The effects of NFM are well understood in principle, but demonstrating NFM impacts in large catchments has been difficult due to a wide range of other factors which can influence flow, such as variations in rainfall and land-use. Smaller headwater catchments are more easily characterised and therefore offer a unique opportunity to develop our understanding of the impacts of NFM measures.
Our previous work has demonstrated that restoration though re-vegetation and gully blocking roughens the ground’s surface, which slows the flow of water across the hillslope. This significantly delays and reduces the magnitude of flood peaks during rain storms and can reduce flood risk downstream.
Currently, the extensive upland restoration works being carried out across the UK are funded outside of the flood defence budgets. The primary aim of these works is often to stabilise the landscape and increase biodiversity, so even if restoration measures do reduce flood risk, they are not always recognised and accounted for in NFM assets. It is also unclear whether current restoration practices offer a cost-effective solution to NFM.