Saturday, 15 September 2012

Little Ouse river works

If you have visited the Heath in the past week you may have noticed some practical works being undertaken on the Little Ouse; the river that marks our Northern boundary. A project under the Environment Agency (EA) has been targeting restoration work on rivers across the country this year. Working in partnership with conservation charities and other countryside management organisations, including Suffolk Wildlife Trust, the EA targeted the Little Ouse to host the first major river restoration work undertaken in Suffolk. This was partly due to land alongside the river being owned or managed by many of the partners in the project, and the river will be used as a demonstration of what can be achieved in our water ways throughout Suffolk.

Why was restoration work needed?
Pre-restoration the Little Ouse had been heavily modified over time by mans intervention, such as continued dredging of the water course and possible historical use as a travelling route for small trade boats. This had left the river very straight and deep sided with a poor flow, resulting in the clogging of vegetation and the degradation of species habitats and diversity. (See photo right) A full programme of surveying has been undertaken previous to this work to ensure areas of the river that may have been sensitive to work, such as water vole habitat, were highlighted.

Explaining the practical work:
The aim of the project was to return the river to it's natural state by restoring features such as pools, riffles and meanders. Manually creating these features was achieved with a mechanical digger (see photo right), and although it may have looked fairly destructive at first, the simplicity of the work is very effective. Vegetation was cleared along the river to allow digger access, which then moved upstream along the bank clearing out deep pools on one side of the meander, and depositing the material on the other side.

This action re-creates the natural curve of the river within the channel and is partnered by the deposition of rocks and debris between meanders to create natural 'riffles'. Riffles are where the water increases it's flow where it is narrowed over rocks creating a 'babbling brook' effect, increasing oxygen levels in the water and increasing water quality.

Diagram above showing the natural meander recreated within the channel
It won't take long for the river and it's biodiversity to adjust to this re-naturalisation; vegetation will quickly take root in the deposited debris creating attractive habitats for freshwater invertebrates, whilst fish will use the deep pools and create hunting areas for Kingfisher and Otter.

Photo showing the new natural meanders within the long channel
Four days after the work had finished, there were already reports of more regular wildlife sightings on the river; the increased flow has cleared out any muddy debris or dead vegetation and the river already is visibly more appealing. If you get a moment in the next couple of weeks it is well worth a trip to see the difference!
For any more information or queries please don't hesitate to contact Samantha Gay the People and Wildlife Ranger:

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