Impacts of Heavy and Persistent Precipitation on Railroad Infrastructure in July 2021: A Case Study from the Ahr Valley, Rhineland-Palatinate, Germany

Abstract

In contrast to river floods, the enormous erosion potential in catchments contributes significantly to the extent of damage to infrastructure in valleys. This paper investigates the impact of the heavy precipitation event of 14–15 July 2021 on the railroad in the Ahr valley in Rhineland-Palatinate, Germany. In a first step, a detailed overview of the climatological and hydrological drivers using spatially high-resolved precipitation distribution and peak discharge modeling is provided, and the event is placed in a broader context by comparing it to past flash flood events from 1910 and 2016. In a second step, a detailed mapping of damages along the railroad line is performed using aerial photographs. The mapping revealed that bridges are the weakest point during a flood event and that they contribute to an increase and modification of the flood wave through backwater effects. Since flood events are expected to increase in the future, there is an urgent need to increase the resilience of transportation to this hazard and to answer the question of what magnitudes and return periods of events should be used in future sizing of rail infrastructure.

Attribution of the heavy rainfall events leading to severe flooding in Western Europe during July 2021

“…Extreme rainfall occurred in Germany, Belgium, Luxembourg and neighbouring countries during the period 12 to 15 July 2021, leading to severe flooding, particularly in Western Germany and along the river Meuse and some of its tributaries in Belgium and the Netherlands. More than 200 fatalities (EM-DAT 2021) and considerable damage to infrastructure occurred, including houses, motorways and railway lines (Szymczak et al 2022). Road closures left places inaccessible for days, cutting them off from evacuation routes and emergency responders.…”

Radar‐based heavy precipitation events in Germany and associated circulation patterns

“…In the summer, such situations are frequently linked to the occurrence of low air pressure dominating the upper troposphere and corresponding depression near the ground, which causes an increasingly unstable stratification of the troposphere intensified by the inflow of warm and humid air masses, usually from the Mediterranean region. An example of such a situation is the low‐pressure system “Bernd,” which occurred over Central Europe in July 2021 and led to severe precipitation, flooding, serious infrastructure damages and fatalities (Szymczak et al, 2022). Also at that time, southwestern Germany, Belgium, Luxembourg and the Netherlands experienced a combination of persistent and recurrent heavy rainfall related to the slowly moving near‐surface depression intensified by the inflow of warm and humid air masses from the then exceptionally warm Baltic Sea.…”

Ready for Action! Destination Climate Change Communication: An Archetypal Branding Approach

“…For tourists, it can be disturbingly enlightening to realize that their favorite destination may vanish. Sinking island states in the Pacific [58], disappearing Alpine glaciers [59], wildfires in the Mediterranean [60], coral reef bleaching in Australia [61], and the dramatic floods of July 2021 in Germany and neighboring countries [26] are some of the widely known devastating effects of climate change on destinations.…”

“…While some destinations portray that they are immediately threatened by climate change (e.g., some Pacific islands), others experience climate change effects as accidental but more frequent occurrences [25] for example, in the case of floods of 2021 in Germany [26]. Some destinations even view climate change as an opportunity by promoting longer, hotter seasons or "last chance tourism" (e.g., polar bear viewing industry in the Arctic) [27].…”