The majority of Germany's rivers have been widened and straightened in recent times, and this has had a significant impact on the fish, plant and animal communities in many watercourses.
We are attempting to restore the original river beds and banks by rewilding these adjusted river courses. For us, this is more than just a compensatory measure. When we upgraded the Rhine Valley Railway in Baden-Württemberg, we improved conditions in the Elz, Kinzig, Dreisam and Schutter rivers and created species-appropriate habitats for fish whose numbers have declined, such as Atlantic salmon, chub, bleak and dace.
Fish ladders to help swimming
Fish like to return upstream to their habitual spawning grounds to lay their eggs. Often, however, their route is blocked by dams and waterfalls that were built in the past. To enable the fish once more to carry on with their natural migration, we build fish ladders in the water.
On one section of the Schutter, for example, we built a fish ladder that comprises several basins and thus has a reduced gradient. Now the fish can better overcome the height difference of more than a meter and species that are more vulnerable in currents can climb with ease.
"Fish nursery" in the Nidda River
During work on the tracks between Frankfurt West and Friedberg, we rebuilt the bridge over the Nidda River in Bad Vilbel. Gravel banks had to be built up for the construction work. After finishing the work, we redistributed the gravel in the riverbed to create new spawning grounds and shallows for fish species such as barbel, roach, bleak and dace.
We also built a groyne in the river, a kind of dam that directs and regulates the river's flow. That results in areas where fish can rest during the spring migration to their spawning grounds.
Restoration in Praunheim and Eschersheim
An impact on the environment was unavoidable during construction of the new S-Bahn tracks in the Frankfurt West and Friedberg project, so we're creating habitats elsewhere to compensate. In Praunheim, for example, we're working with our partners to restore an old weir in the Nidda by converting the existing fish ladder into a ramp, strengthening the flow along the riverbed. And in Eschersheim, we're deepening and widening a 400-meter stretch of the Urselbach stream to improve its flow. With our restoration efforts, we're making a lasting contribution to biodiversity by ensuring that more fish can establish themselves there.