Funded by Natural England’s Countryside Stewardship scheme and working with Wessex Rivers Trust and the Environment Agency, Hampshire and Isle of Wight Wildlife Trust has developed a capital works plan to re-naturalise the Eastern Yar floodplain to improve degraded and damaged wetland habitats and promote biodiversity.
Currently, the main river channel is disconnected from the floodplain due to historic dredging. As a result, during peak flow events (such as following prolonged heavy rainfall) in-channel water struggles to spread laterally onto surrounding land which would be the natural floodplain, and instead is forced to travel at high velocity in the main channel which can cause flash flooding at pinch points such as culverts underneath road bridges.
The Trust owns about 300 acres along the Eastern Yar floodplain in a series of five interconnecting nature reserves, from Newchurch down through to Morton Marsh. This land mainly consists of wet grasslands, fen and wet woodland, partially comprising Alverstone Marshes Site of Special Scientific Interest (SSSI). A large portion of the grassland has suffered biodiversity loss due to drainage which has allowed scrub encroachment and loss of species dependent on ephemeral or seasonal waterlogging.
In its natural state a floodplain system is a dynamic landscape, and water is abundant in the landscape in multiple channels, pools and sometimes large areas of water. This dynamism and wetness provide diversity and structure for a vast array of flora and fauna and is something we look forward to bringing back to this landscape.
The work itself will involve two main components - removal of scrub and trees and re-profiling of watercourses.
Phase 1 - removal of scrub and trees
In August 2024 we will be reducing the scrub cover on the SSSI fen habitat at Lower Knighton Moors Nature Reserve. This will involve:
- Cutting and burning willow scrub in the centre of the site to allow space for the herb rich fen community to recover in areas where tree cover has shaded it out
- Removing some of large poplar trees near to the public right of way
- Reducing the height of some of the poplar trees to reduce shading
- Ring-barking some poplar trees to create standing dead wood habitat to benefit fungi, invertebrates, bats and cavity nesting birds.
During this phase of works the right of way may be closed for short periods of time (up to 15 mins) whilst limbs of trees are removed. Trust staff will be on site to ensure safe management of this. All trees and work sites will be surveyed for nesting birds and roosting bats immediately prior to work commencing. Project work will cease or relocate as appropriate based on the findings of the surveys. Works will then move on to Newchurch Moors Nature Reserve to reduce the willow scrub on the fen and wet grassland habitats south of the cycle track.
Phase 2 - re-profiling of watercourses
In September 2024 works will begin at Newchurch Moors, moving downstream through Alverstone Mead and onto Sandown Meadows to re-profile sections of the main river channel and surrounding land to create and restore wetland habitats.
Works will consist of:
- Removing small sections of the raised riverbanks to allow the main channel to connect with and utilise the flood storage capacity of the floodplain.
- At Alverstone Mead and Sandown Meadows, there will be re-profiling and shallow excavations on existing drainage ditches to create wetland features such as ponds and scrapes which will create further flood storage capacity and help to re-wet drained areas and encourage the return of wetland flora and fauna.
- Creating bunds from some of the spoil generated from excavations to protect low lying areas of the cycle track at Newchurch and Golf Links Road at Sandown Meadows.
- Replacing a weir at Alverstone Mead on the existing drainage network. This weir no longer functions well to control the water levels on site. This structure will be replaced as part of the work and the resulting infrastructure will be more appropriate for fish and eel passage. It will also allow greater control of on-site water levels to assist with site management such as allowing grazing and/or hay cutting on the wet meadows.
- Rerouting public footpath SS38 at Sandown Meadows. This river restoration work will mean the permanent closure of the permissive right of way through the site along the river as this area will become wetter. The current route of SS38 crosses Sandown Meadows north to south, linking Lower Road with Perowne Way and is currently impassible through much of the year due to flooding and the wet ground. We have agreed with the Isle of Wight Council that the path will be diverted, providing a more accessible route around the site’s perimeter and to ensure that a route still remains accessible in the locality. This route is drier and already well used by many people.
- All project areas have been, and will continue to be, surveyed for water voles, and work will cease or be relocated if they are found.
This project will benefit both wildlife and people. We look forward to sharing project updates and we will be documenting the project so we can share the story once complete.
If you have any further enquires or questions please do not hesitate to contact Emma Hunt, Isle of Wight Reserves Officer:
Emma.Hunt@hiwwt.org.uk
07741 312892