Renaturation of the Klingenbach stream in Breckenheim town center"
In Breckenheim, the Klingenbach was heavily obstructed and therefore in a poor ecological condition. To improve this, a 55-metre section of the stream was renaturalized by the environmental agency in 2020.
In the area of Breckenheim, the Klingenbach was characterized by a massive revetment of the bed and banks. This was presumably constructed in order to quickly divert flood runoff through the village and to minimize maintenance work (such as cutting back vegetation). The section was classified as "completely modified" according to the 2013 overall assessment by the state of Hesse for the implementation of the EU Water Framework Directive. This corresponds to the worst possible condition.
In 2020, the Klingenbach was therefore renaturalized by the Environmental Agency in the area 55 metres after the "Alte Dorfstraße/Klingenbachstraße" junction to "Neue Schulstraße" within the municipal watercourse area. Surveying work in 2010 already showed that the Klingenbach has a width of 3.70 to 4.60 meters. Old grass pavers were removed and a new near-natural section of the stream was created in the upper section with still water zones, gravel banks and natural structural elements. To compensate for necessary tree felling in the course of the construction work, typical riparian trees, shrubs and grasses were planted. Additional nesting aids for bird and bat species have been installed.
Work in the run-up
The planned project presented everyone involved with a difficult starting point. In the town center, the Klingenbach passes through the densely built-up area, a daycare center, infrastructure facilities and various bridge structures. The fact that the Klingenbach in the upper reaches of the Wickerbach system is a third-order watercourse and has a stone crayfish population made implementation even more difficult. This is considered particularly worthy of protection under species protection law and is also on the "German Red List" as a highly endangered species.
Coordination on the renaturation
Through many informative discussions with the Breckenheim local council, the people living directly adjacent to the stream, various authorities and the approval authority, the Darmstadt Regional Council, it was ultimately possible to reach agreement and consensus on the implementation of the renaturation.
Preservation of evidence procedure
Prior to the construction work, an independent expert carried out a preservation of evidence procedure to document existing damage to buildings, structures and safety equipment.
Electric fishing
Electrofishing involves the use of electric current to catch fish. Before construction work began, fish were caught for their protection and released in a safe place downstream. Electrofishing does not harm the animals.
Disinfection
The stone crayfish found in the Wickerbach system is threatened by crayfish plague and invasive alien crayfish such as the signal crayfish. For this reason, disease prophylaxis was a high priority in terms of crayfish protection as part of the renaturation.
Subsidies and costs
The construction and planning costs amount to around 1.1 million euros. As the renaturation section is defined in the Water Framework Directive's program of measures, the project is being subsidized with around 920,000 euros from the Hessian state program "Water and Flood Protection".
Who benefits from this?
The Klingenbach stream can now be experienced again by the local population in many places. The recreational value has been significantly increased by the renaturation work in the local area.
By creating a near-natural stream bed, the Klingenbach is once again passable for fish and other aquatic organisms. Ultimately, the renaturation in the urban area leads to a considerable ecological enhancement of the "water" habitat, especially for the native flora and fauna.
Due to the difficult accessibility and the tight working conditions, all material deliveries and removals had to be carried out in the riverbed. Steel plates, which formed a roadway on the Klingenbach, served as an auxiliary construction.
The Klingenbach now has a significantly increased flow diversity in the area of the stream bed. This means that the current can be either fast or slow and is very varied. This is once again perceptible to observers as a flowing watercourse. Due to the close development, independent development of the bank area is not possible even after renaturation.
It was not possible to rebuild the public bridge over the stream for cost reasons.
The reinforced concrete bridge slab was therefore stored to the side, then reinstalled after completion of the construction work and given a new coat of paint.
Before
The Klingenbach was narrow, the riverbed was barely visible and a narrow section made it difficult to develop the watercourse.
An existing bridge blocked the area and had to be removed for the construction work.
Some of the vegetation on the banks had to be removed from private properties.
During the construction period
Tight space conditions made a temporary construction road made of steel plates necessary.
Construction machinery could only reach the site via the closed footpath next to the daycare center.
Many residents, especially children, followed the work with interest.
Afterwards
The riverbed was significantly widened and now has a greater impact on the townscape.
Stepping stones have replaced the old bridge; a new bridge was built where necessary.
The stream can be experienced again - also for children thanks to the widened areas at the daycare center.
New benches increase the quality of stay.
A new section of water was created by purchasing land; the old course now serves as a still water zone.
Planting
The planting of the renaturation section took place in November 2020. As the renaturation measure on the Klingenbach required the removal of bank planting on private properties, replanting with native shrubs was carried out in consultation with the local residents.
The selection of shrubs and bushes was based on the species protection report for the approval planning. Among others, willow, hawthorn, coneflower and honeysuckle were planted. Among the perennials and grasses, swamp sedge, false cyperus and meadowsweet were planted as a priority.
Floods in February 2021 - a first test
The floods in February 2021 caused many rivers and streams to burst their banks. The much-needed rain, which was lacking in 2019 and 2020, and the current snowmelt caused water levels to rise sharply. The floods also put the new renaturation measure on the Klingenbach to the test.
A conclusion
The safety elements, such as boulders, boulder walls or stone embankments, have not only held up. In fact, new natural structural elements such as gravel banks and deposits have formed in the area between the nursery and Klingenbachstrasse. The mallards at least liked this ...