The flexible water barriers for controlling torrential waters, which we built at Krvavec last year, proved to be extremely effective during this year’s storms. The 16 barriers have gradually filled with material, reducing the channel gradient and preventing a new debris flow from reaching and damaging the cable car area.
After the 2018 landslide, the wider area around the Krvavec cable car remained highly exposed to erosion processes in the local torrents. Due to large amounts of unstable material in the torrent channels and banks, there was a risk of renewed or even larger debris flows. Krvavec therefore became an ideal site for the installation and testing of an extensive system of flexible mesh barriers, which are still rarely used in Slovenia for controlling torrential waters.
One of the largest water barrier installations in Europe
Instead of conventional barriers, flexible mesh barriers supplied by Geobrugg were installed at Krvavec. In terms of scale, this represented the supplier’s largest project of this type in Europe, with a total of 16 barriers installed within a single project. The barriers, ranging from 3 to 6 metres in height, were installed in two torrent channels: 12 barriers in Brezovški graben and 4 barriers in Lukenjski graben.
A key feature of flexible water barriers is that they are adapted to the specific location and are not emptied after being filled. The deposited material reduces the longitudinal gradient of the channel and supports the slopes, where excessive inclination could otherwise trigger further erosion and material movement. In the long term, the slopes become stabilized and the torrent bed is protected against erosion.
The effectiveness and importance of the flexible water barriers was also commented on by Dr Jošt Sodnik, Civil Engineer from Tempos d.o.o., who designed the barriers at Krvavec. He stated that this year’s storm event in Slovenia was an exceptional event, significantly exceeding the 2018 event. Despite this, the solution with a series of barriers proved effective. The area around the lower cable car station remained unaffected, as did the downstream section of the torrent channel. The main issues in the valley were caused by smaller tributaries downstream of the station.
“Detailed inspections showed manageable erosion damage on the sides of certain barriers, for which an analysis is already being carried out together with the manufacturer Geobrugg, and an appropriate solution will be provided. Based on drone footage analysis after the storm, approximately 19,000 m³ of material was deposited in the area of Brezovški and Lukenjski graben, where the mesh barriers were installed. This means that the barriers successfully retained this amount of material while also preventing erosion of the slopes and the torrent bed, which could otherwise have resulted in approximately 50,000 m³ of additional material burdening the channel and downstream settlements. Based on this, I can conclude that the implemented measure was successful and can represent good practice for addressing erosion issues and, above all, controlling sediment release, which proved critical in many areas during the recent storm event, alongside the extremely high water flows,” added Sodnik.
