KARLSRUHE/MAINZ (dpa-AFX) - What happens on a large scale at the Jungferngrund shoal in the Middle Rhine is simulated on a small scale around 160 kilometers to the south in a hall in Karlsruhe. There, at the Federal Waterways Engineering and Research Institute (BAW), the river passage has been reconstructed in miniature. The model is intended to help ensure that the mammoth project, which has been planned for decades, is implemented in the best possible way - in the best possible way for shipping and nature, as BAW Director Christoph Heinzelmann explains.

Officially, the project is called the optimization of the navigation channels on the Middle Rhine. The Federal Transport Infrastructure Plan 2030 classifies it as a priority. It is intended to eliminate bottlenecks on the busy Rhine waterway between industrial centers in the southwest of Germany and Europe's largest seaport in Rotterdam. According to Federal Transport Minister Volker Wissing (FDP), who was once also Transport Minister in Rhineland-Palatinate, the project is of "outstanding cross-border significance".

Companies such as BASF have already taken their own measures

As expected, the project has met with approval from the business community in general and the inland shipping industry in particular. "The elimination of bottlenecks on the Rhine must be driven forward so that companies no longer have to bear annual additional costs running into millions," said Karsten Tacke, Managing Director of the Rhineland-Palatinate Business Association (LVU), recently. However, the LVU believes that major projects such as the unloading optimization must be implemented more quickly and with less bureaucracy.

A so-called project advisory board with representatives from the states of Hesse and Rhineland-Palatinate is also involved in the project. In Hesse, the Ministry of Economics and the Ministry of the Environment are calling for the project to be subsequently included in the Federal Approval Acceleration Act. This should speed up lengthy planning and approval procedures. With regard to the cost-benefit ratio of the Rhine project, the Hessian ministries pointed out that the economic damage caused by the low water levels in 2018 alone amounted to five billion euros.

According to the chemical company BASF, which has its headquarters in Ludwigshafen am Rhein, the financial impact of the low water in 2018 amounted to 250 million euros. Since then, BASF has taken its own measures. A digital early warning system for low water has been set up with the Federal Institute of Hydrology, the number of ships suitable for low water has been more than doubled and more use is being made of alternative modes of transport such as rail.

Project is controversial among conservationists

Nevertheless, according to BASF, 40 percent of the transport volume is still handled by ship. On average, 15 barges are handled per day. With regard to the so-called Middle Rhine unloading optimization, BASF stated: "Unfortunately, the implementation of this enormously important project is being significantly delayed by a lengthy approval procedure and a lack of personnel in the responsible authorities."

Transport Minister Wissing referred to the so-called acceleration commission he had set up. It was also thanks to this that a broad-based recruitment campaign was launched to strengthen the project team with engineers and technicians. The processes within the project have been optimized "in order to do the best possible justice to the highly complex issues in the area of conflict between ecology and economy".

The project is controversial among conservationists. The Bund für Umwelt und Naturschutz (BUND) fears a considerable threat to many important habitats, particularly on the banks. "We are calling for the planned funding to be used to modernize the fleet of ships," said Eckhard Genßmann, Chairman of the Mainz-Bingen district group.

Research project in Karlsruhe started in 2015

A position paper by the Nature and Biodiversity Conservation Union (NABU) states that a greater unloading depth requires "oversized ship units at the expense of smaller, better river-adapted ships". The development of the Rhine in the face of climate change is not sufficiently taken into account. "Especially at low water discharges, life in the Rhine will be even more restricted to the navigation channel," it says. The zones with shallow water and tributaries, which are important habitats, would be increasingly disconnected or lost altogether.

To prevent this from happening, the Rhine Waterways and Shipping Authority commissioned BAW years ago to conduct research to lay the foundations for legally compliant planning that balances interests. The Rhine project was launched at BAW at the end of 2015, as Andreas Schmidt, Head of the Inland Waterways Engineering Department, explains. Around ten engineers are now working on this project at BAW.

Roughly speaking, it concerns the section of the Rhine from Budenheim near Mainz in the south to St. Goar in the north. According to the Federal Waterways and Shipping Administration (WSV), around 50,000 cargo ships (as of 2021) travel along this stretch every year, transporting almost 60 million tons of cargo. According to the WSV, forecasts predict an increase to more than 75 million tons in the coming years.

Inland navigation association speaks of a "real pinhole"

However, the consistently guaranteed fairway depth there is only 1.90 meters below the equivalent water level. This is a low water level that is only reached or fallen below on around 20 days per year. Upstream and downstream, it is 2.10 meters, i.e. 20 centimeters more. That doesn't sound like much, but it's worth a lot of money. An additional 20 centimetres of water depth would allow up to 200 tons more freight per ship, says Thorsten Hüsener from BAW's Middle Rhine project team.

The Federal Association of German Inland Navigation, based in Duisburg, describes the limited fairway depth in the Middle Rhine as a "real bottleneck". If the unloading optimization is implemented, ship transports will be easier to plan and carry out even at low water. "This is important, as the raw material-intensive industrial sites depend on reliable deliveries by inland waterway."

Numerous shallows are to blame for the shallower navigation channel in the Middle Rhine. The unloading optimization project focuses on the six most critical ones. These are the Jungferngrund, which was recreated in Karlsruhe, the Geisenrücken, the Lorcher Werth and the Bacharacher Werth in the rocky, narrow valley north of Bingen, as well as the Kempten fairway and a point near Oestrich-Winkel in the sand and gravel section of the Rhine in the Rheingau.

Project manager: There are only individual solutions

The large-scale project to optimize dumping on the Middle Rhine aims to increase the depth of the fairway here to 2.10 metres throughout

- through the most selective and environmentally friendly interventions possible, which

at the same time must not worsen the level of flood protection, as Sven Wurms, head of the project at BAW, explains. "There are only very individual solutions," says Hüsener. "No two sections of the river are the same."

The BAW uses computer models and the Rhine model to see where sediment can be carried into the navigation channel by the current and become a problem. They then examine how, for example, a higher current speed and thus a lower deposition of sand and gravel can be achieved or how the transport in the water can be directed.

Possible solutions include the construction of groynes, structures projecting transversely into the river, structures running alongside the river, ground sills on the river bed or the filling of scours, depressions in the river bed. In the stony section of the Rhine, it will also be necessary to cut away rock at certain points on the river bed, taking into account the properties of the respective rock type, from soft clay slate to hard graywacke.

Jungferngrund is a particular challenge

The situation at Jungferngrund near Oberwesel is particularly tricky, as project manager Wurms says. Here, the Rhine makes a 90-degree bend, ships need a fairly wide channel for their maneuvers and the flow conditions along and across the course of the river are complex, partly because of the gravel bank of the same name and a rocky island called Tauber Werth.

The gravel bank as an important habitat for animals and plants must not be damaged by any changes. It must be ensured that the tributary between the gravel bank and the right bank of the Rhine is still flowing, not silted up, as Wurms explains. All possible variants are simulated on the Rhine model at a scale of 1:60 in length and 1:50 in height.

For the model, the river bed with all its rock crevices and ribs was

-and ribs made of 170 concrete tiles, it took a year before the model was fully

was fully operational. Instead of sediment, plastic granulate is transported here by the model current, in different sizes and with different material densities in red, white and yellow. Conceivable hydraulic structures are built to scale and tested.

Federal institute also to evaluate

According to current findings, the variant with individually shaped ground sills performs best, as Hüsener says. It is comparatively successful in carrying the majority of the sediment in the water to the section near the world-famous Loreley with depths of up to 19 meters and keeping the impact on the environment to a minimum.

The search for solutions that take many factors into account is almost "squaring the circle", says BAW boss Heinzelmann. This also explains why the project is likely to take many more years - not least because of the pending and time-consuming planning approval procedures. The Rhine model in Karlsruhe is likely to remain in place for a long time, and BAW will continue to evaluate the measures taken after the construction work has been completed./chs/DP/zb

--- By Christian Schultz, dpa ---