It was a hydraulic engineering project to promote Hamburg's harbour industry that heralded the unexpected beginning of a golden era for the tributary of the Elbe that flows into the Norderelbe at km 615.05 (RU). In 1952, the Tatenberg lock was completed about one kilometre from the estuary, making the Dove-Elbe tide-free from then on. The lock was built to achieve an even distribution of water between the North and South Elbe, as the Dove-Elbe-retten.de initiative has discovered on the basis of historical sources. This water distribution was necessary so that modern tankers could supply crude oil to the oil industry based in Harburg. Until now, large tankers often only reached Harburg on the tidal wave.
While the ships in the Süderelbe had more water under their keels - at least for a while - the Dove-Elbe developed into a high-quality ecosystem with clean water, a diverse fish population, rare animal species such as beavers, kingfishers and river mussels as well as a unique nature reserve (Die Reit). What's more, the Elbe tributary, which is navigable over a length of 18 kilometres, has been transformed over the years into a water sports and leisure paradise. It was a time for pioneers.
Gradually, harbours, shipyards, boat hire companies and other nautical businesses, and even a shipping line, were established. In 1986, the Hamburg-Allermöhe water sports centre for rowing and canoeing was opened at Dove-Elbe-km 15.20 (RU). It has a 2000 metre long regatta course that is suitable for international competitions. At its edge, on the Allermöher Deich, is the state rowing and canoe racing training centre, which is part of the Hamburg/Schleswig-Holstein Olympic training centre. The centre cost two million marks at the time and further investment is now planned.
Today, the Dove-Elbe is considered Hamburg's largest contiguous water sports area. According to the Dove-Elbe-retten.de initiative, it is home to 15 marinas and boat storage facilities with around 1,800 moorings and winter storage spaces for commercial providers and water sports clubs. 30 service companies make their living there, two sports boat schools use the protected waters, as do 15 rowing, motorboat and sailing clubs with youth training programmes and six boat hire companies (canoes, paddle boats, pedal boats, electric boats, motorboats). Several fishing clubs also indulge their passion here.
The special character of the Dove-Elbe natural and living environment - characterised by the harmonious coexistence of the people who live, work, spend their leisure time or seek relaxation there - has long since spread beyond the borders of the Hamburg metropolitan region. This is reflected in Tatenberg Bay, especially on balmy summer days and evenings. Whether in a packet or lying alone at anchor, the boating folk in the "Pensioners' Bay", as it is known among insiders, relax and unwind together.
The tourist importance of the Dove-Elbe as a local recreation area on land and water is particularly evident during the ongoing coronavirus pandemic with its restrictions on long-distance travel. Thousands of Hamburg residents discovered the attractiveness of the Vier- und Marschlande district of Bergedorf during this time. Thanks to its water quality, the tributary of the Elbe serves as a "watering can" for Hamburg's largest vegetable and flower garden as well as a watering place for horses and livestock.
While the Dove-Elbe began a happy and beneficial life of its own for its neighbours and residents after the separation from the Tidal Elbe, the main river continued to go downhill. Due to a constant stream of new generations of container ships with greater draught and Hamburg's competition with other port cities, the Elbe was lowered four times after the construction of the Tatenberg lock: from 9.50 metres below sea level (SKN), which corresponds to 11.40 metres below sea level (NN), to 14.90 metres below SKN and 16.80 metres below NN in 1999.
It was the eighth deepening of the Elbe since 1818 and the ninth is currently underway, having cleared the final legal hurdle in June 2020 after one of the most protracted procedures in German legal history. The aim is to deepen the navigation channel to 15.90-17.10 m below sea level to allow ships with a draught of up to 13.50 m to access the Port of Hamburg regardless of the tide and up to 14.50 m depending on the tide. However, the repeated deepening of the harbour has now clearly had fatal consequences.
"The current conditions of the Elbe have changed drastically," states a background paper from the "Lebendige Tideelbe" (Living Tidal Elbe) action group, which is made up of the environmental organisations BUND, NABU and WWF. "There are extreme currents in the fairway and slower currents in the side areas. The result is increasingly hostile conditions in the river and a simultaneous silting up of the bank zones. The typical side arms of the Elbe estuary are in danger of silting up and being lost for good."
The dredging also changes the water levels in the river. "At low tide, former shallow water areas now dry up. Aquatic plants with associated species communities lose their habitat. And the force of the tides is also thrown out of balance. At high tide, the water pushes more strongly upstream and washes sediment and silt from the North Sea far into the river, its side arms and neighbouring harbours. At low tide, the water flows out more slowly, meaning that material carried in can no longer be removed sufficiently. The river silts up. The process is called tidal pumping," say the environmentalists.
Hamburg, Lower Saxony, Schleswig-Holstein and the federal government launched the Tidal Elbe Forum in 2016. Its task is to "find solutions that positively change these unfavourable tidal dynamics - and at the same time create more original tidal habitats on the Lower Elbe", as the Hamburg Ministry for the Environment, Climate, Energy and Agriculture explains in a press release. The focus was on measures to give the river more space. The forum sounded out a total of over 20 project ideas along the tidal Elbe. As part of a pre-selection process, five measures were proposed for in-depth consideration. Separate feasibility studies were commissioned for three of these: for the reconnection of the Alte Süderelbe, the Haseldorfer Marsch and the Dove-Elbe to the tidal Elbe.
The Forum Tideelbe presented the eagerly awaited results of its four-year investigation on 30 September 2020. According to the results, all three measures are technically feasible, but their effects differ:
- A reconnection of the Alte Süderelbe would achieve the greatest hydrological effectiveness in the tidal Elbe in comparison.
- A reconnection of the Haseldorfer Marsch would have the potential to enhance the ecological value of the tidal Elbe to a particularly high degree.
- A reconnection of the Dove-Elbe would have a positive local effect on tidal dynamics, primarily in the area of the Norderelbe.
According to the feasibility study for the Dove-Elbe, the desired reduction in tidal range in the Elbe is greatest in the area of the mouth of the Dove-Elbe at around 10 cm, but the tidal range is only reduced by around 2 to 3 cm in the area of the Port of Hamburg. While the focus of the Tidal Elbe Forum may indeed be on ecologically upgrading the battered river, this is - as it was 70 years ago - a hydraulic engineering measure in favour of the Port of Hamburg, which is struggling with an increasingly dramatic silt problem.
But this time they are threatening a paradise. The return of high and low tide would probably mean the end of the cultural landscape east of the Tatenberg lock and its intact, high-quality ecosystem, and irreparable damage not only to large parts of the nautical industry located there. Planning details for the realisation of such a scenario are revealed in the 174-page feasibility study entitled "Impacts of connecting the Dove-Elbe to the Tidal Elbe and effects on stakeholders", commissioned by the Hamburg Port Authority from BBS Greuner-Pönicke in Kiel. Büro Planung & Moderation, Hamburg, was brought on board to involve the stakeholders (entitled parties, affected parties), while the Lübeck engineering firm Dr Lehners + Wittorf handled the water management aspects.
Two options for reconnecting the Dove-Elbe to the tide were analysed. The so-called basic variant focussed on the section from the Tatenberg lock (km 19.06) to the Krapphof lock (km 8.20 RU). However, it soon became clear that its implementation "would lead to serious changes in almost all relevant areas".
This is one of four points that the study cites as examples: "Loss of the basis of existence, e.g. for the Allermöhe and Neuengamme shipyards, the Bergedorf shipping line, the Bergedorf rowing club, the Möller sports boat harbour and a reduction in the attractiveness of all shipyards, water sports clubs, boating schools, boat rentals, etc. due to a severe restriction of accessibility due to the changing water levels". As the basic variant would not be feasible "without the creation of an almost completely new usage and landscape structure on the Dove-Elbe", the Tidal Elbe Forum initiated the discussion and planning of an "optimised variant" with the aim of reducing the water management, environmental, ecological and stakeholder-related conflicts of the basic variant. As far as the affected yacht clubs, water sports associations, harbour operators, shipyards, boat hire companies and boat schools are concerned, this also failed with the new variant, to put it bluntly.
With this variant, the Dove-Elbe is only available for the tidal range up to the Allermöher Kirchenbrücke (km 14.00), i.e. in a 5 instead of 11 km long section. The optimised variant also entails massive, in some cases even more serious changes. It envisages the construction of a central lock 120 metres long and 12 metres wide at the Kirchenbrücke bridge, not far from a large bird breeding meadow, to keep the upper reaches of the Dove-Elbe tide-free. Flanked by a fish pass on the right-hand side and a sluice structure for draining the upper reaches on the left.
In order to achieve the maximum effect when opening the Dove Elbe for ebb and flow, the tidal range is adjusted in the optimised variant. While the upper tidal limit of +0.90 m NHN (mean sea level) is retained, the lower limit is lowered to -1.20 m NHN. This increases the water level fluctuation to 2.10 m while at the same time increasing the tidal volume.
In order to make better use of the available tidal volume, the barrage at the Tatenberg lock is to be widened by 7 metres to 32 metres and deepened by 1 metre to -3.60 metres above sea level. A high-water pumping station is also planned. Due to the strong currents when the tide comes in and goes out, it is necessary to install flow deflectors in the vicinity of the barrage. The latter would have serious consequences for the Möller marina, which would lose or have to relocate part of its jetty.
To ensure that the Dove-Elbe is navigable even at low tide and that harbours and businesses remain accessible, the section between Tatenberg Lock and the regatta course and above the regatta course to the middle lock is to be dredged to a bed depth of -3.50 m NHN. "This was determined taking into account the lowest tidal water level (-1.20 m NHN) to ensure navigability. Another positive effect of the deepening is the increase in the usable tidal volume and reduction in flow velocities," the feasibility study states.
According to the study, the infrastructure will be adapted to the changing water levels to ensure harbour operations. This means that the existing fixed jetties will be dismantled and replaced by floating jetties. This affects a total of around 2.5 km of jetties in the Möller marina, Tatenberg marina, Moorfleet marina and the jetties on the north bank above the Tatenberg lock.
This is particularly bitter for the Hamburger Yacht-Club im ADAC e.V., which is based in the Tatenberg marina and only renovated its main jetty (D) with 40 berths four years ago. Despite a high level of in-house labour over twelve weekends in the winter of 2016/17, this represented a six-figure investment for the club. The ultra-modern, fixed jetty with non-slip plastic grid panels would be unusable in a future tidal harbour. The Dove-Elbe-retten.de initiative, which those affected on land and water founded in March 2019 to defend their area - we reported on their actions several times - fears that the conversion of the harbours and jetties will result in the loss of at least a third of the berths.
According to the expert opinion, the water-side dredging work will result in high excavation depths, particularly in the harbour area, as the previously embanked banks will be removed and secured with sheet piling. Between the Tatenberg lock and the regatta course and between the regatta course and the centre lock, an average of 1 m to 1.50 m of soil will have to be removed. A total soil volume of around 520,000 m3. In addition, there will be land-side excavation areas for the development of tidal biotopes. In the vicinity of the banks of the Dove-Elbe, up to 3.50 metres of soil will be removed. Total volume: 86,000 m3.
In the course of reconnecting the Dove-Elbe to the Tidal Elbe, it is also planned to reopen the Eichbaumsee to the Dove-Elbe with a bottom height of -3.50 m NHN at the breakthrough. This will result in an additional 44,000 m3. If the creators of the feasibility study have their way, the entire 650,000 m3 of dredged material could be relocated to the Eichbaumsee, which is around one kilometre long and 280 m wide. It would then be only
13 metres instead of the currently assumed depth of just over 5 metres.
The feasibility study reveals one of its gaps in this point - the relocation of the excavated soil - which is so important for the realisation of the project. "The pollutant load of the existing soils is not known and must be checked accordingly." The authors of the study themselves appear to be sceptical here. In the analysis of the ecological impact of the optimised variant, the following is seen as one of the disadvantages: "The excavations also affect soils worthy of protection and flushing areas with suspected pollutant contamination."
Wolfgang Schnorrenberg, Chairman of the Hamburg Yacht Club (HYC) and one of the spokespersons for the Dove-Elbe-retten.de initiative, is not surprised. "We have concerns that the deepening of the riverbed by dredging will push through layers of soil that have been deposited with highly toxic harbour silt since the dredging in 1922/23. It is undisputed that the authorities are aware of this. The HYC was warned years ago by the district authority not to expand our air bubble system on jetties E and F because they feared we would stir up the highly toxic silt deposited there."
There is also a need for clarification elsewhere: What impact will the re-authorisation of the tide in the Dove-Elbe have on tourism and local recreation and the associated jobs? How will the water quality of the Dove-Elbe develop under the influence of the tide? Pollutant input from suspended matter from the Elbe? Further investigations would be required for all of this if the project "Connecting the Dove-Elbe to the tidal Elbe" is actually pursued further. According to an initial cost estimate, the realisation would cost almost 500 million euros.
Whether it is worth it to completely change a cultural landscape that has grown over decades for two to three centimetres less tidal range in the port of Hamburg is now up to the 123 members of the Hamburg Parliament to decide. The activists of the Dove-Elbe-retten.de initiative - and not just them - are fervently hoping for one thing: mercy!
