Flood Catchment Management at Llangloffan Fen Nature Reserve

Work being carried out on Llangloffan Fen nature reserve

Work being carried out on Llangloffan Fen nature reserve

Dams made of nearby willow

Dams made of nearby willow

Llangloffan Fen nature reserve has recently benefitted from a partnership project with, and funded by, Natural Resources Wales to help slow water flows and raise water levels on the site. The project also aids commitments to improving waterbodies under the Water Framework Directive.

These works go some way in reducing the impacts of floods further down the river catchment by slowing flows and enabling the surrounding wetland to hold more water. Amphibians, invertebrate species and aquatic plants along with fen and reedbed habitats found within the wetland reserve will also benefit greatly. Areas of open water will be extended which also provide valuable habitats for waders and other bird life.

Soft engineering methods were used in this project where river flood management regimes work with natural river processes. They tend not to involve major construction work which was the case here. Total funds available for the works were £5,000 and so with this 14 log dams were created along the top 300m of the 800m canalised length of stream that runs through the reserve. These dams involved felling nearby willow and alder into the stream, piling with brash and staking down with metal rods. They do not completely block the flow of water, rather slow it down and redirect it towards the opposite bank. In time the stream will begin to meander and thus slow flows further. Water levels within the stream are also raised slightly which enhances the surrounding wetland and reduces the impact of larger flows further downstream and into the rest of the Cleddua river system.

A channel was also dug on one of the only remaining meanders of the stream that, with high water flows, will fill and feed water into the wetland, again reducing volumes passing into the stream and further down the catchment.

The Wildlife Trust is grateful for the funding and expertise provided by Natural Resources Wales for this project and we shall continue to monitor how the structures work, strengthening and maintaining when and where necessary.

Nathan Walton

Wildlife Trust Officer, Pembrokeshire