SRA Annual Report 2020-21: Natural flood management (NFM) capital grant schemes across Somerset
Schemes begun or completed in 2020-21
There can often be a time-lag between grants for schemes being approved by the SRA and work being done at sites by contractors. The first scheme in this section is a good example of an endeavour which took some time to co-ordinate. All sorts of factors can generally affect timings, such as ground conditions (too wet, too dry…) or the availability of contractors. In 2020-21, coronavirus pandemic restrictions had an additional impact.
South Somerset
Curry Rivel, Northwing Nursery, River Yeo to West Sedgemoor Drain, catchment of River Parrett. A scheme to help reduce flood risks at Curry Rivel Primary School, which is situated just below the tellingly-named Water Street. During periods of heavy rain, run-off from an area of hardstanding at Northwing Nursery flowed down to Water Street through the nursery’s gateway. Water from surrounding fields also soaked into boundary ditches which discharged into drains on Water Street. When too much of this run-off and ditch water reached the primary school, it could flood.
This scheme was therefore designed to reduce the amount of surface water reaching Water Street, and to slow the flow of water into Water Street’s drains. It was not an easy scheme to put together, because of local drainage complexities.
Its completion for the SRA is the result of careful and determined co-operation between FWAG SW, farmers, landowners, Northwing Nursery, Curry Rivel Parish Council, Curry Rivel Primary School, local people and members of Somerset County Council’s Highways Department and Flood Risk Management team.
A bunded floodwater attenuation area has been created to take excess rainfall running off from land uphill of the nursery, via a cleared ditch with new headwall and culvert, as well as run-off from the nursery’s hardstanding area, which is diverted via a cross drain and a low embankment skirting the car park.
The floodwater attenuation area has two outlets plus a spillway. The lowest outlet is a gate valve which can be opened and closed as required. The secondary outlet sits higher and discharges water at a restricted rate when the bund is almost full. If the bund is inundated, the spillway directs excess flow back to the ditch.
Work was done to a very high standard by contractors from Ilminster. The SRA used Growth Deal money from the Heart of the South West Local Enterprise Partnership.
See also the Curry Woods Conservation Trust scheme carried out as part of Trees for Water.
Misterton, Look Wood, headwaters of the River Parrett and Broad River. New woodland (0.18 hectares) has been planted close to Look Wood above Misterton, on the slopes of Knowle Hill. Look Wood sits at the start of a flow path that feeds into the headwaters of Broad River, which joins the Parrett near West Chinnock. After heavy rainfall a large amount of water runs down the road which borders Look Wood before entering a stream. Increased uptake of water from the soil through tree roots will help to slow the flow. New woodland will also help to reduce soil erosion by creating a rougher ground surface. Species chosen for planting were based on ones already present and self- seeding locally.
Queen Camel, Camel Hill Farm, River Cary catchment. During the winter, several springs have long risen out of Pepper Hill Copse and run down through a field. Large uncontrolled flows of water have eroded soil and carried silt and nutrients into a ditch, which eventually feeds into the River Cary. The aim of this scheme was to help control this runoff. A low bund and swale have been created across the slope of the field, to divert water to a new bunded attenuation area, from where it can be released slowly in a more controlled way.
Moves by the farmer to take the upper area of the field out of arable production, and grass it over, will further help to encourage infiltration and slow the flow.
Stoney Stoke, Stokeford Farm, upper catchment of River Brue. Somerset Rivers Authority part-funded the planting of 11,035 trees, 4,800 shrubs and 1,795 metres of hedgerow, which will help to reduce runoff from this heavy clay farm down to the lane that goes from Stoney Stoke to Barrow and Charlton Musgrove, the B3081 Bruton to Wincanton road and the Bruton area. Other funding came from the Environment Agency, and the Woodland Trust donated a further 1210 trees and 5805 shrubs.
Tatworth: A scheme led by Tatworth & Forton Parish Council to reduce run-off onto School Lane (home to Tatworth Primary School) from a very wet part of Jubilee Field. Jubilee Field is a 6.32 acre community amenity area designed for the use and enjoyment of local residents. Shallow swales with gently-sloping sides were created to help slow the flow of water into the watercourse that runs around part of the edge of the field, and three leaky woody dams were built in the watercourse.
Tintinhull to Montacute Road, Mill Stream, Wellhams Brook, tributary of River Parrett. This scheme began life as a highways referral, because seasonal flooding led to vehicles getting stuck in deep water and the road being closed. FWAG SW, Somerset County Council’s Highways Department, landowner James Pullen and Martock’s flood warden co-ordinator Gordon Swindells have all been involved in the improvements now made. These consist chiefly of a new 48m2 field gateway entrance designed to integrate better with the road’s drainage system and reduce silty runoff from the field, two new slipways and two new headwalls.
Somerset West and Taunton
Elworthy, Higher Vexford Farm, flow pathway at Hartrow Brake for small headwater stream for Halse Water. Two new hedge banks were created as a physical barrier to slow the flow of water. The banks were planted with native species and fenced for protection against rabbits. The hedges will help to enhance water uptake and improve infiltration. This scheme was part-funded by the SRA, with other money coming from the Environment Agency as part of the Two Valleys Natural Flood Management (NFM) project run around the Doniford and Monksilver streams near Williton in West Somerset by the Wildfowl & Wetlands Trust.
Horner, Horner Farm, 450 aspens and 450 willows planted between Horner and the popular Burrowhayes Farm Caravan and Camping site, to help reduce the amount of water reaching Horner Water in a catchment where water levels can rise quickly in response to heavy rain. Somerset Rivers Authority part-funded this scheme in support of the National Trust’s major Porlock Vale Riverlands initiative on the 12,000-acre Holnicote estate in West Somerset. The other main funders were the National Trust and the EU’s Interreg 2 Seas programme through a tie-in with Somerset’s Co-Adapt programme.
Huish Champflower, Scotts Hill Farm, upper Tone. A 55-metre hedge bank was created and planted with two staggered rows of native hedge plants. This new physical barrier slows the flow of water down a sloping field which is just above part of the upper River Tone. The hedge increases water uptake and improves infiltration.
Selworthy, National Trust’s Holnicote estate, River Aller catchment. Ponds have been created to interrupt flow pathways and store water, and a ditch has been adapted to help develop a multi-channel flow, to allow for greater infiltration of water across a longer sward of grass. These works help to reduce run-off down slopes from Selworthy to the A39 and to slow the flow of water down through the catchment of the River Aller to places such as Allerford and Bossington.
Natural flood management activities funded by Somerset Rivers Authority as part of the National Trust’s major Riverlands project in Porlock Vale are also helping to create better habitats for wildlife.
Thorne St Margaret, Rewe Farm, Upper Tone catchment. A 205-metre cross-slope hedge has been planted along a fenced boundary to reduce the risks of run-off down the slope from a neighbouring arable field.
Three sites near Triscombe, parish of West Bagborough: the Quantock Hills Area of Outstanding Natural Beauty (AONB) Service led work at three sites to slow the flow of run-off, reduce soil erosion, and trap sediment. This scheme complements earlier SRA-funded activities on the Quantocks, and helps to reduce flood risks lower down at West Bagborough.
1. At Aisholt Common, five woody dams were repaired and strengthened. Larger timber stakes were installed and larger tree limbs were placed in the dams to better slow the flow from overland run-off. These dams were originally among 15 funded by the SRA in 2017 using Growth Deal money from the Heart of the South West Local Enterprise Partnership. They were partly a reaction to three unusually intense, localised storms that raged near to West Bagborough, and over Aisholt Common and Great Wood, in May 2016. Around 1,200 tonnes of soil and gravel were washed down gullies, blocking roads and culverts which it then took weeks to clear.
2. At Black Hill, three new woody dams were installed along a ditch. Very sturdy, they make water back up behind them and so slow the flow.
3. In Rock Lane, four woody dams were created using local silver birch to reduce the flow of runoff and trap sediment.