Designing green infrastructure and sustainable drainage systems in urban development to achieve multiple ecosystem benefits

Urbanisation is one of the greatest threats to biodiversity and ecological connectivity. Green infrastructure (GI) networks and corridors are promoted as a way to preserve habitat connectivity even in the context of urbanisation. Yet, previous research has a primary focus on the ecological benefits that may be provided by GI networks without also valuing other potential ecosystem services. There has also been a lack of research into how the design of urban developments, including the potential of sustainable drainage systems (SuDS), may contribute to such networks. Using a case study region in south-east England, different development scenarios and urban designs were assessed under metrics quantifying four aspects of GI provision – ecological services, ecological status, ecological connectivity, and proximity to the population. These were then combined into a single score to compare the overall spatiality of GI potential across the region under the different design and development approaches. Three key considerations for planners were found: first, the positive role urban spaces can play, even without SuDS or considering the proximity to the population, in contributing to GI potentials; second, the balance required between different development approaches to manage the trade-offs between each; and third, the range of positive and negative impacts different SuDS infrastructure have on GI potentials under different urban designs.