English academic
Colin Reginald Thorne (born September 1952) is Chair of Physical Geography at the University of Nottingham. A fluvial geomorphologist with an educational background in environmental sciences, civil engineering and physical geography; he has published 9 books and over 120 journal papers and book chapters.
He was educated at Kelvin Hall School and the University of East Anglia (BSc; PhD, 1978). He was awarded the Collingwood Prize by The American Society of Civil Engineers in 1986 and the Back Award of the Royal Geographical Society in 2016.
Colin has been heavily involved in governmental policy including leading the geomorphology work package in the UK's Foresight flood and coastal defence project. He has also sat on the government's SAGE advisory group after the UK Floods. Professor Colin Thorne's research has also had public impact in the Costa Rica vs. Nicaragua International Court of Justice case, where Colin acted as an expert witness.
During a career spanning four decades, has held academic posts at UEA, Colorado State University, the USDA National Sedimentation Laboratory, USACE Waterways Experiment Station, NOAA Fisheries, and the University of Nottingham. He is also a Concurrent Professor at Nanjing University and an Affiliate Professor at Colorado State University.
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 study.
Blue-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 City.
A 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:
Benefits of a Blue-Green city.
A 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;
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.
Work Package 4 of the Blue Green Cities Project involved the creation of a multiple benefit analysis GIS tool box which complements BeST SuDS management tools. The package normalises different Blue-Green benefits so that different scales of benefit can be analysed together thus allowing a quantification of all the potential benefits of new infrastructure.
Blue-Green cities case studies.
Concepts of water sensitive cities, such as Blue-Green cities, and tools for water-centric urban design are developing in many countries. For developed cities this may be a case of small changes and building back better with progressive redevelopment. For developing cities the process may be much quicker and circumvent the outdated sewage systems in older cities. Few, if any UK cities have progressed beyond “the drained city“ stage, with water managed for a series of single functions (including flood risk management), mostly through distribution, collection and treatment systems and drainage infrastructure that are energy intensive and which continue to degrade urban environments in general and urban watercourses, in particular. International case studies and the Newcastle demonstration city show the potential of blue green cities in a variety of contexts. The research consortium led by Colin intends to lead a shift in urban developments to reach the potential shown in these case studies.
Newcastle upon Tyne Demonstration City.
Newcastle was chosen as a demonstration city for the Blue-Green cities Project due to links with Newcastle University and its Estates, the 2012 flood events and the vulnerability of the city centre to further flash floods. A high percentage of the city centre is impermeable and often unable to cope with high volumes of rain over short periods. A combination of the surface water management plan and community led Learning and Action Alliance was used to select detailed areas to study. These were the middle Ouseburn, Newcastle Great Park and the urban core and adjoining residential area of Wingrove.
SuDS were shown to positively reduce flooding in the Newcastle Great park housing estate and the CityCat flood simulations can be viewed. SuDS were also shown to retain as much as 54% of the suspended sediment that is transported into the ponds, instead of pushing it downstream into the Ouseburn. On top of the ecosystem services benefit to carbon sequestration and habitat size, and reduce air pollution, noise and flood risk the Blue-Green city concept was shown to have successfully created resident approval. 90% of residents’ surveyed (299 total responses) like the SuDS ponds and 61% understand the role of the ponds in reducing flood risk.
Multi-benefit analysis was carried out for Wingrove and Newcastle's urban core using the Multiple benefit tool box created by the research consortium. Evaluation showed that potentially Blue-Green infrastructure in Wingrove would reduce noise and air pollution, increase carbon sequestration and habitat size, and improve access to greenspace for residents. This increase in green space could create a network of blue-green space throughout the city. Showing that despite the impressive improvements already made, there are further potential gains from implementing the Blue-Green city concept in Newcastle.
Portland, USA.
The Consortium studied the development of the city Portland, to question whether it fit the Blue-Green city concept. It was decided that Portland has advanced into a world-leading Blue Green city through the ‘Grey to Green’ initiative at the turn of the century. This led to a sustainable storm water plan which incorporated Green roofs, tree planting and Green streets. Monitoring reports commissioned suggest that eco-roofs have halved discharge into sewage/stormwater drains. This project was combined with new grey