Brook Stream: Morphology for Mitigation

This culvert on Brook Stream, a small tributary of the River Yealm, was identified in partnership with the Environment Agency as a low cost, quick-win, site for improvement work under the South Hams River Improvement Project (SHRImP). Due to the morphology of the stream immediately downstream from the culvert, there was a significant drop-off at the exit of the culvert resulting in a very shallow flow of water through the culvert itself. Both of these features made the culvert an awkward barrier to migrating eel and trout.

Matt Healey, project officer on SHRImP, said, “After assessing the site, we decided that we could fix the problem fairly easily by carrying out some morphological work immediately downstream of the culvert; a much cheaper option than removing the culvert and reinstating the vehicle crossing.

“As luck would have it, there is a disused quarry nearby, so we were able to make use of this very local stone to create two small check weirs, raising the level of the riverbed at the outflow of the culvert and increasing the depth of water flowing through it.”

The work has improved the morphology of the stream and opened it up to migrating fish, which should help improve fish numbers in a river which currently has poor status for fish under the Water Framework Directive.