Nature-based Solutions to the Management of Rainwater and Surface Water Runoff in Urban Areas – Best Practice Interim Guidance Document

Extreme rainfall events are becoming more frequent as we increasingly see the effect of climate change on the environment. If we do not manage the flow of surface water in urban areas, there will be a significant increase in both the level of pollution entering water bodies from urban runoff and the risk of flooding.

This document is for all urban planning and design professionals and outlines how to move towards a more systematic and sustainable approach to urban planning through water sensitive urban design. It identifies the need for a significant change in the way we plan, design, build and maintain our urban areas through the replacement of impermeable surfacing with nature-based planted areas designed to absorb, retain, store and treat urban runoff prior to discharge back to the environment. It is driven by three main factors:

• Environmental: the impact of urban runoff on water quality (Water Framework Directive objectives)
• Climate Change: weather and rainfall patterns have already significantly changed with increased experience of high-intensity localised rainfall events (rainwater management)
• Flood Risk: increased rainfall intensity and increasing levels of impermeable urban surfacing combine to increase the risk of urban flooding. There is an urgent need to address this by retaining rainwater as close as possible to where it occurs within a catchment.

This document demonstrates how through appropriate changes to the way we plan and design urban areas, we can address these related issues. It promotes the use of long-term and plan-led approaches that combine nature-based solutions with spatial planning, particularly at the level of the individual urban settlement, large or small. Climate change, and the need to adapt our urban areas to a changed climate in terms of rainfall patterns is the unifying concept in terms of the scope of this document.