Amongst others, Tractebel Hydroprojekt is committed to the implementation of the National Flood Protection Program and the Flood Polder Program on the Bavarian Danube. In May 2021, the Federal Environment Agency published the results of an effectiveness analysis of relevant measures (see www.umweltbundesamt.de/presse/pressemitteilungen/geplante-massnahmen-desnationalen). This effectiveness analysis was prepared by the Federal Institute of Hydrology (BfG) as part of a five-year research project. The results show that the planned measures can reduce water levels by 10 to 70 cm over long stretches.
Tractebel Hydroprojekt GmbH (THP) is currently also developing the flood protection concepts for the middle and lower Unstrut on behalf of the Free State of Thuringia. Within the scope of this contract, BfG was supported in the preparation of this effectiveness analysis: THP provided the corresponding evidence for Unstrut and Gera in Thuringia as major tributaries of the Saale and thus of the Elbe. For this purpose, a large-scale 2D model was created (approx. 160 water body km). This model was used to demonstrate the effectiveness of the planned dike rebuilds and dike relocations with the associated gain in retention space. Currently, Tractebel Hydroprojekt is working on the details of these measures on the Unstrut section from the Straußfurt flood retention basin to the Wangen gauge in Saxony-Anhalt.
Furthermore, Tractebel Hydroprojekt is involved in a number of projects of the National Flood Protection Program in different planning stages and with different tasks. These include in particular:
- the reconstruction of polders such as
- The polders Aussig and Dautzschen at the river Elbe
- The polder Elster-Luppe-Aue at the river Weiße Elster
- The flood polder Öberauer Schleife on the Danube
- Improvement of flood protection in the Selke valley
- Flood retention basin Selke near Straßberg
- Flood protection lower Selke
- Implementation of the Kinzig interconnection measure
- Flood retention basin Bad Soden/Salz
- Investigation of the extended retention concept in the Bavarian Main catchment area
For the implementation of the extended retention concept in the Flood Protection Action Program 2020plus, Tractebel Hydroprojekt developed a methodology on behalf of the Bavarian State Office for the Environment (LfU) to identify possible locations for large flood retention basins for the Bavarian Main catchment including an evaluation of their supra-regional effectiveness. This methodology was subsequently further developed and also applied to larger tributaries of the Danube in Bavaria with the aim of evaluating the effectiveness of flood retention basins in the tributary catchments on the Danube in comparison to the effectiveness of the three flood polders Bertoldsheim, Eltheim and Wörthhof, which are disputed in the Bavarian coalition agreement. For this purpose, suitable locations identified by THP for large flood retention basins in the catchment areas of the Lech, Naab and Regen were integrated into a large-scale hydrological model and compared in terms of their effectiveness with the flood polders on the Danube.
As a result of these investigations, in which several offices and universities were involved and whose findings were compiled by the LfU in a synthesis report, it was possible to prove that flood retention basins on the tributary catchments can make a contribution to flood protection on the Danube, but that they cannot replace flood polders. The effectiveness of flood retention basins in the tributary catchments on the Danube is significantly lower than that of flood polders directly on the Danube. The results of these studies were presented to the public in July 2021 by the Bavarian State Minister for the Environment and Consumer Protection, Mr. Glauber, and the synthesis report was published (see https://www.stmuv.bayern.de/themen/wasserwirtschaft/hochwasser/flutpolderstudie.htm). On this basis, the Bavarian government decided to continue planning for flood polders on the Danube with a total of nine sites, including Bertoldsheim and Wörthhof (large variant).
Dr. Stefan Schmid – Weimar