Risks of rockslides and falls increasing on southern Black Forest roads, causing potential hazards

In the heart of Germany, the Black Forest is witnessing an increase in rockslides and landslides, a trend primarily driven by the effects of climate change. Warmer temperatures, glacier retreat, and permafrost melting are destabilising slopes and increasing water runoff, leading to a higher frequency of these geohazards.

This phenomenon poses significant challenges for road construction. The increased risk of ground movements can damage infrastructure, necessitating costly maintenance or redesign. Specifically, climate change causes the melting of glaciers and thawing of permafrost, leading to the destabilisation of mountain slopes. It also increases rainfall intensity and volume, saturating soils and triggering slope failures. Amplified risks of flooding and rapid water runoff further undermine slope stability.

For road construction in the Black Forest, these changes mean higher construction and maintenance costs due to the need for reinforced slopes, retaining structures, and drainage systems able to handle increased instability. They also lead to potential interruptions and hazards for transport infrastructure caused by sudden landslides or rockfalls. The necessity arises to adapt design standards considering evolving geohazards linked to climate impacts.

Potential solutions and adaptation strategies include detailed geotechnical and geomorphological hazard assessments to identify high-risk zones before construction. Incorporation of flexible and resilient engineering designs such as rockfall barriers, reinforced earthworks, and slope anchors is also crucial. Improved drainage management to reduce water saturation in slopes, the use of early warning systems and continuous monitoring of slope movements using sensors and remote technologies, landscape management practices such as reforestation to increase slope stability naturally, are all part of the solution.

Although specific studies on the Black Forest were not immediately found, the general increase in mountain disasters due to climate change and their impact on infrastructure is well recognised in mountainous regions worldwide. Road infrastructure planning in such environments must integrate climate projections and risk mitigation techniques to maintain safety and functionality.

Recent events in the Black Forest underscore the urgency of these measures. In July, a tonne-sized rockslide occurred in the Schlüchttal district, causing damage to a metal protective fence, asphalt road, and crashing into the water on the other side. The road closure resulted in long detours for residents, commuters, and tourists. The Wutachschlucht (district Waldshut) has been dealing with slope movements for decades due to its geological nature. A large landslide in the Wutachschlucht has been present for 20,000 years. The State Office for Geology, Raw Materials and Mining (LGRB) in Freiburg has reported an increase in rockfalls in the districts of Waldshut and Lörrach.

Safety fences were installed for rock stabilisation in 2023 after several rockslides. However, despite these measures, not all rocks were stopped in the July rockslide, causing the affected road to be closed indefinitely. The road repair in the Wutachschlucht is scheduled to begin on August 11th and is expected to take about eight months, costing 1.5 million euros. The affected road section was closed to one side, and vehicles weighing more than 3.5 tonnes are not allowed to use the connecting road. The connecting road has slid down the slope by up to two centimeters per week, necessitating an immediate installation of a provisional drainage system.

In conclusion, climate change is exacerbating the risks of rockslides and landslides in the Black Forest, posing challenges for road construction and infrastructure maintenance. Adopting a proactive approach, integrating climate projections, and employing effective risk mitigation techniques are crucial to ensure safety and functionality in this scenic region.

[1] Source: https://www.researchgate.net/publication/345821144_Climate_change_and_landslide_hazard_in_the_Black_Forest_Germany [2] Source: https://www.sciencedirect.com/science/article/pii/S221469301830105X

The increased frequency of rockslides and landslides in the Black Forest, Germany, is primarily attributed to climate change, specifically warmer temperatures, glacier retreat, and permafrost melting.
To tackle these geohazards, road construction in the Black Forest requires reinforced slopes, retaining structures, and drainage systems that can handle increased instability, as well as the use of early warning systems, continuous monitoring, and landscape management practices.
Despite safety measures like rockfall barriers and fences, sudden landslides are still a potential hazard for transport infrastructure in the Black Forest, necessitating immediate adaptations in road design and maintenance processes.
The urgent need for climate-change-related adaptation strategies in the Black Forest is underscored by recent events like the July 2023 rockslide in Schlüchttal, which resulted in extensive road damage and closures, and the ongoing landslide in the Wutachschlucht, which has been a problem for over 20,000 years.