Frankfurt: Floods on the Liederbach – residents fear for their houses

• fromThomas J. Schmidt

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The retaining wall at the Liederbach in Frankfurt has still not been repaired. The residents fear that they will have to bear the risk of further flooding themselves.

Frankfurt – Karl-Otto Müller still cannot assess what will become of his garden. More than a year ago, a flash flood from the Liederbach broke the retaining wall. The owner of the inn “Zum Goldenen Löwen” in Unterliederbach fears: “We residents of the stream must fear for our property.” The city drainage system is responsible for the wall. To this day, Müller and his neighbors do not know if and when they will repair the wall.

But the city of Frankfurt will present its new heavy rain map on Wednesday (October 27th, 2021). This lists all areas in which the residents have to reckon with more than just wet feet. Probably the banks of the Liederbach are also part of the floodplain. Whether this has consequences for the residents is considered on a case-by-case basis.

Frankfurt: A special location causes difficulties with flood protection on the Liederbach

Flood protection needs space. Ideally, retention areas can be designated to absorb the excess of water in the event of heavy rain. For the residents of the Liederbach, however, a special situation applies: the stream rises near Königstein and flows through the Main-Taunus district. Only from the Autobahn 66 does it flow into the Frankfurt district. Only here could the city create security for the residents by setting up seepage areas. However, the area is used for agriculture.

And so the residents of the Liederbach fear that it is they who have to bear the risk of flooding. “The city just wants to renaturalize the stream,” fears Hartmut Neumann. His aunt also lives on the Liederbach, and is also affected by the fact that the wall was partially washed away.

More than a year after the flooding at the Liederbach in Frankfurt, you and other residents are still calling for flood protection: It cannot be that centuries-old buildings are now in retention areas. “As a result of the flood in June 1981, we were divided into a flood area – without our knowledge and against our will – who lived next to the brook. We should just watch our cellars and courtyards fill up every time and not even be able to insure ourselves,” criticized Neumann.

Frankfurt: Wall at the Liederbach damaged – garden could slip into Bach

Müller also finds this absurd. “Renaturation is not an option here,” he says, pointing to the wall. Quarry stones lie in the streambed. During the last flood over a year ago, the wall was damaged in many places along the course of the stream, not just behind his house. “The stream used to run differently. It was only moved here from the village in the 19th century. The houses were here first – the stream came later, ”says Müller.

Accordingly, the approximately two meter high wall supports the property against the stream. It flows – currently peacefully – about two meters lower than the bottom of the property. “How is this going to work in the future without a wall?” Asks Müller. He fears that the garden could slide into the creek bed. Maybe even the foundations of the houses are at risk.

But it is also clear: If the Liederbach is full of water after an extreme thunderstorm, as it was last in August 2020, and this presses through the narrow stream, damage occurs. The stream would have to be “defused” before the city gates, demand residents. At that time it was raining heavily in Kelkheim and Bad Soden – in Frankfurt, however, not a drop fell.

Frankfurt: Liederbach part of the renaturation program

But the small Liederbach had become an unleashed torrent – in the Main-Taunus district, through which the Liederbach, which flows from Woogbach and Rombach at the level of the Königsteiner open-air pool, flows, the creek bed is regulated and lined with basalt blocks. As a result, the flow velocity is very high. There are no designated floodplains between Königstein and Frankfurt.

That could change. Since 2020, the Liederbach has been part of the “100 wild brooks” program of the Hessian Ministry of the Environment. The Urselbach and the Eschbach are also part of this program, which is intended to accelerate the renaturation of the waters, which is already prescribed by the EU by 2027. The country pays 95 percent of the cost.

Frankfurt: Liederbach is to be brought to old bed

Straightening and canalization measures, built around 100 years ago, are to be reversed, and the streams are to be returned to their old bed. The program is intended to support the municipalities in this. New local recreation areas and better species protection are the goal. The experts hope that the reduced flow speed of the streams will improve the cleaning effect.

Floodplains should be formed and the water should be given the opportunity to flood and seep away. The communities through which the stream flows are involved in the Liederbach. The plots must be made available there in order to obtain retention areas. (Thomas J. Schmidt)

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