Adaptation of the River Weser

Good accessibility of German seaports is of primary interest to Germany as an industrial nation. The extension of the fairway in the Weser estuary has been defined as a priority requirement in the German government’s Federal Transport Infrastructure Plan 2030. The aim is to facilitate the management of marine traffic in the tidal area where vessels will increase in size in the future. The fairway extension will remove bottlenecks and access to the seaports of Bremerhaven and Brake will be improved as a result. Consequently, conducting a planning procedure for the extension project is of high priority and urgency. This planning procedure, which has been initiated by the WSV and for which the BAW provides expert opinions, is referred to as adaptation of the River Weser.

The plans to deepen the fairway by approximately 1 m and to widen a section of it will affect the marine environment: impacts reach from the intrusion of North Sea salt water further up into the estuary to changing sedimentation and erosion patterns on the sea bed and higher loads on the banks due to ship-induced waves. The BAW provides predictions of the impacts of the fairway extension with respect to all of these areas and advises the WSV on the planning, construction work and subsequent evidence procedures. The impact predictions are mainly based on numerical simulation models of the River Weser. However, specific field measurements and systematic studies in scaled physical models are also employed. The changes predicted by the BAW are then evaluated for their impact on the environment by other experts, and compensation and replacement measures are specified in the planning procedure.

Environmental law requires the use of state-of-the-art scientific methods to ensure that the BAW’s predictions are highly reliable for measures such as the adaption of the River Weser, which affects the ecologically valuable dynamic system of an entire estuary with its adjoining natural reserves. In some cases this means that the BAW has to drive scientific development by conducting its own research and making this visible in its expert opinions.

Literature:
Kolb, P., Zorndt, A., Burchard, H., Gräwe, U., and Kösters, F.: Modelling the impact of anthropogenic measures on saltwater intrusion in the Weser estuary, Ocean Sci., 18, 1725–1739, 2022. https://os.copernicus.org/articles/18/1725/2022/