Natural Flood Management

October 2023

Ann Berkeley

Evenlode Catchment Partnership Project Manager

With changing weather patterns due to global warming there has been an increase in heavy rainfall events along with longer hot dry periods. Natural flood management (NFM) is fast becoming a very important tool to combat both flooding issues and drought by helping to regulate water within the catchment.

The Environment Agency is developing a Thames Valley Flood Scheme which will focus on hard engineering solutions to retain large amounts of water in the mid-Thames catchment areas. These will be expensive to construct and will take time to deliver. This might prevent flooding downstream but will do nothing to help those communities in the upper catchments which flood regularly.

The Evenlode Catchment Partnership is working to address these issues using natural flood management in the upper catchments. In partnership with Gloucestershire County Council, we are working with landowners upstream of Bledington and Moreton in Marsh.  By installing leaky woody dams and field corner bunds water can be held back during high rainfall events which reduces and delays the peak levels downstream.

Field corner bunds in action

Landowners can also help by increasing the organic matter in their soil which will increase the capacity of the soil to retain water. Many of the landowners along the floodplain are now reverting their arable fields to grass. This will have multiple benefits including sequestering carbon, reducing erosion of soils and keeping nutrients on farms.

Through regular monitoring of our NFM scheme on the Littlestock Brook, it has been thrilling to learn that, not only does this project reduce flooding, but it brings multiple benefits including increased biodiversity.

We are privileged to be able to work with Landowners at a landscape scale, but a recent study by Southern Water in the Isle of Wight has shown that householders given 200L rain storage butts helped to reduced raw sewage spills by 70 per cent, and the company plans to introduce similar trials across Kent, Hampshire and East Sussex.

A water butt rapidly fills up during prolonged rainfall. In the version deployed by Southern Water, a drain halfway up the receptacle releases a lot of the water into the network over a five-hour period. However, releasing the water into a soakaway would be even more beneficial. Unlike other butts, this leaves a space in the drum for the next time it rains. The water collected can also be used in the garden, which not only provides better quality water for the plants but helps reduce demand in dry spells.

Could you fit a rain butt onto a roof downpipe?

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