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Near-natural river dynamics on the River Ems in Lo.. (Ems Niedersachsen)
Near-natural river dynamics on the River Ems in Lower Saxony
(Ems Niedersachsen)
Date du début: 1 janv. 2004,
Date de fin: 30 juin 2008
PROJET
TERMINÉ
Background
The Ems is the most westerly of Germanyâs major rivers and has a total length of 371 km. Since the middle ages, the natural river course and its floodplain have been changed to a largely man-made landscape. Floodplain forest was gradually cleared to create meadows, pastures and, in modern times, intensively-used arable land. Large sections of the river were straightened in the 1930s and riverbank covered with stone embankments to prevent erosion. Dams and other constructions were built to control the river and facilitate shipping traffic. By 2003, the riverâs natural dynamics had been completely altered and only a few elements of the former natural habitats could be found.
A 1999 LIFE Nature project (Emsaue NRW - Ems flood plain: LIFE99 NAT/D/005931) worked to restore the natural river dynamics and alluvial plains along 91km of the river. It reconnected former meanders, removed some small weirs and collapsed bridges, built a bypass around a weir, removed solid embankments and restored natural conditions to tributaries, creeks and drains. Other regionally-funded actions also took place, including the âUntere Haseniederungâ project.
This project covers the middle section of the Ems river and its floodplain, to the north of the area treated by the 1999 project. In the run-up to the project, the beneficiary already invested considerable efforts to prepare the ground. For example, it purchased some key areas needed to develop the Natura 2000 site, while illicit weekend cottages and landing stages for motorboats were removed from sensitive spots.
Objectives
The main objectives of the project were the restoration and conservation of natural river structures and traditional extensively used semi-natural landscapes along 30km of the Ems River and its floodplain.
The plan was to re-initiate dynamic processes by removing the stone blocks reinforcing the banks, to restore sandbanks by morphological riverbed development and to restore natural vegetation to the river and its banks. Works to modify the Listrup weir across the river would seek to re-establish the natural flow.
In the floodplain, the project sought to turn arable land into extensively used grassland, characterised by a typical riverine landscape with moist depressions, temporary pools and ponds, floodwater channels and trenches and sedimentation areas. Planned actions included the planting of indigenous floodplain forest on land which is currently intensively used for agriculture, while existing forests consisting of hybrid poplars and exotic conifers would be changed into woodlands of deciduous trees. Suitable areas would be given back to natural succession and former meanders re-opened.
The project intended to develop collaboration with all stakeholders to find solutions to the potential conflicts between nature conservation, agriculture and water management and mark a further step towards fulfilling the vision of an extensive ecological corridor along the whole of the River Ems. The project therefore aimed to pay considerable attention to public relations and information work.
Results
The project made a useful contribution to the overall objective of creating an extensive ecological corridor along the whole of the River Ems. It purchased land, constructed an important fish bypass, removed stone embankments and restored more natural floodplain dynamics.
The project conducted a status survey of fauna and flora and a hydrological evaluation of the feasibility of measures in the project area. A number of important species were identified on the project area, including black woodpecker (Dryocopus martius), common woodpecker (Alcedo atthis), stag beetle (Lucanus cervus), European beaver (Castor fiber), common barbell (Barbus barbus); Amur bitterling (Rhodeus sericeus); and European bullhead (Cottus gobio).
The project purchased 49.7 ha of land and land-use rights covering 1.27 ha for carrying out restoration work. It had hoped to purchase more land-use rights, but demand for land was very high, increasing prices and reducing the willingness of landowners to sell to the project.
The beneficiary removed stone embankments along 4.01 km to allow the natural development of the river. The most appropriate sections for this were selected in co-operation with the water authority to agree minimised risks to navigation of the river. However it was not possible to remove more bank due to higher than foreseen costs and inability to engage the regional river navigation authority in additional bank removal. The water authority has nevertheless agreed to stop repairs of the embankments which should therefore erode away over time.
The transformation of the weir at Listrup to allow small fish to cross it for the first time since 1828 was the most obvious achievement of the project. After detailed investigation and discussion it was decided to construct a rough ramp with gradient 1:40 on the full 60 m width of the weir. Although the action was more expensive than foreseen and required additional repair work after flooding, it was a good solution and gained co-operation from the water authority and additional funding from an environmental fund. The ramp is a good practice example towards making the whole River Elms passable to fish.
The project was able to plant trees to reforest 5.84 ha. Some initial afforestation with willow plantations was not successful because the willow cuttings were too old. However the process of afforestation through succession extended to an impressive 10.38 ha. Where purchase of land or use rights allowed, the project used surface modelling by removing soil and allocating it to small hills to create a mix of small ponds, moist and dry areas. It created 20.22 ha of floodplain meadows, 4.92 ha of eutrophic tall herbs and 0.36 ha of shallow, temporary ponds.
The project completed the installation of a nature trail and produced accompanying flyers, as well as producing general project leaflets, information boards and a website, and organising an initial public meeting and final conference.
Further information on the project can be found in the project's layman report (see "Read more" section).
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