HAMPSHIRE Wildlife Trust has raised concerns about how a new flood management scheme will work.

The trust fears the Durngate Flood Alleviation Scheme in Winchester “must be careful not to do more harm than good”.

It is worried that use of the new sluice gates being built at Durngate could damage the adjacent Winnall Moors nature reserve.

The sluices, due to be finished by Christmas, will manage the flow of water through the city but will also cause parts of Winnall Moors to flood to a greater depth and over a wider area.

In 2014 and 2020 Winchester was flooded, and this summer the city council began Phase Two of their flood alleviation scheme.

The trust says the council has committed to only allowing the nature reserve to flood when necessary and in a carefully controlled way but it is urging the council to make sure that they follow through on this promise.

The Trust says it supports the scheme but flooding too often or at the wrong time of year, particularly in spring or summer, could kill plants, swamp birds’ nests and cause species like the water vole to lose their homes.

The scheme could have a detrimental impact on the ecology of the Moors, which are protected as a Site of Special Scientific Interest (SSSI) and a Special Area of Conservation (SAC). The trust has been working closely with Natural England and the Environment Agency to ensure guidance is followed, that will monitor and protect the features of the SSSI and SAC.

Hampshire Chronicle:

Construction work on the sluices at Winnall Moors' Durngate entrance

Rachel Remnant, reserves officer at Winnall Moors, said: “The trust has managed Winnall Moors through three major flood events, and we want to ensure that our expertise is respected, to safeguard the rare and special fauna and fauna that depend on the nature reserve. We also want to ensure that flood waters can be drained as quickly as possible so repairs can be made, and paths are reopened for people who love this oasis in the city.”

Flood alleviation in cities must include natural flood management schemes, reconnecting rivers with their floodplains and working with the entire catchment of the river. This is why, when the Trust took on a wider area of Winnall Moors in 2006, the river was naturalised, allowing it to flood and wet the reserve. This action recreated once-lost habitats and slowed the flow of water in the surrounding area. With flooding likely to become more frequent because of climate change, natural solutions must be considered with the same weight as hard engineering options to decrease the intensity and effects of floods.

A city council spokesman said: “The works being carried out are in line with the planning permission granted by the county council and South Downs National Park. Extensive consultation took place with Natural England, Hampshire and Isle of Wight Wildlife Trust (HIWWT) and the Environment Agency. Given the sensitive location, the environmental impacts were fully considered and the planning permission given includes a range of preventative and mitigation measures to ensure the natural environment is protected. This includes controls over how the scheme is operated, environmental monitoring, vegetation management, tree works, pond restoration and water vole refuge creation.

“The scheme has provided an opportunity to carry out biodiversity improvements at both Clausentum Fen and Nuns Walk Stream, which are planned to commence in December 2020.

“HIWWT has been included in the protocol for operating the new flood gates and we would be very happy to discuss with the trust any remaining concerns it has about the scheme.”