Urbanisation, population increase and the impact of climate change have exposed cities and towns to major risks of urban flooding and watercourse pollution, which are likely to become more frequent in the upcoming years. These not only have negative social and economic impacts, but also contribute to biodiversity loss. Severn Trent are addressing this critical issue in Mansfield by placing thousands of nature-based solutions across the whole town, known as sustainable drainage systems (SuDS) or blue green infrastructure.
Part of the Mansfield Sustainable Flood Resilience (MSFR) project, Arup was appointed to help Severn Trent design and implement an urban flood resilience scheme based on biodiversity interventions instead of traditional drainage systems. Turning the town into a sponge, these blue green interventions will free up capacity in sewers by capturing up to 58,000m3 of surface water.
Benefiting a local community of around 90,000 people, this scheme will improve flood resilience and local river water quality while enhancing the public realm and biodiversity by bringing new green spaces to the town.
58,000m³ of planned surface water capture
90,000 people benefit from improved flood risk
Designing the largest flood resilience scheme in the UK
Providing multidisciplinary services such as landscape architecture, water and civil engineering design and leveraging our digital skills, our teams worked closely with Severn Trent from planning through to delivery. As the largest sustainable drainage project in the country, the scheme demonstrates that designing nature-based flood resilience schemes at a town-scale is possible, and that this can also be done at pace. Accelerating the transition to a more resilient world, our digital innovation and technology expertise were key to make this happen.
We used Terrain, one of our digital tools, to identify Mansfield's neighbourhood structure and typologies, and our urban design expertise to quantify the most suitable interventions and their benefits. This was complemented by a bespoke digital application which allowed Severn Trent to create a strategy to deliver the scheme across the whole town. These data-driven tools have been essential to overcome the limits of traditional methods, which cannot assess large areas such as cities but only smaller spaces.
Tackling water challenges through nature
Instead of using traditional or grey interventions, thousands of different nature-based solutions such as rain gardens will be placed in different locations across the town. These will reduce the impact of extreme storm events by catching water runoff from roads and roofs, and slowing the flow of stormwater into the ground or existing sewers.
Increasing the water storage capacity of the town, the design will provide up to 60% of the additional water capacity needed by 2050. This will mitigate the need for traditional infrastructure such as buried tanks or new sewers, which are often made of concrete and therefore carbon intensive.
Delivering positive outcomes beyond flood resilience
Transforming streets across Mansfield, the scheme demonstrates how nature-based solutions can increase resilience against flooding and climate change whilst bringing additional environmental and social benefits.
The rain gardens, bioswales or basins will bring more greenery to the public spaces, improving the urban realm and creating more aesthetically pleasing places. These revitalised urban spaces will add to the vibrancy of the town, encouraging people to spend more time outdoors and bringing more opportunities to interact with others.
Improving public spaces and amenities will not only reinvigorate street life; it will also benefit the local community through access to better air and cleaner natural waters. New plants will reduce pollution and sequester carbon from the atmosphere whilst the soil will help filter any stormwater passing through it. The scheme will also bring economic benefits by providing new career opportunities and creating approximately 390 local jobs.
The growth in urban greening will not only benefit people but also wildlife. For example, the blue green interventions installed across the town will bring more diverse plants to the area, providing shelter and food for invertebrates, birds and animals. Sustainable flood resilience schemes like Mansfield demonstrate the potential for nature-based solutions to make towns and cities more resilient to climate change, whilst improving quality of life for residents and boosting biodiversity.