Project shows how nature-based solutions can be used to tackle flooding and clean polluted water

10 August 2020

The partnership project transformed a waterlogged greenspace into a wetland oasis for both people and wildlife.

The project completion coincides with the Met Office publishing their annual report which stated that climate change was ‘driving UK’s extreme weather’ with northern England suffering from its ninth wettest year in a series from 1862.

Many experts believe that the UK will continue to face multiple flooding threats, many of which are exacerbated by climate change including summer flash floods caused by extreme downpours and extensive autumn and winter river floods caused by persistent heavy rain and storms.

Utilising a Sustainable Urban Drainage System (SuDs) the green space of Dale’s Brow in Salford, Greater Manchester which is vulnerable to flooding was used to show how natural solutions can address issues of not only surface water flooding but pollution.

Pictured below the space before the intervention:

The space was transformed with the installation of two swales (a sunken, marshy ditch), the creation of a new 64sqm wetland area, a 40m long beech hedge as well as hundreds of new plants and trees.

The system will work as rainwater running off the road will be diverted away from the sewers into the swales. In heavy rainfall events the rainwater will travel along the swales and into a temporary wetland area.

When the swales and wetland area are full, the water will overflow back into the water course via a pipe connection in a clean and safe condition.

The swales and the wetland area will contain a variety of different vegetation types able to cope with wet conditions. Microbes in the soil and vegetation will trap and help to break down any pollutants into harmless compounds.

The project has a number of benefits; not only helping to reduce surface water flooding at a local level but it also eases pressure on the sewer infrastructure as well as providing costs savings with respect to water treatment and reduce the likelihood of pollution incidents in watercourses from overflowing sewers.

As well as the nature-based interventions, other measures include a new footpath, tree planting and the creation of low maintenance ‘biodiverse’ planting areas ensuring the space can be benefit both local people and planet.

Below - artists impression of the newly designed space:

The University of Salford will monitor the quantity and quality of surface water entering and exiting the site to determine the amount of water diverted away from the combined sewer and the ability of the SuDS features to remove vehicle-based pollutants.

Bryan Cosgrove, Resilience Co-ordinator at City of Trees comments; “This project demonstrates that there are natural ways of reducing flooding and cleaning our water, beyond traditional hard engineering solutions.”

He adds; “We hope that this type of solution becomes the norm and not the exception.”

Adam Chapman from the Environment Agency comment; “This project shows the value of investing in Green Infrastructure to tackle the issues of today and tomorrow. Through a partnership of local key players, this land has been enhanced, enriching the local environment and providing multiple benefits with respect to flood risk, water quality and amenity value.”

Cllr Derek Antrobus adds; “Climate change poses the biggest threat to our future and so we must act now to increase our resilience to further extreme weather events. This project shows how we can manage our water sustainably whilst improving green spaces for local people – which is especially crucial at this time”.

The project has been delivered in partnership with City of Trees, Salford Council, The Environment Agency, United Utilities and the University of Salford. It has been funded by Salford City Council, The Environment Agency and Natural Course. Wardell Armstrong were the Landscape designers and Landscape Engineering the site contractors.