Reducing flood risk along Swanage streams
- Published:
- 02 December 2025
We have just completed the first phase of work to reduce the risk of flooding along the Swan Brook which runs into Swanage.
The project involves introducing natural flood management (NFM) techniques like building low earth bunds (embankments), creating scrapes (shallow seasonal ponds) and placing leaky dams in ditches. These won’t change the direction of flow, or prevent flooding altogether, but will spread water across the natural floodplain.
Ben Cooke, our Project Officer for Rivers and Coast said:
“We’re using various methods to hold water then gradually release it as it runs off the hillsides. The aim is to prevent storm water from careering down towards Swanage. It’s a more natural way of flood management, replicating obstructions in rivers caused by falling trees or, of course, the eco-engineering done by beavers.”
The six NFM sites are located on tenanted farmland at the headwaters of tributaries that feed into the Swan Brook (which is classified as being in ‘poor’ condition. The farms are Westwood, Spyway and Godlingston Manor, as well as land in Langton Matravers.
One of the methods used is creating leaky dams in ditches, a technique already used on Purbeck’s peatlands. They are made from logs stacked up in ditches and held in place by posts.
In other areas, scrapes and bunds will encourage the water to form temporary ponds, spreading the water across the floodplain. In open fields, a method called ‘surface roughening’ has been used – tree trunks have been pinned to the ground where floodwater is known to run, again slowing the flow.
Monitoring devices have been installed to record the water levels and flow rates so the effectiveness of the different interventions can be measured.
As well as reducing the flood risk, these techniques retain water in areas longer, helping counteract the impact of dry summers. They act as traps, filtering out organic matter, nutrients from dung and sediment that washes off tracks. They also create habitats for a range of wildlife, from dragonflies and aquatic insects to birds.
We are asking local people to help with the project by photographing or videoing the flood measures after storms when the water is visibly flowing on the surface. This will help monitor which interventions are most effective and if any need to be modified. Please email purbeck@nationaltrust.org.uk
The NFM project was funded through a £325,000 grant from the Environment Agency on behalf of the Government’s Department for Environment, Food and Rural Affairs.
