aerial view of a green bank structure with riparian forest
Above water

Kreetsand: A new habitat for the Elbe is being created

The influence of the tides on the Elbe is enormous – and is increasing over the years. To mitigate the effects of the tides, which lead to silting up of the harbour and the shipping channel, we are creating a new floodplain in the east of Hamburg: Kreetsand.

aerial view of a green shore structure with a temporary jetty where a transport barge is moored
On the eastern side of the Elbe island of Wilhelmsburg, we have developed the tidally influenced shallow water area of Kreetsand to create new flood storage areas.
aerial view of a water surface and a tongue of land, a dredger dredges mud into a lorry
This flood storage area for 1 million cubic metres of tidal volume helps to reduce the so-called tidal pumping effect and thus the amount of sediment.

The tidal range of the Elbe is around 3.80 metres at the water level measuring point in the port. This was different 70 years ago, when it was only 2.50 metres. There are various reasons for this: The natural widening of the Elbe estuary, which results in stronger tidal currents in the Elbe, the rise in sea level due to climate change, blocking of tributaries, dyking of side areas, but also the adjustments to the navigation channel have favoured this effect. As a result, the tidal current that pushes the water into the harbour develops more force and washes more sediment upstream. The result? Harbour basins and fairways are silting up faster.

graphik shows the habitat zones of a tidal river bank
The flora and fauna on the banks of the Elbe also live to the rhythm of the tides and are well adapted to alternating dry spells and flooding. These tidal freshwater areas are particularly rare and are therefore often protected.

To counteract this, we have developed an innovative concept - this includes the creation of the shallow water area Spadenlander Busch / Kreetsand on the Norderelbe. On a 30-hectare area in the east of Wilhelmsburg that was previously wasteland, we are creating a new, natural bay that fills with water at every flood. Due to the size of the area, this has a dampening effect on the tidal range, because every time the shallow area fills up at high tide, energy is withdrawn from the tide and the current is calmed. At low tide, the outflowing water of the Elbe is fed from the area and supported. In the long term, such measures are intended to reduce sediment transport, as a lower tidal range or weaker tidal current brings less sediment with it.

aerial view of a naturally designed green bank structure
With the Kreetsand area, we are realising the first major river engineering project on the tidal Elbe. Around 30 hectares of new flood storage area have been created. This will create ecologically particularly valuable tidal Elbe habitats such as this tidal flat, home to the rare hemlock water fennel.

The new Kreetsand flood storage area is a first building block towards a more sustainable development of the Tidal Elbe: In this way, the river is given back space that has been lost in recent decades due to dykes, barriers, construction work and siltation. The new shallow water area will also provide space for flora and fauna typical of tidal areas. Around two million cubic metres of soil have been excavated in order to make the best possible use of the effect on tidal attenuation and to ensure that there is still enough water for fish and other creatures even at extremely low tides - more than six times the volume of Hamburg's Inner Alster. In future, the riparian forest will be able to spread here and the Elbe water dropwort, which only grows in the tidal Elbe, will be able to establish itself.

In this project, nature conservation and business go hand in hand: on the one hand, we are securing access to the Port of Hamburg in the long term through projects such as Kreetsand, and on the other, we are creating new tidal habitat for nature.

By the way: we have completed the Kreetsand shallow water area by the end of 2022. Click here for the article.

 

FAQ on the Hamburg floodplain Kreetsand

The most important questions and answers at a glance

 

Floodplains are areas that specifically absorb water during high water or floods. In Hamburg, they play a key role in minimising the effects of the tide and relieving the Elbe river basin.

 

 

Kreetsand serves as an additional flood storage area that absorbs and releases water at each tide. This reduces the flow energy of the Elbe and weakens sediment transport. It is also an important habitat.

 

 

The tidal range of the Elbe has increased significantly in recent decades. New flood storage areas help to compensate for this effect and limit the increasing siltation of the harbour and navigation channels.

 

 

The area is located in the east of Hamburg on the Elbe island of Wilhelmsburg on the Norderelbe, in an area that was previously barely used.

 

 

When large, flat areas fill up at high tide, energy is extracted from the flood current. This calms the current and reduces the force with which sediments are transported upstream. At low tide, the water is slowly released again, thereby improving the return transport of sediments.

 

 

Kreetsand combines hydraulic engineering goals with nature conservation. It creates retention space for the Elbe and at the same time new habitats for tide-dependent plants and animals as well as refuges for fish. The oxygen supply to the Elbe is also positively influenced.

 

 

These habitats have become rare, as many shoreline areas have been diked or cut off. They offer optimal conditions for specialised species that are adapted to changing water levels.

 

 

Typical tidal habitats such as tidal creeks and shallow water zones are being created in the area, providing refuge and spawning grounds for rare plant species, fish and invertebrates. These include, for example, the hemlock water fennel or fish such as the protected finch or asp. The white-tailed eagle also uses the area as a resting and feeding area.

 

 

Kreetsand is the first major building block in a long-term strategy to give the Elbe more space again and to develop the tidal Elbe more sustainably.

 

 

By reducing sediment transport, harbour basins and navigation channels tend to remain usable for longer. At the same time, the ecological condition of the river is improved - a win-win situation for both sides.

 

 

The shallow water area was completed at the end of 2022 and has been fully tidal since then.

 

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