Blue-Green Cities Research Project (2013-2016)

Blue-Green Cities Research Project (2013-2016)

Thorne led the Blue-Green Cities research project (2013-2016), funded by the Engineering and Physical Sciences Research Council (EPSRC), that aimed to deliver and evaluate the multiple flood risk benefits in Blue-Green Cities. Led by Thorne, the Research Consortium included 8 UK universities: the University of Nottingham, the University of Leeds, the University of Cambridge, Heriot-Watt University, Newcastle University, the University of the West of England, Cranfield University and the London School of Economics as well as partners in the US and China. In June 2013 the Research Consortium selected Newcastle upon Tyne as a Demonstration City partly in response to the June 'Toon Monsoon' in 2012. A Blue-Green City aims to reconfigure the urban water cycle to resemble a naturally-oriented water cycle while contributing to the amenity of the city by bringing water management and green infrastructure together. This is achieved by combining and protecting the hydrological and ecological values of the urban landscape while providing resilient and adaptive measures to address future changes in climate, land use, water management, and socio-economic activity in the city. A Blue-Green City is more than the blue and green infrastructure that it comprises; it is a holistic concept that requires collaboration between government, industry and public stakeholders and partnerships working to be fully implemented. Blue-Green Cities generate a multitude of environmental, ecological, socio-cultural and economic benefits through integrated planning and management and may be key to future resilience and sustainability of urban environments and processes. In addition to making the urban environment more resilient to flood and drought events, a Blue-Green City is designed to maximise the use of water as a resource, e.g. through rainwater harvesting, irrigation of river channels, groundwater recharge and as a local amenity. Water is preferentially attenuated and stored on the surface to maximise the potential environmental and social benefits, and reduce stress on the subsurface piped sewer system. A Blue-Green City also aims to collect and store water during flood events for later use in times of drought. Background on the StudyBlue-Green Cities aim to reintroduce the natural water cycle into urban environments and provide effective measures to manage fluvial (river), coastal, and pluvial (urban runoff or surface water) flooding while championing the concept of multi-functional green space and land use to generate multiple benefits for the environment, society, and the economy. Visible water in cities has massively declined in the last century and many areas are facing future water scarcity in response to changes in climate, land use and population. The concept of Blue-Green Cities involves working with green and blue infrastructure components to secure a sustainable future and generate multiple benefits for the environmental, ecological, social and cultural spheres. This requires a coordinated approach to water resource and green space management from institutional organisations, industry, academia and local communities and neighbourhoods. The natural water cycle is characterised by high evaporation, a high rate of infiltration, and low surface runoff. This typically occurs in rural areas with abundant permeable surfaces (soils, green space), trees and vegetation, and natural meandering water courses. In contrast, in most urban environments there is more surface runoff, less infiltration and less evaporation. Green and blue spaces are often disconnected. Meaning for a city to be Blue-Green, it requires a further step beyond the implementation of blue and green infrastructure. The lack of infiltration in urban environments may reduce the amount of groundwater, which can have significant implications in some cities that experience drought. In urban environments water is quickly transported over the impermeable concrete, spending little time on the surface before being redirected underground into a network of pipes and sewers. However, these conventional systems ('grey' infrastructure) may not be sustainable, particularly in light of potential future climate change. They may be highly expensive and lack many of the multiple benefits associated with Blue-Green infrastructure. Land planning and engineering design approaches in Blue-Green Cities aim to be cost effective, resilient, adaptable, and help mitigate against future climate change, while minimising environmental degradation and improving aesthetic and recreational appeal. Key functions in Blue-Green Cities include protecting natural systems and restoring natural drainage channels, mimicking pre-development hydrology, reducing imperviousness, and increasing infiltration, surface storage and the use of water retentive plants. A key factor is interlinking the blue and green assets to create Blue-Green corridors through the urban environment. Blue-Green Cities favour the holistic approach and aim for interdisciplinary cooperation in water management, urban design, and landscape planning. Community understanding, interaction and involvement in the evolution of Blue- Green design are actively promoted(e.g. Newcastle's LAA). Blue-Green Cities typically incorporate sustainable urban drainage systems (SUDS), a term used in the United Kingdom, known as water-sensitive urban design (WSUD) in Australia, and low impact development or best management practice (BMP) in the United States. Green infrastructure is also a term that is used to define many of the infrastructure components for flood risk management in Blue-Green Cities. Water management components in Blue-Green Cities are part of a wider complex "system of systems" providing vital services for urban communities. The urban water system interacts with other essential infrastructure such as information and telecommunications, energy, transport, health and emergency services. Blue-Green Cities aim to minimise the negative impacts on these systems during times of extreme flood while maximising the positive interactions when the system is in the non-flood state. Key barriers to effective implementation of Blue-Green infrastructure can arise if planning processes and wider urban system design and urban renewal programmes are not fully integrated. Components of a Blue-Green CityA Blue-Green City actively works with existing grey infrastructure to provide optimal management of the urban water system during a range of flood events; from no flood, to minimal flooding, to extreme rainfall events where the drainage system may be exceeded. Due to these holistic and practical ideals, many infrastructure components and common practices may be employed when planning and developing a Blue-Green City, in line with specific local objectives, e.g. water management, delivery of multi-functional green infrastructure, biodiversity action plans. The key functions of Blue-Green infrastructure components include water use/reuse, water treatment, detention and infiltration, conveyance, evapotranspiration, local amenity provision, and generation of a range of viable habitats for local ecosystems. In most cases, the components are multi-functional. Blue-Green infrastructure includes: Bioretention systems Bioretention swales Swales and buffer strips Storage ponds, lakes and reservoirs Controlled storage areas, e.g. car parks, recreational areas, minor roads, playing fields, parkland and hard standing in school playgrounds and industrial areas Green roofs Sand filters and infiltration trenches Permeable paving Rain gardens Stream and river restoration De-canalisation of river corridors and re-introduction of meanders Constructed wetlands Property level strategies to reduce surface water and manage runoff, such as water butts (or rainwater tanks in the US), Open green space Parks and gardens Street trees Pocket parks Vegetated ephemeral waterways Planted drainageBenefits of a Blue-Green cityA Blue-Green City contains an interconnected network of blue and green infrastructure that work in harmony to generate a range of benefits when the system is in both the flood state and non-flood state. As a concept, Blue-Green Cities accept the need for grey infrastructure in certain scenarios to maximise the benefits accrued.. A wide range of environmental, ecological, economic and socio-cultural benefits are directly and indirectly attributed to Blue-Green Cities. Many benefits are realised during times of no flood (green benefits), giving Blue-Green Cities a competitive edge over otherwise comparable, conventional cities. Multi-functional infrastructure is a key to generating the maximum benefits when the system is in the non-flood state. An ecosystem services approach is frequently used to determine the benefits people obtain from the environment and ecosystems. Many of the good and services provided by Blue-Green Cities have economic value, e.g. the production of clean air, water and carbon sequestration. The benefits include; Climate change adaptation and mitigation Reduction of the urban heat island effect Better management of stormwater and water supply, conservation of water resources through efficiency (increasing the resilience to drought) Carbon reduction/mitigation Improved air quality Increased biodiversity (including the reintroduction and propagation of native species) Habitat and biodiversity enhancement Water pollution control Public amenity (recreational water use, parks and recreation grounds, leisure) Cultural services (physical and mental health, well-being of citizens, aesthetics, spiritual) Community engagement Education Landscaping and quality of place Increased land and property values Labour productivity (stress reduction, attracting and retaining staff) Economic growth and investment Food production Healthy soils and a reduction in soil erosion and river bank retreat Tourism Reduction in the accumulation of sediment, debris and pollutants in Urban watercourses Shading and shelter around rivers and the wider urban environment Economic benefits related to avoided costs from flooding Community cohesion and greater understanding of sustainable planning and lifestyle Possible diversification of the local economy and job creation Strengthening ecosystem resilience Ecological corridors and landscape permeability (biodiversity benefits) Avoided impacts of flood events, including avoided damage to the economy, wildlife, buildings and infrastructure, and avoided trauma and distress (mental health impacts) associated with flooding The multiple benefits of adopting Blue-Green infrastructure will span both the local/regional and global/international scales. The Department of Environment, Farming and Rural Affairs' (DEFRA) approach to flood and coastal risk management has been to seek multi-functional benefits from Flood and Coastal Erosion Risk Management (FCERM) interventions and enhance the clarity of social and environmental consequences in the decision making process. DEFRA note, however, that flood risk reduction benefits provided by ecosystems are not well understood and this is an area where more systematic research is needed such as the SWITCH project.