Data for seventeen Italian glaciers monitored during the 2020-2021 hydrological year are reported in the section on mass balance measurements: four glaciers in the Western Alps (Piemonte - Valle d’Aosta sector), twelve in the Eastern Alps (two in the Lombardy Sector, the other ten glaciers in the Triveneto Sector) and one in the Central Apennines).

On August 5, 2022 in the Rochefort torrent (Val Ferret, Mont Blanc), a debris flow occurred that invaded the road connecting the valley with the village of Courmayeur. The debris flow interrupted the car traffic and damaged the bridge that crosses the torrent and the aqueduct that serves the municipality of Courmayeur. Due to the recurrence of similar events, in 2017 the Valle d’Aosta Region had decided to install a monitoring and warning system for debris flows, close to the bridge on the Rochefort torrent, to interrupt the traffic in both directions through a pair of traffic lights in case of debris flow. The system, named ALMOND-F (ALarm and MONitoring system for Debris-Flow), has been installed along the torrent, few tens of meters upstream of the bridge. ALMOND-F adopts a warning algorithm that is based on the variation of the seismic signal intensity produced by debris flows and that had been thoroughly tested in previous years in the instrumented area of the Gadria basin. On August 5, 2022 the warning system activated the traffic lights and stopped the traffic about three minutes before the debris flow invaded the road. It is the first time that the ALMOND-F system is utilized in a real risk situation to protect the population, after some years of controlled tests carried out in an instrumented area. Even though this represents an undoubted technological success, the installation of ALMOND-F requires several issues to be addressed to grant the highest level of safety. For instance, the presence of other active debris-flow channels and/or natural risks in the same valley may represent a limitation to the installation of a site-specific alarm system. The installation of the Rochefort torrent, opportunely optimized also on the basis of the feedbacks of the August 5, 2022 debris flow event, could become a useful case study and so provide indications and suggestions on the mitigation of the debris flow risk through the use of warning systems.

Alps are an important geographical area of the European continent and, in this area, temperature increase is most evident. However, the 1991–2020 climate normal in the Alps has still not been thoroughly investigated. Aiming to fill this gap with a focus on high-elevation environments, minimum and maximum daily air temperature acquired by 23 automatic weather station were used. The results show that the mean annual values of minimum and maximum temperature for the 1991–2020 climate normal in the Alps are −2.4°C and 4.4°C, respectively, with a warming rate of 0.5°C/10 years. The mean annual temperature comparison between 1961–1990 and 1971–2000, 1961–1990 and 1981–2010, 1961–1990 and 1991–2020 climate normal show an increase of 0.3°C, 0.5°C and 0.9°C, respectively. The results also confirm that seasonal and annual temperatures are rising through the whole Alpine arc, mainly in summer and autumn. This work highlights that annual minimum and maximum temperature do not seem to be affected by a positive elevation-dependent warming. Instead, a positive elevation-dependent warming in the maximum values of the annual minimum temperature was found. If anthropogenic emissions maintain the trend of the last decades, the expected mean annual temperature of the 2001–2030 climate normal is −0.2°C, with an increase of 0.5°C if compared to the 1991–2020 climate normal and with an increase of 1.5°C if compared to the 1961–1990 climate normal. This study highlights the warming rate that is now present in the European Alps, provides indications on the warming rate that will occur in the coming years and highlights the importance of carrying out investigations that consider not only the last 30-year climate normal, but also the most recent 30-year climate normal by comparing them with each other.