Over centuries human activities have changed considerably the natural and water balance of the Elbe river affecting discharge, various matter cycles and associated ecosystems. These far-reaching measures include the construction of dikes, straightening and engineering the river, construction of weirs, barrages and dams, transfers of water, mining of brown coal, as well as drainage and irrigation of agricultural areas. Furthermore, there are changes due to climate change and various interactions with different measures.
- Coordination: Helmholtz-Zentrum Hereon, Institute of Carbon Cycles
- Partner: Federal Waterways Engineering and Research Institute, Federal Institute of Hydrology
- Cooperations: COSYNA (“Coastal Observation System for Northern and Arctic Seas”), MOSES („Modular Observation Solutions for Earth Systems“), HCDC (“Helmholtz Coastal Data Center”)
- Extension: from Geesthacht, near the beginning of the estuary, into the German Bight, as far as the influence of the Elbe can be observed, so that the Elbe-North Sea Supersite covers freshwater, transitional and coastal waters, including the Wadden Sea
Due to the various uses of the Elbe estuary and the associated areas for living and recreation, for transport, industry and agriculture, there are numerous complex challenges, which are further interacting with climate change:
- Preserve habitats: The Elbe estuary is harbours some highly specialised flora and fauna, as well as some species, which can only be found here. The food web is characterized by a high secondary production, which is used by fish larvae and young fish. The Elbe has the highest fish diversity of all European rivers. However, some fish are dependent to be able to migrate up- and downstream.
- Give more space: Currently, there are 335 km dikes and 17 storm flood barriers, which protect an area over 2400 km², including the city of Hamburg. Therefore the natural retention volume of associated flood plains have been reduced by 8 billion m³.
- Reduce nutrient inputs: Nutrients from the catchment accumulate in the Elbe and lead to a massive growth of microalgae, which are then transported into the estuary. There the microalgae die off and/or are eaten. The leftovers are then degraded by bacteria, which uses oxygen and releases again the nutrients, which contribute to the eutrophication of the North Sea.
- Reduce pollutant inputs: Various pollutants enter the Elbe and are transported with suspended matter, deposit e.g. in the Port of Hamburg and in side arms, and even reach the North Sea. This is a risk for flora and fauna, as well as further human activities.
- Maintain waterway: To allow the passage of big container vessels from the North Sea through the Elbe estuary into the Port of Hamburg and vice versa, the fairway and the harbor basins need to be regularly dredged. Since 2013, the amount of dredged material is continuously increasing. Climate change, river regulation and diking could even further reinforce this trend.