Delivering and Evaluating Multiple Flood Risk Benefits in Blue-Green Cities
University of Nottingham

Research Project Outcomes

The Blue-Green Cities Research Project (2013-2016) has produced a range of outcomes for academics and practitioners, summarised in the Blue-Green Cities Key Project Outputs Summary (5.8 MB PDF file icon) and highlighted below. 

Multiple Benefit Evaluation

A GIS Multiple Benefit Toolbox has been developed to assesses the benefit uplift to an area of a proposed, or pre-existing, Blue-Green infrastructure or SuDS scheme. The toolbox considers the local context (i.e. pre-existing and post-project environmental and social conditions) to provide location and context-specific evaluations of the spatial extent of benefits and how their intensity changes with distance from the infrastructure. See Hoang et al., 2016


A new framework has been created to characterise the uncertainties and barriers to widespread implementation of Blue-Green infrastructure; in our Portland case study, the socio-political uncertainties, including public preferences and political will to champion Blue-Green approaches, exerted a much stronger influence on decision making when compared with the biophysical uncertainties (e.g. modelling, future maintenance and service delivery). See Thorne et al., 2015.


A Learning and Action Alliance (LAA) has been established in Newcastle to bring together professional stakeholders to create a joint understanding of flood and water management problems and negotiate possible solutions. The LAA has opened communication channels with those not typically involved in flood and water management, strengthened existing relationships and created opportunities for collaborative working to achieve common goals and potential for joint funding.

Flood inundation modelling

The CityCAT hydrodynamic model has been developed to better represent pluvial flood inundation in urban areas. The model can also fully couple the surface flow with flow in the storm sewer network, for the first time linking gullies/drains and sewer pipes, and model the movement of water through Blue-Green features (e.g. blue-green roofs, retention ponds, permeable paving, swales, water butts), demonstrating that Blue-Green infrastructure can reduce local and downstream flood risk. 

Sediment transport modelling

A 2D hydro-morphodynamic model has been developed to predict flow and suspended sediment dynamics in urban rivers and investigate how restored floodplains and SuDS ponds can attenuate the upstream flood peak, act as a sediment sink and impact on downstream sediment transport. See Ahilan et al., 2016.

Sediment, debris and ecosystems

Detailed understanding of how Blue-Green infrastructure treats fine sediment and key urban pollutants during multiple rainfall-runoff events has been developed, and finds that Blue-Green assets and SuDS provide sediment detention, but not necessarily in the way, or to the level, that existing manuals suggest. Research has also determined the quantity of fine sediment being temporarily deposited within SuDS assets and identified the ecosystem service benefits provided. See Allen et al., 2015.

Behavioural responses of publics

Analyses of questionnaires and interviews with communities have led to increased understanding of people’s perceptions of Blue-Green infrastructure and have identified key benefits (aesthetics, amenity, health and wellbeing). Members of the public value having a voice yet there is a general lack of understanding of wider Blue-Green infrastructure functions and service requirements. See Everett et al., 2015.  

Flood Footprint

A flood footprint damage accounting framework has been developed to measure the total socio-economic impact that is directly and indirectly caused by a flood event. This can be used to optimise investment in Blue-Green infrastructure by identifying the blind-spots in critical infrastructure and vulnerable sectors in economic supply chains and social networks.

Systems of Systems

A series of interdependencies between stormwater management components and the wider urban landscape are defined, including physical, cyber, geographical and logical interdependencies. The effects of these interdependencies on the performance of SuDS and Blue-Green infrastructure, and how SuDS/Blue-Green infrastructure might impact on other aspects of the urban environment, have been identified. A green roof case study is used to demonstrate relational and organisational complexity and the range of benefits that can accrue. See Hoang & Fenner, 2015

Newcastle case study

Tthe team transferred their research to Newcastle in 2015 to evaluate the multiple benefits (environmental, ecological, social and economic) of a) the Newcastle Great Park SuDS ponds, and b) a hypothetical scenario incorporating Blue-Green infrastructure in the urban core and Wingrove ward. The research findings were presented at a Newcastle dissemination event: Improving Flood Resilience: The Blue-Green Advantage


Blue-Green Cities Research Project

Sir Clive Granger Building,
University of Nottingham,
University Park,
Nottingham, NG7 2RD.

Tel. 0115 8468137