Green Cities and Blue-Green Infrastructure

Green Cities aim to design cities more sustainably, efficiently, adaptive, and resiliently, recognizing connections between different sectors and supporting development strategies that benefit society and urban ecosystems. In urban water resource management, a Blue-Green City ensures holistic planning and management of water, wastewater, and stormwater across the city. This approach enhances resilience to climate change and extreme weather events while ensuring the health of aquatic ecosystems.

Limitations of Traditional Urban Water Management

However, traditional urban water management relies on grey infrastructure like dams and levees, leading to environmental and economic issues. These systems, designed to prevent local flooding, often cause downstream flooding and stormwater overflows. They disrupt the local hydrological cycle, affecting water availability for humans and nature, and struggle with climate change-induced extreme weather events. They also degrade water quality by washing pollutants into waterways. Urbanization and climate change are causing environmental degradation and regulatory challenges in managing floods and restoring waterway health.

Blue-Green Infrastructure in Urban Water Management

In a Blue-Green City, BGI involves using natural or human-made systems to enhance ecosystem services in managing water resources and increase resilience to climate risks. BGI solutions can also be used to support the goals of multiple policy areas. For example, green spaces and restored lakes and wetlands can reduce flooding risks to neighbourhoods while supporting urban agricultural production and wildlife and providing recreational and tourism benefits.

Examples of Fiscal and Non-Fiscal Tools for BGI Implementation

In Blue-Green Cities, urban water managers also use a variety of innovative fiscal and non-fiscal tools to encourage the implementation of BGI on public and private property to manage water resources and increase resilience to climate risks sustainably:

  • Berlin's water utility, Berliner Wasserbetriebe, charges a rainwater fee of EUR 1.797 per square meter per year for drained ground. The fee is based on the impervious area that discharges surface water into the public sewer system. However, BGI features can lead to a partial or even total exemption from this charge.
  • New York City's Department of Environmental Protection's Green Infrastructure Grant Program funds green roof retrofits for stormwater management. The application process is ongoing, with workshops throughout the year. Funding is based on green roof area and soil depth, with a minimum project amount of $50,000.
  • The Brisbane Green Factor, developed by Brisbane City Council, is a voluntary tool for enhancing stormwater quality. It encourages green urban development, including using green infrastructure that aids in stormwater management. By improving stormwater runoff, the tool contributes significantly to the city's sustainable development goals and aligns with Brisbane's vision of being a lush, green, sub-tropical metropolis.

Conclusion: The Value of Blue-Green Infrastructure

In conclusion, BGI offers a sustainable approach to managing water, wastewater, and stormwater in cities. It enhances resilience to climate change and reduces environmental degradation. BGI addresses the shortcomings of traditional grey infrastructure and provides multiple benefits for urban ecosystems. Cities worldwide are recognizing the value of BGI and implementing innovative strategies to encourage its adoption. As urban centres continue to grow, the shift towards a Blue-Green City model is desirable and essential for the health of our planet and future generations.