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Posted By:
Fran Tute
Communications Officer
Brighton & Hove City Council has protected communities from flood dangers with a street-level solution. It is using Sustainable Urban Drainage Systems (SuDS) – patches of trees, plants, and marshy land that soak up excess water. In urban environments, even small SuDS and green areas do a lot to lower flood risk.
The authority has worked with communities and experts to deliver its climate adaptation programme, in which SuDS play a key role. As well as tackling flood risk, they can help to increase biodiversity and protect local water resources. The council has pioneered its SuDS innovation with a pilot scheme at Carden Avenue, in the north of the city. The scheme is an example of how measures installed over a relatively small area can help to reduce flood risk in the wider catchment area.
“We’ve seen flooding increase in our city with more coastal storms and warmer, wetter winters, damaging homes and businesses. The Carden Avenue SuDS scheme is an example of how collaborative working with local and international partners and residents can build resilience, protect homes and respond to the threat of climate change happening now. We are taking forward the learning from this pilot to inform a strategic approach to scale up actions for net zero and develop a council-led programme for climate adaptation in the city.”
– Councillor Trevor Muten, Chair of Brighton & Hove’s Transport & Sustainability Commitee.
Brighton & Hove is one of the top ten clusters most susceptible to surface flooding in England. Severe rainfall in 2014 damaged properties in some parts of the city. Climate change is set to bring more volatile, and more frequent, extreme weather in the years ahead.
As part of its strategy on climate adaptation, the council partnered with the EU to deliver its local SCAPE (Shaping Climate Change Adaptive PlacEs) project. SCAPE partners in Belgium, the Netherlands and England developed and tested ‘Landscape-Led Design’ solutions for water management in places at high risk from flooding. In Brighton & Hove, this included using technical analysis, expert opinion and local knowledge to determine which flood-prone parts of the city could benefit from SuDS upgrades.
Carden Avenue was selected as the pilot area. The scheme was designed by Robert Bray Associates (RBA) and part-funded by the . Two groups were formed at the start of the pilot – one of residents and another of local council and external experts including Southern Water, The Aquifer Partnership, and the University of Brighton. The groups helped to inform the pilot design and development, up to and including the implementation stage.
The Carden pilot involved creating several shallow basins in existing grassed road verges along the avenue. These were planted with native wetland and wildflower grasses. The authority also dug swales (shallow ditches), among other new features. The new features work by collecting, cleaning and storing water until it can seep into the ground.
The Carden Avenue pilot was completed in spring 2022. The council worked in partnership with Southern Water to model whether significant rainfall events could be mitigated by the new SuDS measures. This analysis found that the scheme had the potential to temporarily store surface water runoff that could help reduce the risk of flooding locally.
Reports from residents affected by flooding in the past have been broadly positive. They saw the system working during rainy months, and the new infiltration basins filling with water. Residents previously affected by flooding saw a reduction in the anxiety and sleeplessness they had experienced during wet periods. In the spring, the area has also attracted visitors to pick wildflowers and spending time around the newly created green space.
In addition to these mental health, public realm and amenity benefits, the project is estimated to have saved £20,000 per property in flood damage.
Partnership and Collaboration
The design and implementation of the SCAPE project for Brighton & Hove involved collaboration between the council, technical experts, international partners and the local community. The EU support through the Interreg 2 Seas Programme was essential, providing much needed funding, expertise and overall technical knowledge to determine how to implement SuDS. International expertise was provided by project partners, in particular the City of Ostend (lead EU partner on the project) and Ghent University in Belgium. Ghent also developed a ‘Climate Test’ methodology to compare different flooding adaptation projects which were previously unable to be evaluated.
Learning in action and smart procurement
Because of the unique nature of SuDS design, the contractors needed good communication with Robert Bray Associates and the council’s flood risk team, as well as on-the-job learning and training. The contractors chosen regularly deliver roadworks for the council, so the project has improved SuDS-related skills and knowledge amongst Brighton & Hove based contractors ahead of potential future projects.
Strong engagement with the community
The council consulted communities throughout the project. At its start, consultation events were held in local venues for people to share feedback on the overall concept. The council considered community feedback, and alleviated concerns through design changes – for instance, sticking to a natural landscape and dropping play features due to safety concerns.
Throughout the project the council shared regular community newsletters and ran drop-in sessions to gather feedback on evolving proposals. Officers went door-to-door to deliver newsletters on foot. This was cheaper than posting them and gave officers a chance to talk to people face to face.
Breaking silos
A SuDS project has lots of moving parts. Having an in-house group where all the various council departments relevant to the project are represented made delivery smoother for Brighton & Hove. The collaborating teams included; City Planning, Flood Risk, Sustainability, Highways, City Parks, Property & Design, Housing Regeneration teams and more.
Funding
The Carden Avenue works cost around £237,000. The SuDS are maintained by the council’s Highways team, supported by the Parks and City Cleansing teams.
Expertise
The technical expertise and additional funding from the EU programme was vital. Support included soil testing and flow path analysis along with an in-depth understanding of SuDS technology. The council uses the knowledge gained through the SCAPE programme as it designs new SuDS projects.
Expect the unexpected, plan for redesign
The scheme was redesigned in response to residents’ fears that children would fall into, or play in, the new basins. This meant costs were higher than those in the initial budget.
If possible, avoid introducing SuDS in areas with underground services – such as utility pipes and cables. Realigning services can be particularly costly. Accommodating unmapped, undetected apparatus during construction can cause delays and require re-design. If it is not possible to avoid services, consider lower impact digging techniques, such as hand-digging or vacuum or suction excavation techniques.
Plan to care for SuDS during extreme heat and planting seasons
At the planting stage of the SuDS, a particularly dry period created concerns over the death of the system’s plants. During this period, the council asked residents to utilise their household water taps to water the SuDS plants. Engaging residents was therefore vital for ensuring the SuDS planting took hold.
The need to plant at the correct time during the planting season meant that construction work was completed earlier, with planting deferred for better weather conditions in spring.
Different levels of resident engagement
As with all council projects, some residents will be more enthusiastic whilst others will be more critical of the changes taking place. For SuDS and other flood interventions, works must take place further up the catchment to protect people and properties further downstream. This may result in a split in attitudes between those residents who are regularly flooded and those who are unaffected by flood risk but will be affected by construction works.
Initially, it was the former group of residents – those at risk – who attended early meetings with council officers. Then, as works progressed and became a reality, residents closer to the site began attending. Being able to balance the urgent needs of those at risk from flooding with the objections of those less affected is key; provide a listening ear, offer to minimise inconvenience where possible yet also set clear boundaries to keep making progress. Even residents who are less keen can be a valuable source of knowledge, able to describe or map out how weather patterns affect their local environment – for instance, one resident on Carden Avenue drew a map to show exactly where rainwater flowed down the street.
Keeping a record of your engagement activities can help address objections that residents were not consulted. Having evidence – photos and dates of contact – is useful to have on hand.
Local councillors as ambassadors
Getting supportive local councillors on board and informed about the development of a SuDS project can be invaluable when it comes to overcoming or mitigating resident concerns. For the Carden Avenue project, the local councillor was an advocate who was able to support officers by being a messenger and a vehicle for residents to air their concerns.
SuDS continue to be part of Brighton & Hove’s strategy to reduce flood risk and adapt communities to climate change. The knowledge and expertise gathered through the SCAPE project has enabled the acceleration of SuDS within the city.
Following on from its 2030 Carbon Neutral programme, in 2023 the council commissioned a climate risk and vulnerability assessment to better understand how climate change is affecting the city and to inform a strategic approach to climate adaptation.
The council’s Carbon Neutral Fund has supported projects creating carbon reduction, adaptation and conservation and enhancement of biodiversity. These include introducing tree pit drainage systems to reduce flood risk, and installing two raingardens in the city. The authority has also bought a decompaction machine. By injecting air underground in high use, mown grass areas, the device improves their water retention and carbon sequestration.
Action is being taken forward into changes in planning policies. For example, City Plan Policy DM43 requires the design and layout of all new buildings – and the development of car parking – to take a landscape-led approach from the outset and to incorporate drainage systems which have been sensitively located. The policy recognises the potential for SuDS to directly contribute to biodiversity and other improvements. The council’s Sustainable Drainage Supplementary Planning Document complements this policy and asks developers of 10 houses or more, over 1 hectare or more or buildings over 1,000m2 to submit a SuDS Management Plan.
The Aquifer Partnership, which assisted with the Carden Avenue pilot, is also delivering rainscapes in schools across the city. This includes one in Carden Primary School, opposite the Carden Avenue SuDS. The partnership is also delivering a flagship scheme in Wild Park, Brighton.
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