Real-time data is unlocking the performance of the UK’s largest retrofit SuDS project, offering lessons for utilities embracing nature-based solutions at scale.
Once highly vulnerable to flooding, the historic market town of Mansfield in Nottinghamshire is being transformed by the UK’s largest sustainable drainage system retrofit project, combining large-scale nature-based solutions with intelligent, real-time monitoring.
Led by Severn Trent Water, in collaboration with the University of Sheffield and the University of Liverpool, the £76 million Mansfield Sustainable Flood Resilience project demonstrates how digital monitoring can underpin the effective operation of complex blue-green infrastructure in dense urban environments.
Central to the project is Metasphere, a Grundfos company, whose Sense Level monitoring technology is providing the data backbone required to understand, manage and optimise the system.
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Building storage into the urban landscape
Commencing in spring 2022, the Mansfield project was designed to address increasing flood risk driven by more frequent and intense rainfall events. The scheme retrofits the existing urban catchment with approximately 20,000 individual SuDS features, spanning more than 15 hectares.
Once complete, the system will be capable of storing more than 58 million litres of surface water, significantly reducing flood risk for around 90,000 residents across a population of 109,000. The SuDS network includes tree pits, rain gardens, bioswales, detention basins and permeable paving, all designed to slow, store and infiltrate runoff while reducing pressure on the sewer network.
Angus Smith, Severn Trent’s lead project manager for the scheme, said the project set a new benchmark for urban flood management.
“The Mansfield SuDS project is a landmark initiative for Severn Trent, setting a new benchmark for how we integrate nature-based solutions into urban water management,” Smith said. “Metasphere’s intelligent monitoring technology has been absolutely critical to this, offering a clear understanding of how effectively rainwater runoff is being managed in real-time.”
Turning SuDS into measurable assets
Metasphere’s Sense Level technology, a compact, radar-based level sensor, was selected to monitor water levels across key SuDS components and selected points within the sewer network. The battery-powered units transmit continuous data via a mobile network to a cloud-based platform, giving operators and researchers a near real-time view of system behaviour.
This visibility enables accurate calculation of drainage volumes and supports detailed hydrological modelling, allowing the project team to understand how the system responds under different rainfall conditions. Importantly, it allows performance to be measured rather than assumed.
Dr Simon De-Ville, lecturer in water and environmental engineering at the University of Liverpool, said this level of data resolution was critical.
“Comprehensive data plays a critical role in optimising SuDS performance,” De-Ville said. “Understanding inflow, interaction within the system and outflow sounds simple, but the practicalities are complex, particularly in modified urban landscapes.”
To address data gaps, the project team deployed its own network of rain gauges and used continuous level monitoring to capture both extreme flows and low-flow ‘dribbles’, which are essential for validating hydraulic and hydrological models.
From research tool to operational insight
While the universities’ primary focus is long-term evaluation of SuDS performance, the availability of real-time data has delivered unexpected operational benefits. Continuous monitoring is now being viewed as an asset health tool, capable of identifying issues such as slow drainage or blockages before they escalate.
“This kind of monitoring enables proactive maintenance and extends the effective life of SuDS infrastructure,” De-Ville said. “It moves SuDS from being passive assets to actively managed systems.”
Challenges encountered during the project have also informed future deployment strategies. A prolonged mobile network outage highlighted the importance of resilience in communications infrastructure, while concerns about theft and vandalism in public spaces led Metasphere to redesign installations so sensors could be discreetly placed beneath access covers within sewer infrastructure.
Implications for the water sector
As the UK water industry enters the 2025–30 AMP8 cycle, the Mansfield project offers a timely demonstration of how nature-based solutions can be scaled, monitored and managed with confidence. Detailed performance data not only supports flood resilience outcomes but also strengthens the business case for wider adoption by validating design assumptions and informing future standards.
The project also signals Metasphere’s entry into the SuDS sector, positioning intelligent monitoring as a critical enabler of large-scale blue-green infrastructure.
Replicated nationally, similar schemes could play a significant role in reducing flood risk, lowering combined sewer overflow activations and delivering wider biodiversity and amenity benefits. In Mansfield, the combination of SuDS and real-time monitoring is already reshaping how urban flood resilience is planned, delivered and understood.