What impact do nature-based solutions have on reducing flood risks and improving water quality?

Nature-based solutions work with natural processes to manage water. Examples include restoring wetlands and floodplains, planting trees, adding rain gardens to streets, and using permeable surfaces that let rain soak into the ground.

For flood risk, these features can slow, store, and spread runoff rather than sending it straight into drains and rivers. Wetlands and floodplains hold water temporarily; tree canopies and healthy soils absorb some rainfall; and rain gardens can reduce the volume and speed of urban stormwater runoff. Used together across a catchment, these measures may ease pressure on drainage systems and reduce some local flooding.

They can also improve water quality. As water filters through soil and vegetation, particles settle out and plants and soil microbes can take up or break down some pollutants. That can reduce sediment, nutrients, and certain contaminants reaching streams and lakes. Restored wetlands, in particular, can provide valuable wetland flood storage while supporting this natural filtering.

The benefits depend on the site and the size of the storm. A small rain garden will not prevent flooding from an extreme event, and poorly designed features can become clogged or fail to drain. Nature-based measures are most effective when matched to local soils, pollution sources, and flood pathways, maintained over time, and combined with suitable drainage or other flood defenses where needed. They reduce risk and pollution; they do not eliminate either.