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The blue-green path to urban flood resilience
Emily O’Donnella,*, Colin Thornea, Sangaralingam Ahilanb, Scott Arthurc,
b, David Dawsone, Glyn Everettf,
Stephen Birkinshawd, David Butler
Richard Fennerg, Vassilis Glenisd, Leon Kapetasg, Chris Kilsbyd, Vladimir Krivtsovc,
Jessica Lamondf, Shaun Maskreya,h, Greg O’Donnelld, Karen Potteri, Kim Vercruyssee,
Tudorel Vilcani and Nigel Wrightj
a
School of Geography, University of Nottingham, Nottingham NG7 2RD, UK
b
Centre for Water Systems, College of Engineering, Mathematics and Physical Sciences, University of Exeter,
Exeter EX4 4QF, UK
c
School of Energy, Geoscience, Infrastructure and Society, Heriot-Watt University, Edinburgh EH14 4AS, UK
d
School of Engineering, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
e
School of Civil Engineering, University of Leeds, Leeds LS2 9JT, UK
f
Centre for Architecture and Built Environment Research (CABER), University of the West of England, Bristol BS16 1QY, UK
g
Centre for Sustainable Development, Engineering Department, Cambridge University, Cambridge CB2 1PZ, UK
h
Environment Agency, King’s Meadow House, Reading RG1 8DQ, UK
i
Department for Public Leadership and Social Enterprise, The Open University Business School, The Open University,
Milton Keynes MK7 6AA, UK
j
Nottingham Trent University, Nottingham NG1 4FQ, UK
*Corresponding author. E-mail: emily.o’donnell@nottingham.ac.uk
Abstract
Achieving urban flood resilience at local, regional and national levels requires a transformative change in
planning, design and implementation of urban water systems. Flood risk, wastewater and stormwater management should be re-envisaged and transformed to: ensure satisfactory service delivery under flood, normal and
drought conditions, and enhance and extend the useful lives of ageing grey assets by supplementing them
with multi-functional Blue-Green infrastructure. The aim of the multidisciplinary Urban Flood Resilience (UFR)
research project, which launched in 2016 and comprises academics from nine UK institutions, is to investigate
how transformative change may be possible through a whole systems approach. UFR research outputs to
date are summarised under three themes. Theme 1 investigates how Blue-Green and Grey (BG þ G) systems
can be co-optimised to offer maximum flood risk reduction, continuous service delivery and multiple co-benefits.
Theme 2 investigates the resource capacity of urban stormwater and evaluates the potential for interoperability.
Theme 3 focuses on the interfaces between planners, developers, engineers and beneficiary communities and
investigates citizens’ interactions with BG þ G infrastructure. Focussing on retrofit and new build case studies,
UFR research demonstrates how urban flood resilience may be achieved through changes in planning practice
and policy to enable widespread uptake of BG þ G infrastructure.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC BY 4.0), which permits copying,
adaptation and redistribution, provided the original work is properly cited (http://creativecommons.org/licenses/by/4.0/).
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Key words: Blue-Green Cities, Blue-Green infrastructure, flood risk management, interoperability, sustainable
drainage systems, urban flood resilience
INTRODUCTION
There is a recognised need for a transformative change in how urban environments manage water in
response to more frequent and extreme storm events, drier summers and increasing urbanisation that
reduces permeable greenspace and moves cities further away from natural water cycle processes. More
than 50% of the world’s population currently reside in cities, which is expected to rise to 68% by 2050
(UN 2018), resulting in stress on already overburdened drainage infrastructure and elevated flood risk
to people, property and critical infrastructure systems, e.g. transport, communications and energy. In
the UK, annual expected damage due to flooding exceeds £1 billion (Environment Agency 2014). The
economic losses of flooding go far beyond direct damages; frequently the consequential business disruption, supply chain shocks and welfare effects (e.g. health and wellbeing impacts) equal or exceed direct
damage (Hallegatte 2008), in addition to costs associated with degradation of ecosystem services.
In response to these trends and predictions, global cities are rethinking their approaches to flood
risk management. Alongside continuing investment in traditional grey infrastructure (e.g. flood
walls, barriers, lined drainage channels, underground pipes and detention tanks), many cities are
transitioning from solely flood defence to greater water resilience by implementing approaches
centred on, for example, water sensitive urban design (Sharma et al. 2016), sustainable drainage systems (SuDS) (Lashford et al. 2019), green infrastructure (Trogrlić et al. 2018) and ‘Sponge Cities’
(Zevenbergen et al. 2018). These approaches are subtly different but all embody the concept of a
‘Blue-Green City’, where integrated water management and green infrastructure work in concert to
recreate a naturally oriented water cycle to help manage flood risk while delivering multiple benefits
to the environment, society and economy (Lawson et al. 2014).
In 2015 the UK House of Commons Commission of Inquiry into flood resilience highlighted a
change in mindset from protection towards resilience, proposing ‘living with and making space for
water and the opportunity to get “more from less” by seeing all forms of water as providing multiple
benefits’ (House of Commons 2015). The intense, prolonged rainfall and catastrophic flooding in
December 2015, which followed the winter 2013–14 floods, provided an unwelcome but powerful
endorsement of the need for greater urban flood resilience.
We define urban flood resilience as a city’s capacity to maintain future flood risk at tolerable levels
by preventing death and injuries, minimising damage and disruption during floods, and recovering
quickly afterwards, while managing water quality and ecosystems, and ensuring social equity, and
economic, environmental and cultural vitality. The multidisciplinary Urban Flood Resilience (UFR)
research project was launched in October 2016 to conduct the research necessary to understand
how UK urban flood resilience may be achieved at local, regional and national levels. The UFR project, scheduled to finish in May 2020, investigates how such transformative change may be possible
using a Blue-Green and Grey (BG þ G) whole systems approach to urban flood and water management. The project is funded by the Engineering and Physical Sciences Research Council (EPSRC)
and comprises academics from nine UK institutions with expertise in hydrology, hydraulics, water
engineering, urban drainage, planning and governance, flood risk management, ecology, sediment
transport, stakeholder and community engagement, citizen behaviours, infrastructure resilience and
interoperability. Research builds on the earlier Blue-Green Cities research project (2013–2016) that
developed new strategies for managing urban flood risk as part of wider, integrated urban planning
intended to achieve environmental enhancement and urban renewal in which the multiple benefits
of Blue-Green Cities are rigorously evaluated and understood (Fenner 2017).
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With a focus predominantly on pluvial flooding, the objectives of the UFR Consortium are to
re-envisage and transform flood risk and stormwater management to develop strategies that ensure
satisfactory service delivery under flood, normal and drought conditions, and enhance and extend
the useful lives of ageing grey assets by supplementing them with multi-functional Blue-Green infrastructure (BGI). This includes swales, rain gardens, green roofs, wetlands, restored urban streams,
and other SuDS that actively use BGI to attenuate, store and infiltrate surface water. This paper introduces UFR research under three themes: (1) engineering design to enhance service delivery, (2)
optimum resource use across the flood-drought spectrum, and (3) flood risk management at the
heart of urban planning and delivery. Research is presented under five sub-themes that cover resilience under change, stormwater as a resource, interoperability, citizens’ interactions with BGI and
achieving urban flood resilience in practice (Figure 1). The key research findings (to date) are summarised and future deliverables from current research are outlined. We reference several publications
that have resulted from the UFR project (Costa et al. 2019; Fenner et al. 2019; Krivtsov et al. 2019;
Vercruysse et al. 2019) where more detailed methodology and in-depth discussion are presented.
We begin by outlining the overarching methods and scope.
Figure 1 | Urban Flood Resilience research project structure. The Work Packages (WP) are shaded according to research
theme. BG þ G, Blue-Green and Grey.
METHODS AND SCOPE
Locally defined methods and models are tested in several UK case studies (including Newcastle,
Ebbsfleet, Edinburgh and Carshalton, London) and spatially linked through the ‘stormwater’ cascade
(Figure 2), enabling transferability and up-scaling to regional and national levels. The engineering
core of the project couples an array of physics-based models to support investigations of how stormwater travels through a city’s drainage system, accounting for the dynamics of water, sediment,
debris and contaminants carried by urban runoff. Simulations of water flow and storage are used to
investigate how the performance of grey systems can be improved by adding BGI to create integrated
treatment trains designed to manage both the quantity and quality of urban runoff. Models and
design solutions are being developed and tested in the contexts of retro-fit (e.g. as part of urban renewal
and uplift in Newcastle) and new build (e.g. as part of the creation of a ‘Garden City’ in Ebbsfleet, Kent), to
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Figure 2 | The Urban Flood Resilience research project scope, covering the entire ‘stormwater cascade’ from when water
enters to when it leaves the urban area, employing a suite of linked research methods and models to simulate physical processes, and cross-tabulating with water governance, planning, and stakeholder attitudes, preferences and actions.
demonstrate how resilience to floods and droughts can be achieved using integrated systems of BG þ G
assets, under a range of future climates, to assure continuous, long-term service delivery. Adopting a whole
systems perspective is necessary to recognise interdependencies between the urban water system and other
systems, including transport and energy. This highlights potential opportunities for managing stormwater as
a resource, including non-potable uses in homes or commercial buildings via rainwater harvesting (RWH),
irrigating green infrastructure, groundwater recharge and micro-hydropower.
The path to UFR is also dependent on understanding citizen and community preferences with
respect to managing flood risk, and incorporating these into future system designs and upgrades.
Participatory Action Research and Social Practice Theory are used to examine the attitudes and
responses of citizens, communities and practitioners to innovation in flood and water management.
The engineering core of this project is thus underpinned by research into planning, urban development, and the collaborative governance of urban flood risk management, to identify mechanisms
whereby the engineering solutions identified above may be incorporated into practice and policy to
enable transformative change in urban flood risk management applicable to many countries and
regions. Engagement with planners, developers, land-owners, and engineers (local government,
private sector and non-governmental organisations (NGOs)) through Learning and Action Alliances
in Newcastle and Ebbsfleet explore responses to the innovative changes needed to achieve UFR and
helps ensure that research outputs meet the need of local practitioners (O’Donnell et al. 2018).
THEME 1: ENGINEERING DESIGN TO ENHANCE SERVICE DELIVERY (WP1)
Theme 1 investigates how integrated BG þ G treatment trains may be engineered to support resilient
management of water quantity and quality. Evaluating how multifunctional BG þ G systems can be
co-optimised to offer maximum flood risk reduction, while delivering multiple co-benefits, under a
range of future scenarios that account for climate and socio-economic change, is a key objective.
Urban drainage infrastructure has previously been developed to meet expected levels of service
performance criteria assuming stable conditions. In many cases, the buried pipework is reaching
the limits of its capacity and systems must be retrofitted to respond to new pressures including
extreme storm events that are exacerbated by climate change and rapid urban densification. The
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uncertainty associated with these drivers results in potentially costly solutions that are overdesigned
or inadequate system extensions that fail to provide the necessary additional capacity. This highlights
a need for flexible/adaptive designs that allow incremental investment in infrastructure to meet
performance requirements while maintaining cost-effectiveness (Buurman & Babovic 2016). WP1
has developed methodology and guidance on assessing a range of flexible adaptation pathways
as part of long-term planning and infrastructure design, to address the question: what is the most
effective mix of BG þ G systems in any given location at any time? The method has been tested in
Carshalton (London Borough of Sutton), exploring and prioritising a series of potential pathways
and developing a roadmap for adaptation over the next 40 years (Figure 3). This combines hydrodynamic modelling to identify when service thresholds are exceeded and trigger further intervention, and
evaluation (monetised and spatial incorporating a real options approach) of the multiple benefits of
different BG þ G pathways (Gersonius et al. 2015; Manocha & Babovic 2017; Fenner et al. 2019).
Additional criteria beyond a standard cost benefit analysis (CBA) form part of the decision-making
process. For instance, although grey pipe expansion scores ‘medium’ in the CBA it offers no adaptiveness as it is a one-off large scale intervention, nor does it offer any environmental or social benefits
(Figure 3). The adaptive pathways approach provides a pragmatic response to managing the uncertainties inherent in climate change and urbanisation over a variable planning horizon and can be
used to identify the most suitable mix of drainage infrastructure assets.
Figure 3 | Adaptation pathways tree and multi-criteria pathway assessment as a response to different rates of urbanisation.
Tipping points are identified when the (future) system reaches a capacity threshold due to urban densification pressure, as
expressed by an increasing % imperviousness of the urban catchment. A fast or slower rate of densification suggest that the
next step should be taken sooner or later, respectively. CBA, cost benefit analysis.
Hydrodynamic modelling of BG þ G systems has also been advanced through the development of a
new comprehensive model that bridges the interfaces between urban/rural and engineered/natural
hydrosystems by simulating water flow on the surface, in sub-surface pipe networks, and in the soil
and groundwater systems. Several previous studies have coupled hydraulic and hydrologic models,
e.g. semi-lumped hydrologic models providing the lateral and tributary flows to a hydraulic model
of the main channel reach (Lian et al. 2007; Nguyen et al. 2016). The impacts of urbanisation on
groundwater recharge using physically based hydrologic models coupled to urban stormwater
models have also been examined (Locatelli et al. 2017). Our focus is on runoff generation within
urban conurbations, which comprise a mosaic of impervious and green spaces. Hydrodynamic
models typically simulate runoff dynamics in urban areas over the duration of a storm event,
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neglecting the long-term hydrological processes in green spaces and the specification of antecedent
conditions. To overcome this limitation, the physically based SHETRAN hydrological model (Ewen
et al. 2000) has been coupled with the CityCAT hydrodynamic model (Glenis et al. 2018). SHETRAN
simulates a continuous representation of runoff, evapotranspiration, soil moisture and groundwater
storage to provide the antecedent conditions for CityCAT. This allows improved representation of
the impacts of land use and management on urban flood hydrology.
The physical basis and high spatial resolution of the coupled hydrosystems model provides a basis for
simulating the effects of land-use change, SuDS and BGI implementation, and climate change on runoff
and water storage, demonstrating a pivotal advancement in hydrosystems modelling. Interpretation of
model simulations has led to the following three key recommendations for future hydrosystems modelling:
1. It is necessary to differentiate between combined and separate sewer systems to accurately model
flows in urbanised water courses. This is illustrated by the increase in peak flow and reduction in
lag time when the Kingston Park surface water sewer discharges runoff into the Ouseburn, evident
by the rapid increase in discharge at the Three Mile depth gauge (Figure 4).
2. Accurate representations of effective impermeable and green areas (including gardens) requires high
resolution data; vector data is often preferable as detailed attribute information can be assigned to
individual features, with the OS Mastermap (UK Ordnance Survey) dataset used here.
Figure 4 | (a) and (b) Photographs of two SuDS ponds along a section of the Ouseburn, Newcastle, modelled in the CityCAT
simulation (source: Emily O’Donnell, June 2013 and February 2015, respectively). (c) CityCAT simulation showing water depth
and inundated SuDS features along the Ouseburn. The SuDS ponds are represented by the dark blue circles within the red box.
(d) Discharge hydrographs illustrating how the separate sewers from Kingston Park increase peak flow and decrease lag time,
illustrated by the rapid increase in discharge at the Three Mile (suburban) depth gauge.
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3. The problem of specifying the initial antecedent conditions in green spaces in an event-based
hydraulic model can be overcome through the coupling with a hydrologic model that explicitly
accounts for the role of seasonal variations in evaporation.
Achieving satisfactory levels of service in urban water systems is subject to a range of challenges
including increasing urban water demands due to population growth, increased flood risk due to
urbanisation and climate change, expectations of good water quality, ageing infrastructure and
issues associated with potential grey infrastructure retrofit, including negative environmental and
social impacts, and high energy demands. Evaluating new interventions in urban water systems
requires an integrated framework to measure system performance and interactive pathways, and
assess the sustainability of proposed schemes. WaterMet2, a conceptual simulation-type, massbalance-based model which quantifies metabolism related performance of integrated urban water
systems (Behzadian & Kapelan 2015) is being used to evaluate the sustainability performance and
quantify resource flows in the Ebbsfleet Garden City for three major urban water subsystems
(water supply, stormwater and wastewater). Outputs from the CityCAT hydrodynamic model (surface
and subsurface flows) feed into the stormwater and wastewater modules in the WaterMet2 model,
along with the water supply system characteristics, to evaluate overall urban water systems performance. A sustainability assessment of the existing urban water system is being undertaken (as business
as usual) and different strategic future interventions are assessed over a long-term planning horizon
that aligns with priorities of the Ebbsfleet Development Corporation and local water companies.
Sustainable urban water management options, e.g. RWH, greywater reuse and wastewater reuse,
are incorporated into the model, and different wastewater treatment options are evaluated, including
centralised and decentralised strategies. Performance of the urban water system is assessed through
social, environmental, economic and asset key performance indicators over the planning horizon.
Metabolism-based modelling is an advancement of current approaches as issues commonly encountered by independent modelling of urban water system components are overcome by considering the
interconnection and interdependencies of the urban water sub-systems.
THEME 2: OPTIMUM RESOURCE USE ACROSS THE FLOOD-DROUGHT SPECTRUM (WP2 AND WP3)
Stormwater is often considered a hazard with a focus on extreme events, yet the need to retain and
utilise stormwater as a vital resource is paramount as we enter a more uncertain climate. Theme 2
investigates how engineered stormwater management systems can be better aligned with natural
processes and other physical infrastructure to: (1) realise the resource potential of urban water,
with opportunities for storage, recovery and reuse identified at every stage of the urban water cycle
(WP2); and (2) improve integration of urban flood risk management and water, energy and transport
infrastructure through interoperability of urban systems-of-systems (WP3).
Managing stormwater as a resource
A range of stormwater reuse options are listed in Figure 5. We briefly discuss three options, focussing
first on the potential for micro-hydropower generation from the controlled release of water from
SuDS ponds. A novel screening tool to assess the feasibility of such energy recovery based on physical
site, climate and economic parameters has been developed (see Costa et al. 2019). This approach
focuses on how a retention pond may decouple the problem of intermittent rainfall and continuous
energy generation, and provides key insight into preferred characteristics for viable sites, e.g. significant head being favoured over a large flow as this permits smaller pipes and turbines which reduce
overall costs. The application of the tool to two case studies (Herefordshire, UK and Oregon City,
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Figure 5 | Options for direct and indirect stormwater reuse over the short and long term. BGI, Blue-Green infrastructure.
USA) highlights several critical dependent factors that influence the potential energy recovery from
stormwater discharge, notably abundant rainfall with a relatively even annual distribution, a large
contributing catchment and steep slopes. However, the requirements for optimal energy recovery
and to create effective SuDS schemes are likely to differ; SuDS on sloping ground with a large
difference in head are rare. This suggests that micro-hydropower recovery from SuDS that generates
enough revenue to justify the investment is highly dependent on unique site characteristics and there
may be limited opportunities in the UK.
The potential benefits of RWH on water supply augmentation and urban flood risk management
highlights an alternative approach with regards to stormwater as a resource. Nonetheless, the
global implementation of convention RWH systems varies greatly and systems often do not maximise
the potential benefits (Campisano et al. 2017). The UFR Consortium are evaluating the evolution of
RWH to Rainwater Management Systems (RMS), which represents a step-change whereby multifunctional systems can increase urban water resilience and sustainability by concurrently reducing water
demand, stormwater discharge and energy usage (embodied and operational). The performance of a
residential RMS in Newcastle based on a three-bedroom house with an 80 m2 roof area was evaluated
using 2012 rainfall data and the Rainwet model (Fewkes & Butler 2000) that calculates a daily
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supply-demand balance of rainfall, water demand and overflow discharges based on ‘yield after spillage’. A control simulation without RMS (Figure 6(a)) was compared to a passive RMS (Figure 6(b))
and an active RMS (Figure 6(c)), based on a 3,000 L storage tank. Active RMS, where storage tanks
are designed to be operated actively (i.e. with the user determining the level of discharge based on the
current weather and forecast), are found to optimise water supply demand and stormwater discharge
reduction of the maximum daily event. In Newcastle, the low supply (rainfall) relative to a higher
Figure 6 | Household stormwater management based on a 3-bedroom house in Newcastle with an 80 m2 roof area, using
Newcastle rainfall data from 2012. (a) Without RMS (Rainwater Management System), (b) passive RMS and (c) active RMS.
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non-potable household water demand (i.e. toilet flushing) yields a low water supply efficiency from
RMS as tanks are likely to be emptied more frequently. However, frequent emptying of tanks
increases the potential for stormwater control as the tanks will have greater capacity to collect
water during future storm events.
UFR research also investigates the natural resources generated by BGI through a study of the
ecosystem functioning and benefits provided by SuDS ponds, comparing them with semi-natural
and ornamental ponds that are also part of BGI networks. The characteristics of suspended particulate matter and water quality significantly impact pond ecology, as well as pollutant transport and
biogeochemical cycling. Nine ponds in Scotland are being regularly sampled (Krivtsov et al. 2019)
to investigate the seasonality of suspended particulate matter, the impact of outside inputs (i.e. rainfall
events) and internal changes within the pond systems. A number of ecological surveys are being
carried out including vegetation, fungi, vertebrates and aquatic invertebrates. Results find that
SuDS ponds have reasonably high species richness, providing an important contribution to ecosystem
services (Figure 7). The number of reliably identified vascular plants at the sites ranged from 16 (Juniper Green) to 92 (RBGE, Royal Botanic Gardens, Edinburgh). The relationship between pond size
and species richness is not clear; the smallest site (Juniper Green) has the lowest number of species
and large ponds such as Inverleith and Blackford have high species richness, yet species richness is
the highest in RBGE, which is a relatively small ornamental pond. Plant biodiversity at BGI ponds,
therefore, is influenced by several factors including area, pond age, planting regimes and pond
maintenance.
Figure 7 | Species richness of vascular plants at nine ponds of varying size in Scotland. RBGE, Royal Botanic Gardens,
Edinburgh.
Interoperability with other systems
Resource use across the flood-drought spectrum, and in particular during exceedance events, can be
enhanced by actively managing connections between a range of infrastructure systems to increase the
functionality of the whole system (i.e. the city) to deal with floods. This introduces the concept of
interoperability: the ability of any water management system to redirect water and make use
of other system(s) to maintain or enhance its performance function during exceedance events
(Vercruysse et al. 2019). Interoperability can progress the adaptive design process from a system
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with single multi-functional assets towards an interoperable ‘system-of-systems’ to enhance flood resilience, bridging the gap between multi-functional and multi-system urban flood management. To
promote and facilitate interoperability in practice, a spatial analysis framework has been developed
to systematically identify flood impact and flood source areas along with opportunity areas for integration of different infrastructure systems to manage surface water (Figure 8). Linking flood hazard
to flood source areas provides insights into the hydrological processes and interactions within the
urban catchment, and can help prioritize locations for flood management intervention. Furthermore,
identification of different types of flood source areas (e.g. wide superficial flooding, local deep flooding), combined with information on infrastructure systems, can guide the selection of appropriate
flood management solutions from a catchment perspective. The analysis framework aims to bring
together stakeholders from diverse organisations, facilitating collaborative projects and aligning
investment in flood management and other infrastructure development projects.
Figure 8 | Conceptual architecture of a spatial mapping tool for system-based flood management aiming to combine two
main aspects: (i) where does flood water come from and how can intervention priority areas be identified; and (ii) where can
flood water (not) go based on the existing infrastructure systems that create opportunities and barriers for interoperability?
(Vercruysse et al. 2019).
THEME 3: FLOOD RISK MANAGEMENT AT THE HEART OF URBAN PLANNING AND DELIVERY
(WP4 AND WP5)
In addition to the engineering advances detailed above, the path to urban flood resilience is characterised by two types of transformative social change. First, planners, developers, design engineers and
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system operators must demonstrate increased awareness of, and responsiveness to, citizens’ physical,
social and environmental needs and preferences. Second, citizens’ attitudes and behaviours to flood
and water infrastructure must change to better understand and appreciate the multiple benefits of
BG þ G innovation.
Understanding public perceptions of BG þ G is a critical step to addressing barriers to their
implementation, gaining support and improving awareness (O’Donnell et al. 2017). Nonetheless,
little work has been done to unpick conflicting attitudes (installations seen as attractive and yet
unsafe) or to understand the gulf between expressed positive attitudes to natural spaces and behaviours around them. For instance, examples of liking the concept of BGI (‘everyone likes a bit of
nature’), but not engaging with proposals for specific spaces or being prepared to fund them suggests
contrasting beliefs and values (Everett & Lamond 2019). Therefore, to enhance understanding of
attitudes and preferences that may affect behaviours around BG þ G, it is necessary to explore the
deepening of traditional stated preference approaches (explicit measures) together with novel tests
that reveal more subconscious attitudes (implicit preferences). Perceptions are typically evaluated
by explicit, or self-report, measures such as questionnaires and Likert scale tests (e.g. Bastien et al.
(2012)). However, these approaches assume that respondents know and can articulate their beliefs
and have an internal concept of BG þ G and SuDS that they consciously base their attitudes on.
The limited public awareness of the functionality of SuDS, and frequently encountered issues with
respondents giving more ‘socially acceptable’ responses of ‘liking’ all types of blue-green space,
suggests added value of social psychology techniques, such as Implicit Association Tests (IAT).
IATs measure hidden perceptions and negate issues of social desirability bias, self-enhancement
bias, and self-ignorance bias common with explicit tests. The IAT reveals implicit attitudes by measuring the strengths of associations between stimuli (e.g. images of blue and green space) and evaluative
attributes (e.g. good and bad words) based on reaction times. IATs have been used in environmental
research evaluating, for example, implicit connectedness with nature (Liu et al. 2019), and are being
trialled by the UFR Consortium to help identify some of the underlying implicit attitudes towards the
use of blue, green and grey space that may exert a significant influence on public preferences (Fenner
et al. 2019).
The effectiveness of contemporary models of community engagement have also been evaluated.
The specific challenges inherent in engagement around BGI suggest that engagement frameworks
need to draw on elements of good practice from urban planning and flood risk management to
enhance understanding of the long-term need for BGI across diverse communities, and to maximise
the multiple benefits that may be delivered. It was observed that such a framework for BGI was
lacking. Drawing on fundamental principles that BGI engagement needs go beyond tokenism in
order to achieve the required goals (Arnstein 1969), a typology of BGI-community engagement
based on different levels of acceptance and influence was developed and applied to case studies of
existing practice (Everett & Lamond 2018). Five fundamental principles to guide more effective
BGI engagement and encourage a greater sense of ownership, appreciation and care around BGI
have been developed. These focus on both outcomes and processes, to ensure the enablement of
longer-term engagement with functional and amenity aspects of the proposed measures:
• People: necessitating two-way engagement building capacity and awareness, but also highlighting
the importance of practitioners’ knowledge of communities’ perceptions, interests and needs.
• Design: preference for BGI that fit into the local context, provide multiple benefits (that are valued
by the community) and are low maintenance.
• Power: community engagement should not reinforce existing social inequalities but should improve
community integration where possible and recognise existing power relationships.
• Procedure: BGI establishment should be collaborative, efficient and sustainable, considering all
community perspectives (where given) to deliver co-designed BGI.
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• Engagement: local understanding and participation should be developed, to ensure that different
communities’ perspectives are heard and encourage democratic outcomes.
These concepts are being further developed to understand the inherent multiplicity of ‘communities’; not simply communities of place and of practice, but also of circumstance, interest and
action (Meikle & Jones 2013) that will require consideration and appropriate modes of engagement.
The use of Social Practice Theory reveals that such thinking can help identify communities with
specific capacities or interests, and improve understanding of their motivations and perceptions
towards BGI.
The governance and political issues around flood and water management and planning are also
being investigated, focussing on the implementation of SuDS through England’s strengthened planning system. We are investigating barriers to innovation within the planning process and how
planners may play the crucial collaborative role and achieve consensus in strategic land-use decisions
on BG þ G infrastructure. The Government announcement in 2014 that SuDS would be implemented
though a strengthened planning system, instead of via enactment of Schedule 3 of the 2010 Flood and
Water Management Act (FWMA 2010), can be characterised as a more flexible and adaptive form of
governance, supported by light regulation and using existing arrangements and wide stakeholder
engagement. However, much of the evidence to date suggests that SuDS implementation has been
complex, resulting in suboptimal uptake (LI & CIC 2019), and ambiguous and noncommittal legislation. Local authorities typically lack the legislative backing and resources to provide valuable
incentives to developers to implement SuDS and issues over ongoing maintenance arrangements
remain firm barriers. Monitoring progress with the introduction of Schedule 3 in Wales (January
2019), located on the other side of the governance spectrum to strengthened planning policy, presents
an opportunity for comparative research to examine these two approaches to governance and implications for SuDS and BGI, in addition to wider environmental and societal gains.
LEARNING AND ACTION ALLIANCES (LAA) TO ALIGN RESEARCH OUTPUTS WITH PRACTITIONER
NEEDS
The final objective of the UFR Consortium is to embed research in the primary case study cities (Newcastle and Ebbsfleet) through Participatory Action Research and co-produce strategies to overcome
the myriad socio-political, governance and biophysical barriers to BG þ G innovation. The Learning
and Action Alliance (LAA) framework has been developed to meet this objective. Local stakeholders
in Ebbsfleet and Newcastle regularly meet to discuss innovative BG þ G solutions to flood and water
management challenges that align with a range of stakeholder objectives. The intention is for these
co-produced solutions to be subsequently incorporated into practice and policy (Table 1). LAAs are
a response to increasingly louder calls for integrated solutions to ‘wicked problems’; communal
problems that cannot be solved by science or traditional top-down governance alone, and are
beyond the remit of individual stakeholders or organisations. LAAs typically have an atmosphere
of mutual ownership that permits open discussion, rational criticism and co-production of knowledge
to create a joint understanding of a problem and its possible solutions (Ashley et al. 2012). The Newcastle LAA has focussed on enhancing the evidence base, and sharing best practice of, BG þ G flood
and water management projects in the NE region, suggesting alternatives to traditional schemes when
opportunities arise and helping move the city forward in its ambition to become a ‘Blue-Green City’.
This is exemplified in the ‘Newcastle Declaration on Blue and Green Infrastructure’ that commits
signatory organisations to greater implementation of BGI, collaborative working and a move towards
partnership funding strategies. The Declaration was relaunched in 2019 with ten signatory organisations from a range of disciplines, including flood and water management, planning, ecology, estate
management and water resources (UFR 2019). In Ebbsfleet, the LAA has developed a system
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Table 1 | Characteristics of the Newcastle and Ebbsfleet Learning and Action Alliances (LAA)
Location
Newcastle LAA
Newcastle upon Tyne
Ebbsfleet LAA
Ebbsfleet Garden City, Kent
Established
2014
2017
Key issue
Innovative flood risk management solutions
Sustainable water use in the Garden City
Core stakeholders
Newcastle City Council, Northumbrian Water,
Environment Agency, Newcastle University,
consultancies (e.g. Arup, Royal HaskoningDHV,
Stantec), major landowners
Ebbsfleet Development Corporation, Southern and
Thames Water, Local Authorities, Kent County
Council, Environmental NGOs
Current focus
Promoting Blue-Green infrastructure in Newcastle
flood and water management practice and policy,
opportunistic intervention, dissemination of best
practice BG þ G
Development of a system dynamics model that
investigates current and future water use in
Ebbsfleet
Impact
Incorporation of Blue-Green infrastructure in policy, The model will be used to generate future water
use scenarios and provide a policy basis for
e.g. Newcastle Local Flood Risk Management
future local policy making. It will also provide
Plan (Newcastle City Council 2016), Newcastle
input to the Ebbsfleet Water Strategy, developed
City Strategic Surface Water Management Plan,
with Ebbsfleet Development Corporation
Newcastle Blue and Green Declaration (UFR
2019)
Note the different dates of establishment and longer operating period of the Newcastle LAA, and hence, potential for greater impact and outputs to date.
dynamics model to investigate water use options for the Garden City. The primary objective is to
reduce residential potable water use, enabling greater resilience to the risk of future water scarcity
and drought. Outputs from model scenarios under a range of future climate and socio-economic conditions will provide options for alternative stormwater management, including RWH and greywater
reuse, more water efficient behaviour, and enhance the capacity of local stakeholders to influence
policy in a more sustainable direction. The system dynamics model is also a catalyst for bringing stakeholders to the table, helping align their agendas around a common issue to create a sustainable
vision for Ebbsfleet.
DISCUSSION AND CONCLUDING REMARKS
Transformative change in practice, policy and governance of flood and water management is necessary
if global cities are to progress along the blue-green path to achieving urban flood resilience. Planning,
design and implementation of urban water systems must be reconfigured towards greater water-sensitive urban design and multifunctional BG þ G infrastructure to effectively manage urban water
under future climates characterised by more extreme weather events, and under future development
scenarios whereby increased urbanisation stresses drainage infrastructure and reduces permeable
greenspace in cities. UFR research contributes to the growing evidence base to support the case for multifunctional BG þ G infrastructure that delivers multiple environmental, societal and economic
benefits, and enhances urban flood resilience by bringing water management and green infrastructure
together to create Blue-Green Cities. The main outputs (to date) and planned deliverables from ongoing
research are now discussed in relation to their potential impact on current practice and policy.
Key to creating future flood-resilient cities is the development of BG þ G systems that may be
co-optimised to maximum flood risk reduction, while delivering multiple co-benefits, under a range
of future scenarios that account for climate and socio-economic change. The adaptation pathways
approach that we present provides the rational basis on which to plan (long-term) and deliver
urban water resilience in an uncertain future. The methodology and guidance on assessing a range
of flexible adaptation pathways that has been developed by the UFR project allows the most effective
mix of BG þ G systems in any given location at any time to be determined according to site-specific
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characteristics and requirements. The innovation for practice and policy lies in the evaluation of
pathways rather than options in separation, and the co-valuation of multiple benefits. The approach
(termed ‘adaptive pathways’) is promoted in the Draft National Flood and Coastal Erosion Risk
Management Strategy for England as a mechanism to help places plan and adapt to flooding and
coastal change across a range of climate futures (Environment Agency 2019), suggesting that there
is already interest from policy-makers and practitioners in this approach to delivering flood resilience.
Developing urban flood and water management systems with the adaptive capacity essential to
keep flood risk at acceptable levels however climate changes are further dependent on accurate modelling of urban hydrosystems that bridge the interfaces between urban/rural and engineered/natural
hydrosystems. The CityCAT/SHETRAN combination presented in this paper advances current
hydrosystems modelling by providing a physical basis for simulating the effects of land-use change,
BG þ G implementation, and climate change on runoff and water storage. The inclusion of antecedent conditions are crucial to understanding how a range of wet and dry soil conditions impact the
runoff fraction and how, and when, a rainstorm may turn into an urban flood. The creation of
impact maps from such modelling may provide a rapid assessment tool for flood risk practitioners,
and identify appropriate location-specific BG þ G infrastructure combinations based on how they
impact local hydrosystems.
The importance of integration between urban water and other infrastructure systems is a concurrent
theme in UFR research. The creation of interoperable BG þ G infrastructure systems that aim to
increase the functionality of the whole system (i.e. the city), and increase urban flood resilience
while meeting the objectives of stakeholders working within other urban systems, e.g. transport
and energy, is an exciting area of research within the UFR project. The spatial analysis framework
that we present (described in greater detail in Vercruysse et al. (2019)) combines several components
of UFR research. CityCAT is used to identify the source-to-impact pathways and help highlight
locations for flood management intervention that will have the most impact on reducing flood
hazard (and damage). Expert local knowledge from Newcastle LAA members further helped identify
specific interoperability challenges in Newcastle. This also demonstrates how UFR research has
become embedded in the Newcastle case study and how the LAA has facilitated social learning
amongst academics and practitioners. By combining flood risk management with spatial information
on urban infrastructure and social, political and environmental characteristics, the interoperability
analysis framework will allow planners to identify opportunities for investment in resilient solutions
for sustainable city development, and is currently being explored with Local Authority input.
UFR research has further investigated the potential for integrating urban water and energy systems,
through the development of a screening tool to assess the feasibility of micro-hydropower generation
from the controlled release of water from SuDS ponds (Costa et al. 2019). Nonetheless, the limited
potential for micro-hydropower in the UK suggests that there are alternative, more effective, ways
to utilise stormwater as a resource, such as RWH, which may provide both flood risk reduction
and drought mitigation benefits at the property scale, with opportunities to upscale those benefits
across urban areas. For RWH to reach its potential, planners and developers must move away
from ad hoc and localised RWH schemes towards integrated catchment-wide strategies that utilise
RMS to concurrently reduce water demand, stormwater discharge and energy usage. Active RMS
have greater potential to optimise water supply demand and reduce stormwater discharge, as demonstrated by the Newcastle residential example presented here. The success of such systems in practice
would be dependent on the levels of engagement, understanding and commitment by users to
managing the system, which represents an interesting avenue of further research. There is typically
a trade-off between supply efficiency and potential for stormwater control in RMS, influenced primarily by the frequency and severity of rainfall events, suggesting that local conditions would be essential
in designing RMS that were fit for purpose in different parts of the UK. Conjunctive SuDS-Managed
Aquifer Recharge systems may also be a viable option for addressing both stormwater management
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and drought mitigation, depending on hydrogeology and urban context, and is currently being
investigated by the UFR Consortium.
Shifting the research focus to the interfaces between planners, developers, engineers and beneficiary communities, the final UFR research theme addresses the need for greater awareness of, and
responsiveness to, citizens’ physical, social and environmental preferences, and investigates how
interactions between responsible authorities and stakeholders must evolve to enable cities to achieve
flood resilience in ways that are sustainable and enduring. Novel measures that determine implicit
preferences for BGI and SuDS have been developed that reveal insight into subconscious attitudes
towards BG þ G that may be used to improve public acceptability of features via better design
(Fenner et al. 2019). IATs have the potential to help planners and policy-makers understand conflicting attitudes towards BGI that may not be captured by explicit measures, such as questionnaire and
interviews, which are commonly used to survey public perceptions. For example, positive attitudes
towards attractiveness of BGI may be offset by concerns over safety or perceived tidiness (which is
highly subjective and based on how one values different types of nature, i.e. manicured vs. wild).
Understanding what influences implicit perceptions can guide planners and designers to solutions
that are more highly valued and accepted. Greater sense of ownership, appreciation and care
around BGI may also be encouraged by more effective BGI community engagement, which may
be achieved by following the five fundamental principles outlined herein. Longer term engagement
with potential beneficiary communities regarding the functional and amenity aspects of BGI are
essential to build both capacity and awareness of communities and develop BGI designs that fit
into the local context (environmental and socio-economic) and provide multiple benefits that are
acknowledged and valued. BGI community engagement in flood-resilient cities would be founded
on collaboration and co-design between practitioners’ and communities’, improved community
integration, inclusion of a range of community perspectives (including, where possible, the voices
of groups that are typically perceived as disengaged), and a reduction in social inequalities through
equitable access to quality blue-green space.
The transition towards flood-resilient cities is also dependent on changing how integrated systems
of BG þ G and planned, delivered and maintained. Ongoing comparative research into SuDS
implementation under (a) strengthened English planning policy, which, to date, has resulted in
suboptimal uptake, and (b) introduction of Schedule 3 in Wales in January 2019, will reveal interesting insights into the effectiveness of these approaches to governance, and help policy-makers and
practioners understand where future challenges, and opportunities, lie. LAAs are also advocated as
frameworks to help make the aspirations of multi-objective planning policies deliverable in practice
by bringing together a range of invested stakeholders to debate, contest and ultimately co-produce
multifunctional BG þ G solutions to current challenges related to flood and water management,
sustainability, wellbeing and climate change adaptation. The signing of the ‘Newcastle Declaration
on Blue and Green Infrastructure’ by Newcastle LAA member organisations is positive proof that
UFR research is being delivered through the LAA in a way that results in transformative change
and supports Newcastle’s progress towards becoming a flood-resilient city.
ACKNOWLEDGEMENTS
This research was performed as part of an interdisciplinary project undertaken by the Urban Flood
Resilience Research Consortium (www.urbanfloodresilience.ac.uk). This work was supported
by the Engineering and Physical Sciences Research Council (grant numbers EP/P004180/1, EP/
P003982/1, EP/P004210/1, EP/P004237/1, EP/P004261/1, EP/P004296/1, EP/P004318/1, EP/
P004334/1, and EP/P004431/1). The associated data and metadata are available at 10.17639/
nott.6185.
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REFERENCES
Arnstein, S. R. 1969 A ladder of citizen participation. Journal of the American Institute of Planning 35, 216–224. doi:10.1080/
019443.
Ashley, R., Blanskby, J., Newman, R., Gersonius, B., Poole, A., Lindley, G., Smith, S., Ogden, S. & Nowell, R. 2012 Learning and
action alliances to build capacity for flood resilience. Journal of Flood Risk Management 5, 14–22. doi:10.1111/j.1753318X.2011.01108.x.
Bastien, N. R. P., Arthur, S. & McLoughlin, M. J. 2012 Valuing amenity: public perceptions of sustainable drainage systems
ponds. Water and Environment Journal 26, 19–29. doi:10.1111/j.1747-6593.2011.00259.x.
Behzadian, K. & Kapelan, Z. 2015 Modelling metabolism based performance of an urban water system using WaterMet2.
Resources, Conservation and Recycling 99, 84–99. doi:10.1016/j.resconrec.2015.03.015.
Buurman, J. & Babovic, V. 2016 Adaptation pathways and real options analysis: an approach to deep uncertainty in climate
change adaptation policies. Policy and Society 35, 137–150. doi:10.1016/j.polsoc.2016.05.002.
Campisano, A., Butler, D., Ward, S., Burns, M. J., Friedler, E., DeBusk, K., Fisher-Jeffes, L. N., Ghisi, E., Rahman, A. & Furumai,
H. 2017 Urban rainwater harvesting systems: research, implementation and future perspectives. Water Research 115,
195–209. doi:10.1016/j.watres.2017.02.056.
Costa, J., Fenner, R. A. & Kapetas, L. 2019 Assessing the potential for energy recovery from the discharge of storm water run-off.
Proceedings of the Institution of Civil Engineers-Engineering Sustainability 1–11. doi:10.1680/jensu.18.00035.
Environment Agency 2014 Flood and Coastal Erosion Risk Management Long-Term Investment Scenarios (LTIS). Environment
Agency, Bristol.
Environment Agency 2019 Draft National Flood and Coastal Erosion Risk Management Strategy for England. Available from:
https://consult.environment-agency.gov.uk/fcrm/national-strategy-public/user_uploads/fcrm-strategy-draft-final-1-may-v0.
13-as-accessible-as-possible.pdf (accessed 3 July 2019).
Everett, G. & Lamond, J. E. 2018 Considering the value of community engagement for (co-) producing blue–green
infrastructure. WIT Transactions on the Built Environment 184, 1–13. doi:10.2495/FRIAR180011.
Everett, G. & Lamond, J. 2019 Green roof perceptions: Newcastle, UK CBD owners/occupiers. Journal of Corporate Real Estate
21 (2), 147–164. doi:10.1108/JCRE-11-2017-0044.
Ewen, J., Parkin, G. & O’Connell, P. E. 2000 SHETRAN: distributed river basin flow and transport modeling system. Journal of
Hydrologic Engineering 5, 250–258. doi:10.1061/(ASCE)1084-0699(2000)5:3(250).
Fenner, R. A. 2017 Spatial evaluation of multiple benefits to encourage multi-functional design of sustainable drainage in bluegreen cities. Water 9, 953. doi:10.3390/w9120953.
Fenner, R. A., O’Donnell, E., Ahilan, S., Dawson, D., Kapetas, L., Krivtsov, V., Ncube, S. & Vercruysse, K. 2019 Achieving
urban flood resilience in an uncertain future. Water 11, 1082. doi:10.3390/w11051082.
Fewkes, A. & Butler, D. 2000 Simulating the performance of rainwater collection and reuse systems using behavioural models.
Building Services Engineering Research and Technology 21, 99–106. doi:10.1177/014362440002100204.
FWMA 2010 Flood and Water Management Act, 2010. Elizabeth II. Chapter 29. Her Majesty’s Stationery Office, London, UK.
Gersonius, B., Ashley, R., Jeuken, A., Pathinara, A. & Zevenbergen, C. 2015 Accounting for uncertainty and flexibility in flood
risk management: comparing real-in-options optimisation and adaptation tipping points. Journal of Flood Risk
Management 8, 135–144. doi:10.1111/jfr3.12083.
Glenis, V., Kutija, V. & Kilsby, C. 2018 A fully hydrodynamic urban flood modelling system representing buildings, green space
and interventions. Environmental Modelling & Software 109, 272–292. doi:10.1016/j.envsoft.2018.07.018.
Hallegatte, S. 2008 An adaptive regional input-output model and its application to the assessment of the economic cost of
Katrina. Risk Analysis: An International Journal 28, 779–799. doi:10.1111/j.1539-6924.2008.01046.x.
House of Commons 2015 Commission of Inquiry Into Flood Resilience of the Future Titled ‘Living with Water’. All Party Group
for Excellence in the Built Environment. House of Commons, London, p. 32, para. 3. http://cic.org.uk/admin/resources/
appg-report.-1-1.pdf.
Krivtsov, V., Arthur, S., Buckman, J., Bischoff, J., Christie, D., Birkinshaw, S., Takezawa, K., Chamberlain, D. & Pereira, R. 2019
Monitoring and modelling SUDS retention ponds: case studies from Scotland. In: ICONHIC 2019, 23–26th June 2019,
Chania, Greece.
Lashford, C., Rubinato, M., Cai, Y., Hou, J., Abolfathi, S., Coupe, S., Charlesworth, S. & Tait, S. 2019 SuDS & sponge cities: a
comparative analysis of the implementation of pluvial flood management in the UK and China. Sustainability 11 (1), 213.
doi:10.3390/su11010213.
Lawson, E., Thorne, C., Ahilan, S., Allen, D., Arthur, S., Everett, G., Fenner, R., Glenis, V., Guan, D., Hoang, L., Kilsby, C.,
Lamond, J., Mant, J., Maskrey, S., Mount, N., Sleigh, A., Smith, L. & Wright, N. 2014 Delivering and evaluating the
multiple flood risk benefits in blue-green cities: an interdisciplinary approach. WIT Transactions on Ecology and the
Environment 184, 113–124. doi:10.2495/FRIAR140101.
LI & CIC 2019 Achieving Sustainable Drainage. A Review of Delivery by Lead Local Flood Authorities January 2019
Comissioned by the Landscape Institue and Construction Industry Council. Available from: https://landscapewpstorage01.
blob.core.windows.net/www-landscapeinstitute-org/2019/01/11689_LI_SuDS-Report_v4a-Web.pdf (accessed 23 January
2019).
Lian, Y., Chan, I.-C., Singh, J., Demissie, M., Knapp, V. & Xie, H. 2007 Coupling of hydrologic and hydraulic models for the
Illinois River Basin. Journal of Hydrology 344, 210–222. doi:10.1016/j.jhydrol.2007.08.004.
Downloaded from https://iwaponline.com/bgs/article-pdf/2/1/28/648025/bgs0020028.pdf
by guest
45
Blue-Green Systems Vol 2 No 1
doi: 10.2166/bgs.2019.199
Liu, T., Geng, L., Ye, L. & Zhou, K. 2019 ‘Mother Nature’ enhances connectedness to nature and pro-environmental behavior.
Journal of Environmental Psychology 61, 37–45. doi:10.1016/j.jenvp.2018.12.003.
Locatelli, L., Mark, O., Mikkelsen, P. S., Arnbjerg-Nielsen, K., Deletic, A., Roldin, M. & Binning, P. J. 2017 Hydrologic impact of
urbanization with extensive stormwater infiltration. Journal of Hydrology 544, 524–537. doi:10.1016/j.jhydrol.2016.11.030.
Manocha, N. & Babovic, V. 2017 Development and valuation of adaptation pathways for storm water management
infrastructure. Environmental Science & Policy 77, 86–97. doi:10.1016/j.envsci.2017.08.001.
Meikle, H. & Jones, D. 2013 Pedagogy of oppressed community engagement: Socially inclusive visioning of urban change.
In: Proceedings of the State of Australian Cities Conference (Ruming, K., Randolph, B. & Gurran, N., eds). State of
Australian Cities, Sydney, NSW, pp. 1–13.
Newcastle City Council. 2016 Local Flood Risk Management Plan. Available from: https://www.newcastle.gov.uk/sites/default/
files/wwwfileroot/environment-and-waste/flood-management-newcastle/2016.03.31_complete_and_final_rpt_-_lfrmp_
march_2016_1.pdf (accessed 22 March 2019).
Nguyen, P., Thorstensen, A., Sorooshian, S., Hsu, K., AghaKouchak, A., Sanders, B., Koren, V., Cui, Z. & Smith, M. 2016 A high
resolution coupled hydrologic–hydraulic model (HiResFlood-UCI) for flash flood modeling. Journal of Hydrology 541,
401–420. doi:10.1016/j.jhydrol.2015.10.047.
O’Donnell, E., Lamond, J. & Thorne, C. 2017 Recognising barriers to implementation of blue-green infrastructure: a Newcastle
case study. Urban Water Journal 1–8. doi:10.1080/1573062X.2017.1279190.
O’Donnell, E., Lamond, J. & Thorne, C. 2018 Learning and action alliance framework to facilitate stakeholder collaboration
and social learning in urban flood risk management. Environmental Science & Policy 80, 1–8. doi:10.1016/j.envsci.2017.
10.013.
Sharma, A., Pezzaniti, D., Myers, B., Cook, S., Tjandraatmadja, G., Chacko, P., Chavoshi, S., Kemp, D., Leonard, R. & Koth, B.
2016 Water sensitive urban design: an investigation of current systems, implementation drivers, community perceptions
and potential to supplement urban water services. Water 8 (7), 272. doi:10.3390/w8070272.
Trogrlić, R. Š., Rijke, J., Dolman, N. & Zevenbergen, C. 2018 Rebuild by design in Hoboken: a design competition as a means
for achieving flood resilience of urban areas through the implementation of green infrastructure. Water 10 (5), 553. doi:10.
3390/w10050553.
UFR 2019 Newcastle Blue and Green Declaration. Urban Flood Resilience website. Available from: http://www.
urbanfloodresilience.ac.uk/newcastle-blue-and-green-declaration/newcastle-blue-green-declaration.aspx (accessed 22
March 2019).
UN 2018 World Urbanisation Prospects: The 2018 Revision [Key Facts]. Available from: https://esa.un.org/unpd/wup/
Publications/Files/WUP2018-KeyFacts.pdf (accessed 18 March 2019).
Vercruysse, K., Dawson, D. & Wright, N. 2019 Interoperability: a conceptual framework to bridge the gap between multifunctional and multi-system urban flood management. Journal of Flood Risk Management 12 (S2), e12535. doi:10.1111/
jfr3.12535.
Zevenbergen, C., Fu, D. & Pathirana, A. 2018 Transitioning to sponge cities: challenges and opportunities to address urban
water problems in China. Water 10 (9), 1230. doi:10.3390/w10091230.
Downloaded from https://iwaponline.com/bgs/article-pdf/2/1/28/648025/bgs0020028.pdf
by guest