Natural Flood Management

Flooding: a growing risk

Hundreds of thousands of us live and work in areas at risk of flooding,with 165,000 Londoners at risk from rainfall alone. In our towns and cities, we have lost water storage by replacing wetlands with artificially impermeable surfaces stopping water soaking into the ground, so more water flows to drainage networks. And we have straightened our river channels so that they now move water very quickly.

With climate change, the risk of flooding is increasing. Winters are becoming warmer and wetter, and there are also more extreme rainfall events during the summer in London. Conventional hard flood defences can reliably protect communities, but are often very expensive and can harm the environment: destroying aquatic habitat and disrupting natural flood alleviation and water purification processes. Hard defences can also increase the risk of flooding downstream.

 

Natural Flood Management

Healthy river catchments store water in the landscape, in uplands and on natural floodplains, reducing and slowing down the flow of water downstream.

Natural Flood Management (NFM) is the practice of using and enhancing the natural landscape’s ability to do this. The aim is to restore the natural functioning of river catchments, but where that isn’t possible, emulating natural processes. Depending on the local area, that could involve creating storage ponds, planting trees, reducing soil compaction, restoring meandering rivers, creating wetlands, or leaky dams.

NFM trials in several rural areas have been effective, but there are not enough real world case studies.  That is why NFM is now being piloted in greater London to see if it can work as a method to protect homes, businesses and valuable, productive land. Working in partnership with local communities, Thames21 is trialling NFM in four areas in London: north Hillingdon, north Harrow, north Enfield and Havering (in partnership with the Land of the Fanns project).

Local communities have valuable local knowledge of the land which statutory organisations can learn from. We believe that involving communities will lead to better flood-proofing solutions.

 

Working with nature to tackle flooding

By creating many small-scale flooding interventions, we aim to slow the flow of floodwater and store it higher up in river catchments, especially during and after periods of heavy rainfall. Creating natural flood barriers will allow more water to soak into the ground, complement existing flood defences and protect more land, homes, business and infrastructure from flooding in London.

It also has the potential to reduce soil erosion, create more habitat for birds, mammals, fish and invertebrates, to store carbon and improve access to enhanced green space, helping boost wellbeing and quality of life for urbanised communities.

The programme will be intensively monitored and evaluated over the next three years, and the results fed back to DEFRA and the wider public. 

The aim is for what happens in London to help inform best practice nationally on how to respond to the increasingly urgent threat of flooding: how to reduce existing flood risk and future-proof ourselves from the increased flood risk in future.