Emma Wren, Principal hydrologist
Around the world in recent years unprecedented rainfall has triggered extensive flooding, putting lives in peril, damaging property, and impacting local and regional economic output.
Communities in flood-risk areas want more to be done to protect their homes and businesses, but building more defences and higher walls is not always practical or cost-effective.
We can help alleviate flood risks more sustainably if we work with natural processes to manage river catchments. One approach is natural flood management (NFM), defined by the UK’s Environment Agency as “taking action to manage fluvial and coastal flood and coastal erosion risk by protecting, restoring and emulating the natural regulation function of catchments, rivers, floodplains and the coast”.
In other words, flooding by design, rather than by default.
NFM has relatively low operating and maintenance costs compared to traditional hard engineering schemes; it also provides an opportunity to make greater use of the planet’s natural capital.
If landowners and farmers can be persuaded to allow their fields to be flooded, it will create room upstream for rivers to expand naturally during periods of high flows in order to help protect communities downstream.
Another form of NFM is planting trees and creating new woodlands to aid run-off attenuation. Turning pasture to woodland through extensive tree planting could, over time, slow downstream flows and improve flood protection. In towns and cities, we should fully exploit available green spaces to reduce run-off and allow water to soak into the ground, releasing it slowly to reduce flood risk or storing it for use.
Environmental benefits
The wider environmental benefits of such schemes include improved water quality and greater biodiversity in rivers and wetlands, creation/preservation of natural habitats, carbon sequestration, and enhanced landscapes and public realm spaces, which combine to create better places to live. But for farmers the main attraction will probably be soil conservation.
This underlines how important it is to remember that different stakeholders have different priorities. All parties should be consulted, and selling the concept of working with natural processes will mean demonstrating – in clear, jargon-free language – how they and their communities will benefit.
Community engagement will also depend on finding ways to incentivise landowners and rural businesses to provide a flood-risk mitigation service. And incentives or compensation should cater for tenants as well as landowners.