Case study:River Ouse at Sharpsbridge Rock Ramp Fish Easement Project

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Location: 50° 58' 5", 0° 2' 57"
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Project overview

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Status Complete
Project web site
Themes Fisheries, Flood risk management, Habitat and biodiversity, Hydromorphology, Water quality
Country England
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

Case_study:The Middle Ouse Restoration of Physical Habitats (MORPH)

This is a parent project
encompassing the following
projects
No
Sharpsbridge rock ramp scheme post works © Royal HaskoningDHV

Project summary

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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.

Preparation

  • 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.

Works

  • 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.

Post-construction works

  • Works to rectify the site compound were undertaken. Signs were erected to divert canoeists around the eastern channel.

Monitoring surveys and results

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Lessons learnt

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  • 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.


Image gallery


Sharpsbridge under construction (1) © Royal HaskoningDHV
Sharpsbridge under construction (2) © Royal HaskoningDHV
Sharpsbridge under construction (3) © Royal HaskoningDHV
Looking downstream post works © Royal HaskoningDHV
Looking upstream post works © Royal HaskoningDHV
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Catchment and subcatchment

Catchment

River basin district South East
River basin Adur and Ouse

Subcatchment

River name Ouse from Cockhaise Brook confluence to Spithurst
Area category 100 - 1000 km²
Area (km2)
Maximum altitude category 100 - 200 m
Maximum altitude (m) 161
161 m
0.161 km
16,100 cm
Dominant geology Siliceous
Ecoregion Great Britain
Dominant land cover Improved grassland
Waterbody ID GB107041012710



Other case studies in this subcatchment: Spring Meadow Meander Restoration


Site

Name
WFD water body codes GB107041012710
WFD (national) typology
WFD water body name Ouse from Cockhaise Brook confluence to Spithurst
Pre-project morphology
Reference morphology
Desired post project morphology
Heavily modified water body No
National/international site designation
Local/regional site designations
Protected species present No
Invasive species present No
Species of interest
Dominant hydrology
Dominant substrate
River corridor land use
Average bankfull channel width category
Average bankfull channel width (m)
Average bankfull channel depth category
Average bankfull channel depth (m)
Mean discharge category
Mean annual discharge (m3/s)
Average channel gradient category
Average channel gradient
Average unit stream power (W/m2)


Project background

Reach length directly affected (m)
Project started 2009/01/01
Works started
Works completed
Project completed 2012/12/31
Total cost category
Total cost (k€)
Benefit to cost ratio
Funding sources

Cost for project phases

Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname
Investigation and design Royal HaskoningDHV
Stakeholder engagement and communication Ouse and Adur Rivers Trust
Works and works supervision Environment Agency and C A Blackwell
Post-project management and maintenance
Monitoring



Reasons for river restoration

Mitigation of a pressure Flood risk management, Impoundments (not hydropower)
Hydromorphology Continuity for organisms, Continuity of sediment transport, Quantity & dynamics of flow
Biology Fish
Physico-chemical Oxygen balance
Other reasons for the project


Measures

Structural measures
Bank/bed modifications Rock ramp construction
Floodplain / River corridor
Planform / Channel pattern
Other
Non-structural measures
Management interventions
Social measures (incl. engagement)
Other


Monitoring

Hydromorphological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Biological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Physico-chemical quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Any other monitoring, e.g. social, economic

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative


Monitoring documents



Additional documents and videos


Additional links and references

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Supplementary Information

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