SRA Annual Report 2022-23: River Sheppey catchment action plan
After the flooding of 26 homes and of roads including the A371 in Croscombe and Shepton Mallet in October 2020, Somerset Rivers Authority gave Mendip District Council funding for a major study.
Its purpose: to understand more about the causes of local flooding, so that plans could be devised for reducing flood risks and making places more resilient to flooding.
Work began in 2021, continued throughout 2022-23 and is now nearly complete.
Investigations were led by Mendip’s flood risk consultants Calm Engineering, working with Somerset County Council, the Environment Agency and Wessex Water, Carroll Environmental, Ghyston Engineering, Hydro-Morph, FWAG SW and the Wild Trout Trust.
Together they studied the sub-catchments of Croscombe and Shepton Mallet, including Charlton, Bowlish and Darshill along the River Sheppey and other places such as Ham, Downside and Bodden. Titwell Wood stream, Coombe Lane Brook, Collett Park stream, Bullimore Brook and Doulting Stream have been assessed, along with springs that emerge to the east of Shepton Mallet including St Aldhelm’s well, an ancient holy well reputed never to run dry.
Other notable local features include the swallow hole along Thrupe Lane above Croscombe, which takes water from a small stream into a cave system about 120 metres deep. This water reappears in Wells. It is a common feature of investigations into water in Somerset that the closer people look, the more strange and complex worlds open up!
Project teams have reviewed large amounts of existing information about (for example) previous flooding incidents, carried out additional investigations (two new CCTV surveys in 2022), studied flood risks and how to mitigate them, and looked at how local people could improve local resilience. Text continues below photographs.
At times the project team worked in tandem with the SRA’s community engagement officers, who were supporting the Croscombe Flood Committee. In April 2022, this Committee became a working group which now provides advice and makes recommendations to the parish council – and which also has equipment and materials funded by the SRA through Somerset Prepared.
In March 2023, two project team members gave a presentation to Shepton Mallet Town Council in which they picked out numerous issues, grouped according to SRA workstreams.
Workstream 1 issues
- historic modification of the river channel
- condition of culverts
- riverbed level changes
- channel obstructions
Workstream 2 issues
- land use in upper catchment, e.g. winter grazing, maize-growing, runoff from farm tracks
Workstream 3 issues
- an almost complete lack of sustainable urban drainage systems, with large swaths of impermeable paved areas in Shepton Mallet
- need for additional guidance and changes in local policies
Workstream 4 issues
- capacity and condition of parts of the drainage network
Workstream 5 issues
- accessibility of flood information
- community awareness of flooding and local resilience measures
- lack of resources to respond to flood incidents
- need for additional property level resilience measures
A final report is now being prepared. It is likely to include around 120 very specific recommendations, right down to individual culverts.
In some simpler cases, SRA partners such as the Environment Agency and Somerset Council’s Highways Department have already begun to make improvements.