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A rapid sequence of cascading events involving thermokarst lake outburst, local rock glacier front failure, debris flow development, and river blockage hit Radurschl Valley (Ötztal Alps, Tyrol) on 13 August 2019. Compounding effects from permafrost degradation and drainage network development within the rock glacier initiated the complex process chain. The debris flow dammed the main river of the valley, impounding a water volume of 120 000 m 3 that was partly drained by excavation to prevent a potentially catastrophic outburst flood. We present a systematic analysis of destabilizing factors to deduce the failure mechanism. The identification and evaluation of individual factors reveals a critical combination of topographical and sedimentological disposition, climate, and weather patterns driving the evolution of a thermokarst drainage network. Progressively changing groundwater flow and storage patterns within the frozen sediment accumulation governed the slope stability of the rock glacier front. Our results demonstrate the hazard potential of active rock glaciers due to their large amount of mobilizable sediment, dynamically changing internal structure, thermokarst lake development, and substantial water flow along a rapidly evolving channel network. [ABSTRACT FROM AUTHOR]

Early Springs (ES), March and April in particular, have been extremely dry in Central Europe in recent years, particularly from 2003 onwards. This is causing substantial impacts, foremost to agriculture, which is heavily dependent on sufficient moisture supply at the beginning growing season. However, the drivers of ES droughts are still not well understood. In this article, we investigate the temporal evolution of ES precipitation anomalies for the period 1860–2020 over Central Europe and the driving large‐scale atmospheric circulation conditions. Two periods of ES drought conditions stand out, the most recent period (2005–2020) and another one during the middle of the 20th century (1926–1950) which show sustained negative precipitation anomalies in ES with only a few exceptions. The positive phase of the East Atlantic/Western Russia surface air pressure patterns is found as the main driver of ES precipitation deficit. Further analyses reveals an important role of positive western Atlantic sea surface temperature anomalies. These drive a Rossby wave response, resembling the positive phase East Atlantic/Western Russia pattern. Although the given evidence points towards internal multidecadal North Atlantic variability driving the warming patterns, anthropogenic warming from enhanced greenhouse gas emissions cannot be discarded as additional forcing of the recent ES drought period. [ABSTRACT FROM AUTHOR]

A rapid sequence of cascading events involving thermokarst lake outburst, rock glacier front failure, debris flow development and river blockage hit Radurschl Valley (Ötztal Alps, Tyrol) on 13 August 2019. Compounding effects from multivariate permafrost degradation and drainage network development initiated the complex process chain. The debris flow dammed the main river of the valley, impounding a water volume of 120,000 m³ that was partly drained by excavation to prevent a potentially catastrophic outburst flood. Since the environmental forces inducing the debris flow evolved under ambiguous conditions, potentially destabilizing factors were analyzed systematically to deduce the failure mechanism and establish a basis for multi hazard assessment in similar settings. Identification and evaluation of individual factors revealed a critical combination of topographical and sedimentological disposition, climate, and weather patterns driving the evolution of thermokarst and debris flow. Progressively changing groundwater flow and storage patterns characterizing the hydraulic configuration within the frozen sediment accumulation governed the slope stability of the rock glacier front. The large amount of mobilizable sediment, dynamically changing internal structure, and substantial water flow along a rapidly evolving channel network eroded into the permafrost body, render active rock glaciers complex multi hazard elements in periglacial, mountainous environments. [ABSTRACT FROM AUTHOR]

In this paper future changes of surface water availability in Austria are investigated. We use an ensemble of downscaled and bias-corrected regional climate model simulations of the EURO-CORDEX initiative under moderate mitigation (RCP4.5) and Paris agreement (RCP2.6) emission scenarios. The climatic water balance and its components (rainfall, snow melt, glacier melt and atmospheric evaporative demand) are used as indicators for surface water availability and we focus on different altitudinal classes (lowland, mountainous and high alpine) to depict a variety of processes in complex terrain. Apart from analysing the mean changes of these components we also pursue a hazard risk approach by estimating future changes in return periods of drought events of a given magnitude as observed in the reference period. The results show in general wetter conditions over the course of the 21st century over Austria on an annual basis compared to the reference period 1981-2010. Considering seasonal differences, winter and spring are getting wetter due to an increase in precipitation and a higher fraction of rainfall as a consequence of rising temperatures. In summer only little changes in the mean of the climatic water balance conditions are visible across the model ensemble. On the contrary, by analysing changes in return periods of drought events, an increasing risk of moderate and extreme drought events during summer is apparent, a signal emerging within the climate system along increasing warming. [ABSTRACT FROM AUTHOR]

Drought affects even mountain regions, despite a humid climate. Droughts' damaging character in the past and an increasing probability in future projections call for an understanding of drought impacts in the European Alpine region. The European Drought Impact Report Inventory (EDII) collects text reports on negative drought impacts. This study presents a considerably updated EDII focusing on the study region of the greater Alpine Space. This first version release of an Alpine Drought Impact Inventory (EDIIALPS) classifies impact reports into categories covering various affected sectors and enables comparisons of the drought impact characteristics. We analyzed the distribution of reported impacts on the spatial, temporal and seasonal scale, and by drought type for soil-moisture and hydrological drought. For the spatial analysis, we compared the impact data located in the Alpine Space' to entire Europe. Further, we compared impact data between different climatic and altitudinal domains (Northern vs. Southern region, pre-Alpine vs. high-altitude region), and between the Alpine countries. Compared to entire Europe, in the Alpine Space agriculture and livestock farming impacts are even more frequently reported, especially in the Southern region. Public water supply is second most relevant sector, but overall less prominent compared to Europe, especially in spring when snowmelt mitigates water shortages. Impacts occurred mostly in summer and early autumn with a delay between those impacts initiated by soil-moisture and those by hydrological drought. The high-altitude region showed this effect the strongest. From 1975 to 2020, the number of archived reports increased, with substantially more impacts noted during the drought events of 1976, 2003, 2015 and 2018. Moreover, reported impacts diversified from agricultural dominance to multi-facetted impact types covering forestry, water quality, industry and so forth. Though EDIIALPS is biased by reporting behaviour, the amount of more than 3200 compiled reports on negative drought impacts demonstrates the need to move from emergency actions to better preparedness. These may be guided by EDIIALPS' insights to regional patterns, seasons and drought types. [ABSTRACT FROM AUTHOR]