Case study:River Ouse at Sharpsbridge Rock Ramp Fish Easement Project
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- 1 Project overview
- 2 Image gallery
- 3 Catchment and subcatchment
- 4 Site
- 5 Project background
- 6 Reasons for river restoration
- 7 Measures
- 8 Monitoring
- 9 Additional documents and videos
- 10 Additional links and references
- 11 Supplementary Information
|Project web site|
|Themes||Fisheries, Flood risk management, Habitat and biodiversity, Hydromorphology, Water quality|
|Main contact forename||Ian|
|Main contact surname||Dennis|
|Main contact user ID|
|Contact organisation||Royal HaskoningDHV|
|Contact organisation web site||http://www.royalhaskoningdhv.com/|
|Partner organisations||Environment Agency, Ouse and Adur Rivers Trust, C A Blackwell|
|Parent multi-site project|
| This is a parent project
encompassing the following
Sharpsbridge is a road bridge, with two culverts that carry flow under the road and an island in the channel downstream. The footings of the road bridge are formed of a solid concrete slab which acts as a weir, backing up flow. The height of the drop between the concrete slab and the water level was causing a barrier to fish passage. Previous work was undertaken to place rubble rock at the downstream extent of the concrete slab to enable fish migration; however, this began to function as an additional barrier. The aim of this project was to improve fish passage in one of the culverts, to allow free movement of fish upstream. In order to eliminate the barrier to fish passage, the water levels in the downstream weir pool were raised by the addition of a rock ramp structure.
- The western channel was blocked using temporary dams and pumps to move water through the eastern side of the bridge. During high water flows, the dams were periodically removed to prevent flooding.
- The existing rubble rock weir was removed.
- A 4.5 m wide rock ramp was constructed in-situ, using granular fill and geotextile at the base, concrete at the upstream end, and rock armour forming the surface of the ramp.
- Kentish ragstone (a hard limestone) was used for the main perturbation boulders because of its durability.
- Rocks were positioned approximately equidistant, with increasing height of rocks upstream, to ensure a smooth gradient of flow over the former head drop.
- Works to rectify the site compound were undertaken. Signs were erected to divert canoeists around the eastern channel.
Monitoring surveys and results
- The project team was able to draw upon experience from Belgium and The Netherlands to help determine the best layout of the large boulders on the ramp.
- Carbon calculators were used, and were able to highlight the transport of materials as a high carbon cost, leading to the successful sourcing of local materials to construct the ramp.
Catchment and subcatchment
Select a catchment/subcatchment
Other case studies in this subcatchment: Spring Meadow Meander Restoration
Cost for project phases
Reasons for river restoration
Hydromorphological quality elements
Biological quality elements
Physico-chemical quality elements
Additional documents and videos