From extreme storms, to changes in the water cycle, the urban environment is becoming more susceptible to environmental change. Many cities around the world are now looking towards Blue-Green infrastructure to manage the impacts of climate change, and make cities better places to live.  

Blue-Green infrastructure are natural and designed landscapes that include water bodies, such as rivers and green spaces that are designed to turn ‘blue’ during rainfall events.  They are used in policies to manage urban flood risk and help cities adapt to climate change by organisations including the Environment Agency and local councils. The social and psychological benefits from visiting Blue-Green spaces makes Blue-Green infrastructure a key part of policies aimed at improving public health.

Swales are often included in urban design to manage surface water. Water travels into the swale where it moves slowly into the ground. This process also improves water quality by removing some of the pollutants. Vegetation in the swale can actively capture carbon dioxide from the atmosphere. Some vegetation can help improve air quality by trapping airborne pollutants. Swales can provide a habitat for wildlife and increase the biodiversity in the city.

Green roofs are a great example of adding Blue-Green infrastructure to urban areas where space is limited. They can catch rainfall and store it in the plants and soil before it later evaporates, reducing flood risk. Green roofs can also make houses warmer by locking heat inside buildings in winter, and reducing the amount of heat entering buildings in the summer. They can reduce surface temperatures by up to 17 degrees Celsius. Like swales, green roofs can improve air quality and support wildlife habitats.

De-culverting urban rivers is the process of uncovering buried urban rivers and streams, and restoring them to more natural conditions. This creates new habitat for plants and animals, helps manage flood risks, and creates new blue-green corridors that connect urban residents with nature.  

A blue-green city brings these components together, using Blue-Green infrastructure to recreate a more natural water cycle at the city scale. Blue-Green Cities protect the hydrological and ecological values of the urban landscape and provide resilient and adaptive measures to deal with flood events.