River Restoration Project

Arnos Park - Pymmes Brook

River catchment: Pymmes Brook, Lee
Grid reference: TQ2950892757
Project length (m): 1000
Start Date: 2008
Status: Planned and designed

Site Background

The Pymmes Brook is a clay-based river in a high-energy river catchment. Sections of the Pymmes Brook that resemble naturalised river forms exhibit characteristic features of a high-energy system, meanders, small meander cliffs, gravel bars and pool. The river through Arnos Park has been resectioned, constricted, has a concreted lining (in places) and contains a number of weirs which impound and stagnate the water, resulting in extremely poor water quality (GQA class E) as well as a lose of natural morphological features. Arnos Park has been designated as SINC Borough level 2 for it ancient woodland and damp grassland, the pymmes runs through the middle of the park and currently provides little ecological value, while the potential of the river remains huge. A Flood Risk Management project is being investigated for wider benefits and includes potential significant enhancements to this section of river.

Motivations

Habitat, Flood risk management, Fisheries, Access and recreation

Objectives

To re-establish natural geomorphological features within the Pymmes Brook, including the creation of natural instream features, natural banks, wet berms, potentially wetland scrapes and wet grassland i.e. reconnecting the river with the surrounding habitats, its floodplain.

Potential work:
(Include feasibility and further needs study)
The First step would be to carry out a feasibility study of the Pymmes though Arnos Park, including the surrounding landscape, defining the potential habitats which could be create and where. This would also give an idea of the cost and time scales involved. Depending on the outcomes of the feasibility study, a topography study of the area maybe needed if the its decide that wet scrapes and marshy areas should be created, thereby defining the works that would be needed to create these areas.

The NE Thames River restoration document also highlights this area as potential for full river restoration.
The works should include the removal of all impounding structures and artificial embankments. Once this has been completed there should be a low flow channel created which meanders its way along the natural course of the Pymmes (may not be the current course, decided by a topographical study). Outside, the low flow channel a peak flow course should be created, this should include wet berms and setback Flood risk managements to allow the river to naturally flood. These areas should contain back waters, wet berms, natural erosional cliff faces and wetland scrapes, which would significantly improve the biodiversity value of the area and the amenity value to local residents.

Main Funders

EA - grant in aid, potential contributions from LA’s and GLA

Non-funding Partners

London Borough of Enfield, London Wildlife Trust, EA, GLA

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