Abstract Climate change has intensified across Alpine regions, causing significant alterations in precipitation regimes and snowpack levels, with notable implications for ecosystems and water availability both locally and downstream. This study investigates meteorological and hydrological droughts in the western Alps using the Standardized Precipitation Evapotranspiration Index (SPEI) and the Standardized Snowpack Index (SSPI). Drought duration, severity, and inter-index relationships were examined using the Seasonal Kendall (SK) test and the Bayesian Estimator of Abrupt change, Seasonality, and Trend (BEAST) to detect trends, seasonality, and abrupt shifts. The SK test revealed statistically significant decreasing trends across the region. More negative values of the SPEI index over longer timescales indicate worsening hydrological conditions, suggesting potential reductions in water availability and an increased risk of prolonged, severe droughts. Meanwhile, the BEAST analysis identified notable abrupt changes in both SPEI and SSPI, capturing increasing and decreasing shifts. These suggest that, while long-term trends indicate drying conditions, short-term increases likely associated with extreme weather events are also evident. These findings underscore the complexity of hydrological dynamics in the Alps and highlight the necessity for further detailed research to better understand and manage water resources resilience under changing climate conditions. Highlights − Climate change alters Alpine drought patterns, impacting water availability. − Western Alps analysis uses SPEI and SSPI indices to assess drought trends. − Trend analysis reveals drying trends, worsening hydrological conditions. − BEAST detects abrupt changes in drought linked to extreme weather events. − Findings highlight water resource risks, urging better resilience strategies. Graphical Abstract  This Graphical Abstract Provides an Overview of the Investigation into Meteorological and Hydrological Droughts in the Western Alps, a Region Increasingly Affected by Climate change-induced Shifts in Precipitation and Snow Levels. The Study Employs the SPEI and SSPI Indices To Assess Drought Duration, Severity, and the Correlation between Atmospheric and Hydrological Conditions (highlighted in Red in the Graphical Abstract). To identify trends, seasonal patterns, and abrupt changes, the analysis integrates two statistical methods: the SK test (represented in blue) and the BEAST algorithm (represented in green). The findings highlight the complexity of Hydrological dynamics in the Alps, with significant drying trends detected by the SK test and abrupt Shifts captured by BEAST. More negative SPEI values over longer timescales indicate worsening Hydrological Conditions, suggesting an increased risk of prolonged Droughts. These results emphasize the need for continuous monitoring and adaptive water resource management To mitigate risks in a changing Climate

Unraveling Drought Patterns and Abrupt Changes in the Western Alps: A Dual Index Approach

期刊论文
发表日期：

2025年4月30日

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Fabio Di Nunno,
Francesco Granata

摘要

Abstract

Climate change has intensified across Alpine regions, causing significant alterations in precipitation regimes and snowpack levels, with notable implications for ecosystems and water availability both locally and downstream. This study investigates meteorological and hydrological droughts in the western Alps using the Standardized Precipitation Evapotranspiration Index (SPEI) and the Standardized Snowpack Index (SSPI). Drought duration, severity, and inter-index relationships were examined using the Seasonal Kendall (SK) test and the Bayesian Estimator of Abrupt change, Seasonality, and Trend (BEAST) to detect trends, seasonality, and abrupt shifts. The SK test revealed statistically significant decreasing trends across the region. More negative values of the SPEI index over longer timescales indicate worsening hydrological conditions, suggesting potential reductions in water availability and an increased risk of prolonged, severe droughts. Meanwhile, the BEAST analysis identified notable abrupt changes in both SPEI and SSPI, capturing increasing and decreasing shifts. These suggest that, while long-term trends indicate drying conditions, short-term increases likely associated with extreme weather events are also evident. These findings underscore the complexity of hydrological dynamics in the Alps and highlight the necessity for further detailed research to better understand and manage water resources resilience under changing climate conditions.

Highlights

− Climate change alters Alpine drought patterns, impacting water availability.

− Western Alps analysis uses SPEI and SSPI indices to assess drought trends.

− Trend analysis reveals drying trends, worsening hydrological conditions.

− BEAST detects abrupt changes in drought linked to extreme weather events.

− Findings highlight water resource risks, urging better resilience strategies.

Graphical Abstract

This Graphical Abstract Provides an Overview of the Investigation into Meteorological and Hydrological Droughts in the Western Alps, a Region Increasingly Affected by Climate change-induced Shifts in Precipitation and Snow Levels. The Study Employs the SPEI and SSPI Indices To Assess Drought Duration, Severity, and the Correlation between Atmospheric and Hydrological Conditions (highlighted in Red in the Graphical Abstract). To identify trends, seasonal patterns, and abrupt changes, the analysis integrates two statistical methods: the SK test (represented in blue) and the BEAST algorithm (represented in green). The findings highlight the complexity of Hydrological dynamics in the Alps, with significant drying trends detected by the SK test and abrupt Shifts captured by BEAST. More negative SPEI values over longer timescales indicate worsening Hydrological Conditions, suggesting an increased risk of prolonged Droughts. These results emphasize the need for continuous monitoring and adaptive water resource management To mitigate risks in a changing Climate