- 16th November 2018
- Posted by: Sophie Smith
- Category: Projects
The Royal Borough of Greenwich (RBG) commissioned us to carry out a study to investigate potential natural flood management (NFM) interventions in the upper River Shuttle catchment, Avery Hill Park, Greenwich.
The attractive and well-used green spaces of Avery Hill Park and Eltham Park South offer valuable amenity and recreational value. This is reflected in the active friend’s group and local planning policy protection that includes the ‘Green Chain’ and landscape Areas of Special Character and Site of Importance for Nature Conservation (SINC) designation.
The Pippenhall and Eltham Warren Stream are currently little more than drains, piped and straightened through the park, offering little value, whilst areas along the Olympic Legacy path get waterlogged in winter.
The aims of the study were to:
- Better understand the drainage network and flood risk in the upper River Shuttle catchment
- Identify opportunities within Avery Hill Park and the surrounding area for managing flows, reducing the risk of flooding downstream, and ‘day-lighting’ of culverts
- Ensure that any interventions offer multiple benefits and opportunities for local residents, including recreation, health and well-being, education, biodiversity and enhancing the existing historical and conservation value of the area.
The project required a skilled inter-disciplinary team which draws on our wide industry expertise in natural flood management, river restoration, sustainable drainage, landscape design and visualisation, urban hydrology and integrated hydraulic modelling, engineering design and ecology. We also draw on local knowledge from local river modelling studies for the Environment Agency and previous projects for RBG.
We engaged with local stakeholders, including representatives from the Royal Eltham Scouts, Greenwich Wildlife Advisory Group and Friends of Avery Hill Park. The environmental, recreation, landscape and heritage value of the park was assessed.
To investigate the flood mechanisms in the study area and model NFM interventions, a 1D-2D hydraulic model was built in Infoworks-ICM, which can simulate direct rainfall, the river network and sewer network simultaneously. Opportunities and constraints for NFM interventions have been identified and mapped.
Conceptual proposals for NFM interventions have been developed and visualised. These include the:
- Introduction of leaky barriers
- Lowering of banks
- Creation of small meanders, wet woodland and occasionally wetted areas
- Daylighting of pipes
- Access to the watercourses and interpretation boards.
The potential interventions are being discussed with RBG and stakeholders, and several options will be chosen to take forward for options modelling and appraisal.
Our team will ensure that NFM solutions respect the site-specific sensitivities in Avery Hill Park, whilst exploring this exciting opportunity to raise the profile of a forgotten river on the doorstep of extensive urban areas.
A sensitive, well-designed scheme will provide multiple benefits to the upper River Shuttle catchment and Avery Hill and Eltham Park including:
- Work with natural processes to slow the flow from the upper River Shuttle to reduce flood risk downstream in this flashy catchment
- Restore the river to a more natural state and potentially ‘daylight’ some culverted reaches
- Enhance green infrastructure and increase footfall along routes such as the Green Chain Walk
- Improve biodiversity and landscape in two local SINC’s
- Contribute to improving the ‘poor’ Water Framework Directive status of the River Shuttle which is currently failing for reasons including physical modification, urbanisation and invasive species
- Provide recreation, health and well-being for local residents and park users and encourage positive interaction with water
- Offer an inspiring educational resource, providing opportunities for play and education for local children
- Help reinforce the quality and condition of rare fragments of a former rural landscape.