These are structures that are built from logs and woody material across rivers or streams to slow and hold back water during storm and flood events. They often form naturally across watercourses when there is enough surrounding woodland, but we can intervene in places to mimic and encourage these natural processes.
Leaky wooden dams slow, divert and store flood water and allow increased infiltration into surrounding soils. They are designed to let normal river flows and aquatic wildlife pass through underneath. When river levels rise, some water becomes trapped behind the dams, filling the river channel behind, and spreading onto surrounding land in severe floods.
After storms pass and river levels recede, all water passes under the dams unimpeded once again.
A network of several leaky wooden dams, along with other Natural Flood Management (NFM) measures in the catchment, can hold back enough water to reduce flood risk to properties and land downstream. These natural solutions often work well with existing flood mitigation measures in the catchment like flood banks and property flood protection measures.
Natural solutions are crucial to help reduce damage and disruption from the intense and frequent flood events we are seeing across the River Derwent Catchment, including to properties, businesses, wildlife habitats and agricultural land.
As well as reducing flood risk, natural flood management measures provide multiple other benefits. Locally, they create an attractive landscape for communities and residents with more natural features, improving health and well-being. The wetter landscape also improves drought resilience and can allow different vegetation and habitats for wildlife to thrive, improving biodiversity. Over time, these natural and diverse environments store more carbon in the soil, trees and vegetation, which helps mitigate climate change.
Derbyshire Wildlife Trust have been working with Cavendish Golf Club, which lies just upstream of Buxton in the Peak District. The golf course and surrounding land is home to the upper part of the Derbyshire River Wye, which flows into the River Derwent.
With support from the landowners, several small leaky wooden dams were installed on tributaries of the River Wye during the 2022-23 winter season. In March 2024, Derbyshire Wildlife Trust installed four larger leaky wooden dams on the River Wye itself.
The dams were largely created from local natural woody material. Trees used for the construction were carefully selected to minimise short-term disruption on wildlife and habitats. Construction took place in the late winter season with ecological surveys beforehand. Some trees and branches used were suffering from ash die-back disease and others were selected from densely planted woodland areas. Narrow trenches and fence posts help secure the wooden logs in place on both sides of the river.
Natural flood management measures including leaky wooden dams form part of the Derwent Living Forest vision, where 30,000 hectares of wetland and wooded habitats are being created by 2050. This will provide connectivity for the movement of species across the Derwent River Catchment between the National Forest and planned Northern Forest. This connectivity will provide resilience against climate change and extreme weather events.
For more information on Natural Flood Management (NFM) measures, please see our Nature Based Solutions page by clicking on the button below:
