Blue-greening cities for climate change adaptation

The risk of flooding is becoming ever more serious, both in the UK and across the globe, and the challenge of protecting our homes and cities is becoming increasingly important.

Cities around the world face the challenge of adapting to the impacts of climate change. In the UK, we are experiencing warmer and wetter weather, and scientists predict that intense rainfall and extreme storm events will become more frequent over the coming decades. Urbanisation and reductions in urban green space further increase flood risk and remove valuable connections with nature.

A different approach to managing urban flood risk is needed to make our cities more resilient to climate change impacts. Traditionally, defensive walls, barriers and underground pipes (grey infrastructure) were used to defend cities, moving water away from the surface as quickly as possible. Water was regarded as a ‘nuisance’. Instead, we need to view water as a vital resource, and work with nature to recreate more natural water cycles in cities.

Blue-green infrastructure offers a resilient approach to urban flood and water management. Blue-green features such as swales (vegetated channels), wetlands, rain gardens and green roofs are designed to mimic and/or enhance natural processes. One of the big advantages over grey infrastructure are the additional co-benefits that Blue-Green infrastructure can deliver. This includes increasing wildlife and biodiversity, improving water quality, enhancing mental and physical health through improved recreational opportunities and access to nature, and bringing economic opportunities. In short, increasing our quality of life in cities.

Blue-Green infrastructure can reduce vulnerability to other climate change risks, including heat stress, air pollution and drought. This aligns with the Sustainable Development Goals (SDG) around good health and well-being (SDG3), clean water and sanitation (SDG6), and sustainable cities and communities (SDG11). Key to achieving these benefits is to design Blue-Green infrastructure to be multifunctional – to deliver multiple co-benefits that address a range of societal and environmental challenges. In urban areas, where space is at a premium, we need to rethink how we use our existing spaces, for example, adding a green roof to buildings, or greening tram tracks.

We also know that this approach can work – fantastic examples of multifunctional Blue-Green infrastructure can already be found internationally, providing us with opportunities to learn from best practice. A recent study led by Professor Simon Gosling (School of Geography) and I explored international perceptions of urban Blue-Green infrastructure across four cities (Newcastle – UK, Rotterdam – Netherlands, Portland – Oregon, USA, and Ningbo – China), finding that Blue-Green infrastructure is universally valued for its positive impact on residents’ quality of life. In the UK, there is much to learn from Ningbo’s Sponge City programme, Rotterdam’s climate change adaptation plans, and Portland’s green storm water management initiatives.

" Collaboration and co-development are key to building a strong Blue-Green vision. "
Dr Emily O'Donnell

Delivering multifunctional Blue-Green infrastructure is difficult and requires acceptance and support from multiple stakeholders and the community. Collaboration and co-development are therefore key to building a strong Blue-Green vision.

I have worked with stakeholders in Newcastle and Nottingham to explore how we might get the most out of our Blue-Green infrastructure. For example, I coordinated the Newcastle Learning and Action Alliance during the Blue-Green Cities and Urban Flood Resilience research projects, which successfully facilitated collaboration between public and private organisations within the city and a co-created Blue-Green vision. Our Newcastle Blue and Green Declaration was signed by several key stakeholders, including the City Council and the Environment Agency. Members of the Newcastle Learning and Action Alliance have effectively used whole-group learning to influence policy and practice towards multifunctional Blue-Green infrastructure, building on the work that I started when I coordinated the Alliance.

Blue-Green infrastructure should be a prominent part of discussions at COP27 Water Day due to its ability to tackle a range of climate adaptation challenges. Engagement with stakeholders and communities is key to highlighting the value of multifunctional Blue-Green infrastructure and delivering joined up projects that really do make our cities better places to live.