Pilots

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  Garmisch-Partenkirchen

  The Garmisch-Partenkirchen region is exposed to mountain hazards such as rock slope failure, rockfalls, debris flows and hyperconcentrated flows, massive sediment transport from rivers, avalanches and coupled multirisks. Recurrent extreme precipitation events in the last 3 decades caused well-documented multirisk events and show a clear dependency on intense summer rainstorms including the Hammersbach, Ferchenbach & Partnach Catchments, especially the Reintal- and Höllental and the touristic Partnachklamm & Höllentalklamm affected by multiple events e.g. in 1991, 2005, 2007, 2018/19, 2020 and 2022. Damages and hazardous process have been recorded over at least three decades providing a unique data set on rock slope failure, rockfalls, debris flows and hyperconcentrated flows and massive sediment transport events. Multi-risks have been well-documented and play a major role in the catchments and the touristic vicinity of the 30,000 inhabitant city of Garmisch-Partenkirchen. The clear link to intense summer precipitation makes the region especially susceptible to changing rainfall intensities in the foreseeable future in a changing climate. Risk-related management practices are already in operation but need to be updated for extreme and coupled events.

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  Gorenjska region, Slovenia

  Gorenjska region, more precisely the the Sora Basin, is a part of pre-Alpine/Alpine region in NW Slovenia. The most common weather events that affect the study area are droughts (agricultural, ecological and hydrological droughts) in combination with heatwaves, including flash droughts, river floods and flash floods. Co-occurrence of persistent dry conditions and high temperatures (heatwaves) leads to drought and several cascading impacts in different sectors - agriculture, forestry, local water supply, tourism, hydropower and ecosystems. Flash floods in combination with extreme precipitation cause the destruction of vegetation cover, damage on infrastructure etc. There is increasing trend of these weather events in the region, especially after 2000. In some years, the region was faced with a combination of different extreme weather events and their cascading/compound impacts. For example, in the year 2012, the region was faced with a combination of long-lasting hydrological drought, heatwaves and agricultural drought in the summer, and floods in the fall, which led to the synergy of various impacts. 

  In 2007 one of the worst natural disaster related to extreme weather event occurred in the area. In September 2007 an extreme rainfall event affected approximately one-third of the country. In the town Železniki, the observed maximum daily amount of rainfall was nearly 200 mm, which was the highest recorded amount of rainfall since the beginning of the measurements in 1930. The accumulated rainfall resulted in a flood event that by far exceeded the 100-year return period of maximal floods. The flash flood triggered by the intense precipitation devastated the town of Železniki: three people lost their lives, while it was estimated that the flood caused nearly 100 million Euros of damage. 

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  Val di Fiemme (Autonomous Province of Trento), Carezza and Latemar Area (Autonomous Province of Bolzano)

  In 2018, an event of intense rainfall and strong winds, called “Vaia”, affected the entire Central Alps, leading to the collapse of large forest areas and flooding events on both the minor and main network, with debris flows and flooding. The immediate effects of the event were evacuations, disruptions of road and technological network, even for long periods, both liquid and sediment flooding on large surface areas including settlements and agricultural land, and damage to river and torrent hazard mitigation measures. 

  The vast areas affected by the crashes also involved steep slopes that became new potential avalanche areas. Shortly after the storm they were indicated in the “hazard map” (“Carta/Mappa della Pericolosità”) of the Province of Trento and Province of Bolzano as potential avalanche hazard areas. 

  An expert study is required before making any modification to these areas. Another effect of extensive crashes is the increase of erosion-prone areas connected to the hydrological network and the alteration of the hydrological cycle, with a likely faster and more intense response to precipitation. 

  These areas, full of decaying wood, have later become open to bark beetle proliferation, which has proliferated in the last three years, affecting large areas outside the crashes and extending the modification in hydrologic, hydraulic and avalanche hazard. The aim of the project is to produce guidelines on how to deal with risk in these areas now, a few years after the storm: how to manage the regrowing forest from the point of view of the provincial Services for avalanche, torrent control and forest management, as well as from the Civil Protection perspective. 

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  Wipptal (ITA) + Stubaital (AUT)

  In the late afternoon of 08.16.2021, heavy rainfall in the Fleres valley caused widespread and extensive erosion phenomena in the Rio di Toverino basin. In the upper part, the debris of the Wetterstein dolomites found on the northern slopes along the ridge between the Seebergspitz, the Telfer Weißen and the Toffrinig-Lotterscharte was mobilized by reactivating the existing incisions. Most of the mobilized dolomite debris, ca. 25,000 m³ - 35,000 m³, was deposited on the gently sloping meadows at an altitude of approx. 1,580 m a.s.l. Further downstream there are only traces of dolomitic material. It can therefore be hypothesized that the flood wave, once the material was deposited in the middle basin, began to erode again in the downstream section, characterized by darker substrates; from an altitude of 1,425 m a.s.l. up to the apex of the alluvial fan, at about 1,200 m a.s.l., there were both widespread phenomena of slope erosion and deep erosion of the riverbed, which also reached depths of 2 - 2.5 m. Of note are the large quantities of timber mobilized and deposited in the valley. According to estimates, between 35,000 and 45,000 m³ of debris were deposited on the fan of the Rio di Toverino, which, added to the deposits in the middle basin, lead to a total of between 60,000 and 80,000 m³. The Rio di Fleres, following the blockage caused by the debris of the Rio di Toverino, underwent a drainage on the left orographic side, flowing between the buildings of the Botenhof, Kienast and Perl farms, on the state road and finally in its original bed, at the intersection of the LS35 with the access road to the Teissl farm. Several buildings were damaged, in particular number 117, where the regurgitation of the Rio Fleres heavily flooded the ground floor and the basement. Various infrastructures were also affected, including the hydroelectric derivation of the Toverino plant, which in turn was flooded, with interruptions in the power supply; two bridges on the provincial road were damaged, effectively isolating the hamlets upstream. Various sections of the forest and alpine roads were also submerged by debris.

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  Val d'Arly, France

  The event at the end of December 2018 linked to storm Eleanor, which caused multiple episodes of rain on snow, caused flooding in small watersheds in the Northern Alps (Haute-Savoie, Savoie and Isère) and the triggering superficial landslides and torrential lavas where, historically, these phenomena were exceptionally rare. On soils saturated with water, floods, landslides and mudslides have destroyed chalets and road infrastructure, particularly in Val d'Arly. The suddenly rising of the rain-snow limit, following heavy falls, consequences of storm Carmen, was followed on January 2 and 5, by heavy rains and snowfalls. In addition, the road network was heavily impacted by the avalanches, strongly influenced by the return from the East that occurred after the passage of the two storms. The large-scale aerosol caused extensive damage to the forest and caused material damage far in bottom of valleys, with a mixed flow over a wetter snowpack at lower altitudes.