Developing new Blue-Green futures

Multifunctional infrastructure to address water challenges

There is a recognised need for a fundamental change in how cities tackle urban water challenges and develop visions for ‘Blue-Green’ urban futures; where multifunctional Blue-Green Infrastructure (BGI) creates environmental and societal co-benefits and is delivered by cross-organisational collaborations. The aim of this interdisciplinary research project is to explore how Blue-Green futures may be developed as new forms of environmentally sustainable urban governance.

Futures that embrace Blue-Green principles are characterised by resilient and sustainable flood and water management approaches. These principles (e.g. green roofs, swales, rain gardens, ponds and urban wetlands) enrich society through the provision of multiple co-benefits. These include access to public green spaces, recreational opportunities, aesthetic enhancements, and improved management of environmental processes such as flooding, drought, urban heat, water quality and air pollution.

Four case cities

Cross-country learning on international best practices has been used to inform new Blue-Green futures and establish international benchmarks. We have focused on four cities that are known for their BGI advances yet have different governance approaches, challenges, perceptions and urban water narratives:

  1. Newcastle (UK): Newcastle Declaration on Blue and Green infrastructure;
  2. Rotterdam (the Netherlands): Rotterdam’s Urban Water Plans;
  3. Ningbo (China): Chinese Sponge City programme;
  4. Portland, Oregon (USA): citywide green infrastructure for stormwater management.


We have explored how Blue-Green visions were developed in these cities, what the drivers for these were, and how learning could be applied in other cities. Through an analysis of explicit and implicit preferences and examination of how social learning may build capacity, we investigated how new forms of environmentally sustainable urban governance can be developed to address current water management challenges. For this we conducted a questionnaire (20 participants per case city, an Implicit Association Test (IAT) to investigate Blue-Green or Grey infrastructure preference and semi- structured interviews (12 participants per case city). We disseminated our findings through webinars, blogs, publications (O’Donnell et al., 2021) and a targeted policy paper aimed primarily at local Government.

Key trends

Portland and Rotterdam certainly stand out as cities acknowledged by many of our questionnaire respondents as BGI leaders. Portland; due to its extensive use of green infrastructure to manage stormwater and reduce combined sewer overflows (e.g. the ‘Grey to Green’ initiative), and Rotterdam; through its extensive research and investment into climate change adaptation and pioneering blue, green and grey infrastructure to manage risk and deliver benefits to society. The questionnaire responses suggest a lot of local support for Blue-Green infrastructure in Newcastle and the Chinese Sponge Cities.

Using the Implicit Association Test

Through the development of a novel application of the Implicit Association Test (IAT), this study investigated the perceptions of BGI held by professional stakeholders in four cities with leading BGI programmes and aspirations. Blue-green and grey infrastructure are perceived positively by the sample population suggesting that they are valued components of landscapes, albeit for different reasons. Overall, respondents implicitly and explicitly prefer BGI, and regard it as safer, tidier, more attractive, useful, valuable and necessary. This suggests a widespread acknowledgement of the functionality (or multifunctionality) of BGI and benefits beyond aesthetic value. As an example, BGI may be regarded as of greater necessity when compared with grey infrastructure due to its ability to reduce vulnerability to other climate change risks beyond flooding such as heat stress and water shortages. Exploring implicit perceptions of integrated systems of blue-green-grey infrastructure designed to address climate change adaptation objectives is an important direction for future research.

Source: Dolman, N. (Royal Haskoning DHV). 2021. Developing new Blue-Green futures: Multifunctional infrastructure to address water challenges. Sustainable built environment and governance through actor-led processes, Reuse, Recycle & Recover. AIWW 2021

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