Page 1

Wiltshire Wildlife Trust Project Overview Linking the River Avon Project

Linking the River Avon Project consists of three priority restoration projects, as identified in the River Avon Restoration Project. Please find details of the projects below: 1. Coombe Mill

Photo: Impounded reach upstream of Coombe Mill

Summary: This reach of the river Avon is in Coombe located between Long Street and Fittleton. It comprises of the downstream part of RARP reach A91a and reach A91b in its entirety. Initial observations suggest the current main channel is an artificially perched mill channel, with a uniform profile and unnatural revetments. A secondary channel (likely historic main channel) is connected via a concrete offtake. This reach is impounded by Coombe Mill which impacts fish passage. The channel shows a lack of in-stream habitat diversity and would benefit from selective tree removal/skylighting, channel narrowing and the installation of some woody habitat structures. This project aims to (1) re-apportion the flow regime between the main channel and side channel by modifying the current offtake and reducing the number of side channels to aid fish passage (2) restore reedbed habitat through the re-opening of silted up wetland features, to benefit species such as Desmoulin whorl snail (3) improve flow diversity and in-stream habitat through channel narrowing by creating berms and introducing woody material (4) bank regrading to improve floodplain connection.


Project Name: TBD (to submit as part of a wider WEG bid) Project Aim(s): • To improve fish passage for salmonids and other fish species • To create in-stream habitat for a variety of species • To enhance floodplain connectivity and to create wetland habitat to benefit species such as Desmoulin whorl snail Location: Coombe, Wiltshire

Upper Grid reference: SU 13991 50942 Central Grid reference: SU 14408 50665 Lower Grid reference: SU 14779 50421 Catchment: Hampshire Avon Waterbody: Hampshire Avon (Upper) u/s Nine Mile River confl Waterbody ID: GB108043022351 WFD status: Poor – failing to achieve GES due to fish, phosphates and overall biological water quality Protected areas: SSSI and SAC


RARP Reach: This project includes the downstream part of RARP reach A91a and reach A91b in its entirety. Length: The total channel length is approximately 1660 meters (1080m ‘main’ channel and mill leat, and 580m original channel) Potential Partners: WWT, EA, NE, MoD, Landowners Issues/Observations: • Mill channel – artificial planform, straightened, uniform channel, hard revetments, previously dredged • Connected secondary channel (likely historic main channel) via a concrete offtake weir • Hatches at Coombe mill and overspill sluice to waterwheel • Impoundment from Mill • Overwide channel • Fish passage issues • Extensive side/drainage channels – complex hydrology • Lack of in-channel habitat (woody material) • Overshading in parts Potential Solutions: • Naturalise the offtake from the main channel to the historic channel and re-apportion flow and improve fish passage • Naturalise banks across the length of the main channel and mill leat by creating shelves, riparian margins • Narrow the channel using natural material in the mill leat • Skylighting to encourage macrophyte growth • Optimise the historic channel for increased flow • Improve water levels for downstream wetland areas (habitat for Desmoulin whorl snail) • Increase in-stream variation by introducing woody material (berms, deflectors etc.) Potential Project objectives/deliverables: • To develop (or refine existing) draft designs to re-apportion the flow regime between the main channel and side channel by modifying the current offtake (including modelling) to aid fish passage • To reduce the number of offtakes from the main channel to the side channel to improve flows and water levels • To restore marginal wetland habitat to benefit species such as Desmoulin whorl snail • To develop (or refine existing) draft designs to facilitate channel narrowing and introduce habitat using woody material (tree hinging, brushwood mattresses, deflectors) • To regrade riverbanks to improve floodplain connectivity


2. Gated Crossing

Photo: An example of skylighting and channel narrowing through introducing woody habitat features

Summary: This reach of the river Avon is located between Netheravon and Figheldean and makes up part of RARP reach A95. Initial observations suggest the channel shows a lack of in-stream habitat diversity and would benefit from selective tree removal/skylighting, channel narrowing and the installation of some woody habitat structures. The channel is overwide and deep at points and would benefit from bed raising via gravel introduction. This project aims to achieve (1) channel narrowing by creating berms and introducing woody habitat (2) selective removal of bankside trees to open up the channel and encourage macrophyte growth (3) gravel introduction to raise the bed and provide suitable spawning substrate for salmonid species.


Project Name: TBD (to submit as part of a wider WEG bid) Project Aim(s): • To create in-stream habitat for a variety of species • To provide suitable spawning habitat for salmonids and other fish species Location: Netheravon, Wiltshire

Upper Grid reference: SU 14889 48240 Central Grid reference: SU 15130 48064 Lower Grid reference: SU 15405 47899 Catchment: Hampshire Avon Waterbody: Hampshire Avon (Upper) u/s Nine Mile River confl Waterbody ID: GB108043022351 WFD status: Poor – failing to achieve GES due to fish, phosphates and overall biological water quality Protected areas: SSSI and SAC RARP Reach: This project makes up approximately 600m of RARP reach A_95


Length: The total channel length is approximately 600m meters Potential Partners: WWT, EA, NE, Landowners Issues/Observations: • Overwide deep channel • Lack of suitable spawning habitat • Lack of in-channel habitat (woody material) • Overshading in parts Potential Solutions: • Increase in-stream variation by introducing woody material (berms, deflectors etc.) • Skylighting to encourage macrophyte growth • Gravel introduction Potential Project objectives/deliverables: • To develop (or refine existing) draft designs to facilitate channel narrowing and introduce habitat using woody material (tree hinging, brushwood mattresses, deflectors) • To selectively remove bankside trees to open up the channel and encourage macrophyte growth • To introduce gravel to raise the bed and provide suitable spawning substrate for salmonid species


3. Littlecot Farm

Photo: An example of a floodplain reconnection project upstream at Tank Crossing A

Summary: This reach of the river Avon is located between East Chisenbury and Enford and makes up part of RARP reach A18. Initial observations suggest the channel shows a lack of in-stream habitat diversity and would benefit from selective tree removal/skylighting, channel narrowing and the installation of some woody habitat structures. There is also scope to reconnect the channel with the floodplain to restore wetland habitat and increase floodplain storage capacity. This project aims to achieve (1) channel narrowing by creating berms and introducing woody habitat (2) selective removal of bankside trees to open up the channel and encourage macrophyte growth (3) floodplain reconnection through bank regrading and scrape creation.


Project Name: TBD (to submit as part of a wider WEG bid) Project Aim(s): • To create in-stream habitat for a variety of species • To provide suitable spawning habitat for salmonids and other fish species • To reconnect/create floodplain habitat • To reduce diffuse pollution by reducing grazing pressure Location: Littlecott, Wiltshire

Upper Grid reference: SU 13900 51855 Central Grid reference: SU 14055 51889 Lower Grid reference: SU 14196 51855 Catchment: Hampshire Avon Waterbody: Hampshire Avon (Upper) u/s Nine Mile River confl Waterbody ID: GB108043022351 WFD status: Poor – failing to achieve GES due to fish, phosphates and overall biological water quality Protected areas: SSSI and SAC


RARP Reach: This project makes up approximately 320m of RARP reach A_18 Length: The total channel length is approximately 320m meters Potential Partners: WWT, EA, NE, Landowners Issues/Observations: • Overwide deep channel • Lack of suitable spawning habitat • Lack of in-channel habitat (woody material) • Overshading in parts • Floodplain disconnection Potential Solutions: • Increase in-stream variation by introducing woody material (berms, deflectors etc.) • Skylighting to encourage macrophyte growth • Floodplain reconnection Potential Project objectives/deliverables: • To develop designs to facilitate channel narrowing and introduce habitat using woody material (tree hinging, brushwood mattresses, deflectors) • To selectively remove bankside trees to open up the channel and encourage macrophyte growth • To create floodplain wetland habitat to benefit species such as Desmoulin whorl snail

Profile for HACP

Linking the avon restoration project  

Linking the avon restoration project  

Profile for hacp0
Advertisement