Wolf's hanger
A Wolfsches Gehänge (also Wolfsches Schwebewerk , after the royal Bavarian building officer August Wolf) is a parallel work in hydraulic engineering from rows of piles with attached fascines . It was designed to be the tributaries strong bedload leading rivers quickly silt up to leave.
Working principle
In the 19th century, the then still meandering large rivers began to be made navigable by straightening them with the further aim of reducing the risk of flooding for localities in the river lowlands by building dams and silting up the tributaries. This was done either by piercing the bends in the river, as in the case of straightening the Rhine, or by creating new bank lines and thus narrowing the river bed . For this purpose, tail units were built in the river, which were connected to the existing bank by transverse structures. The area between the tail unit - in principle the palisades standing in the river - and the previous bank silted up over time.
In the large mountain rivers previously used for rafting , there was the problem that fixed tail units did not allow the relatively coarse-grained material (called debris) carried along the river bed to pass through and the clear waters hardly carried any fine suspended matter that would have silted up the backwaters . Furthermore, it was feared that the tail units would be damaged by the heavy debris flow during the floods of the snowmelt in spring. To counter this, the Bavarian building councilor August Wolf designed tail units and transverse structures that were not solid, but permeable towards the backwater. He chose the shape of a pole fence supported by posts, on the underside of which fascines were attached to float in the water. In this way, this suspension also allowed coarser stones to pass on the river bed - but only in the direction of the oxbow lake - and at the same time slowed the current near the bank, which accelerated the deposition and siltation. In the 1880s he achieved quick successes in regulating the Isar with little effort, so that Wolf's hanger was also used in other river regulations. In the course of time, the fascines turned out to be less of an essential element than the piles, which alone were responsible for changing the direction of the current and transporting the bed load through the spaces between the piles into the silted tributaries. After silting up, the suspension system was simply integrated into the new bank reinforcement and built over.
Today, a further regulation of wild rivers in Central Europe is no longer sought, rather the creation of new retention areas for flood protection is propagated. Nevertheless, Wolf's hanger is still used, namely for structural improvement in the renaturation of water bodies.
literature
- August Wolf and Specht: About river corrections on the Isar in the Landshut building authority district. In: Wochenblatt für Baukunde 1885, p. 344; 1886, p. 24.
- August Wolf: Regulating rivers and watercourses carrying debris. In: Wochenblatt für Baukunde 1886, p. 739.
- August Wolf: Newer electricity structures on the Isar. In: Zeitschrift für Bauwesen 36, 1886, Sp. 515-528. ( online , p. 265)
- Max Buchwald: Taming the watercourses in the mountains. In: Prometheus. Illustrated weekly on the progress in trade, industry and science , Volume 28, No. 1446, 1917, pp. 647–648. ( online , p. 6)
Individual evidence
- ↑ Hangers (2) , in Lueger , Lexicon of Entire Technology , 1904
- ↑ About newer river engineering methods and about the last flood in Cilli , lecture by the chief engineer Kajetan Krischan, held at the weekly meeting of the Graz Polytechnic Club on November 22nd. J., in: Deutsche Wacht of December 12, 1901, 26th year, issue 99.
- ↑ Eduard Faber: The improvement of the bed load-guiding rivers embedded in a moving floor, in: Memorandum on the improvement of the navigability of the Bavarian Danube and on the implementation of large-scale shipping to Ulm. Munich, 1905, p. 61 ( PDF online , 1.87 MB)
- ↑ Revitalization of small rivers in mountain and hill country: water structure improvement and compensation of water flow , report on the conference of the Society for Engineering Biology on September 3rd and 4th, 2004 in Lichtenfels ( Memento from June 26th 2013 in the web archive archive.today )