Case study:River Dee

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Location: 52° 57' 3", -3° 0' 34"
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Project overview

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Status Complete
Project web site http://www.riverdee.org.uk/welcome.asp
Themes Economic aspects, Habitat and biodiversity, Hydromorphology, Land use management - agriculture, Monitoring, Spatial planning
Country England
Main contact forename Nick
Main contact surname Elbourne
Main contact user ID User:NickRRC
Contact organisation River Restoration Centre
Contact organisation web site http://www.therrc.co.uk
Partner organisations River Dee Trust
Parent multi-site project
This is a parent project
encompassing the following
projects
No
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Project summary

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Obstructions to fish migration on the Dee:

Since 2007, the Dee DSFB and Trust have eased or removed 27 manmade obstructions to fish migration from the river Dee's tributaries.

the aim is simple: To allow fish to gain access to their natural spawning grounds.

These manmade obstructions include weirs, bridges, vehicle fords and culverts. Some are completely impassable to fish, others are impassable in low flows; the latter can delay migration and have a knock-on effect of making fish more vulnerable to predators and stress.

In 2007 we assessed all the known manmade obstructions to prioritise them for easement or removal. For example, removing an obstruction that is on a tributary with poor habitat for salmon, or that is located close to the headwater source, will offer a lot less potential for increasing fish production than removing an obstruction that is low down on a prime-quality tributary.

The physical work of tackling the obstructions is often supported by obtaining external funding, particularly from SEPA's Water Environment Fund and from the EU LIFE fund. The physical works are completed by contractors or in many cases by our staff.

In 2014, the largest manmade obstruction was eased by installing a fish pass to the face of the Culter dam and two weirs further upstream in the Culter tributary were eased

Monitoring surveys and results

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On 3rd October 2014 the first salmon ascended the Culter Dam in over 250 years, thanks to a fish pass we installed on the dam just days earlier funded entirely by businessmen Martin Gilbert and Stewart Spence. This dam, at Peterculter, is the largest man-made obstruction on the River Dee.

  • 2014 Season: Numbers up the fish pass to date (June 2015): 43 Salmon 69 Sea trout

Why install a fish pass on the Culter?

The fish pass has opened up 76 miles of habitat in the previously inaccessible Culter burn for migratory salmon and sea trout to re-establish natural populations in.

Only the lowest one mile of burn is below the dam and so accessible to salmon and sea trout. The spawning and rearing habitat in this part of the burn is fully utilised, resulting in high juvenile fish densities. High juvenile fish densities mean lots of competition and higher mortality rates. Creating more rearing habitat for juveniles will result in lower mortality rates and so higher fish production.

Once habitat restoration work is completed in the Culter catchment we expect to see an additional 1,500 salmon returning to the Dee each year.

These salmon may be available to the catch and release rod fishery as far up river as Banchory, as our radio tracking studies show how fish may wander up to 20km upstream from where they eventually spawn.


Monitoring Fish Pass Success

A Vaki fish counter is installed at the top of the fish pass to record how many fish are using the pass to ascend the dam. The counter records the length of each fish. We assume that all fish longer than 50cm are salmon, fish between 30 and 50cm length are sea trout and fish less than 30cm are brown trout. In practice, there is some size overlap, particularly between small salmon and large sea trout. Our scale data show we would expect 6% error in these classifications.

Lessons learnt

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Catchment and subcatchment

Catchment

River basin district Dee
River basin Middle Dee

Subcatchment

River name Dee - Chester Weir to Ceiriog
Area category 1000 - 10000 km²
Area (km2)
Maximum altitude category 100 - 200 m
Maximum altitude (m) 136
136 m
0.136 km
13,600 cm
Dominant geology Calcareous
Ecoregion Great Britain
Dominant land cover Improved grassland
Waterbody ID GB111067057080



Other case studies in this subcatchment: QUERCUS Dee


Site

Name Dee Restoration
WFD water body codes GB111067057080
WFD (national) typology
WFD water body name Dee - Chester Weir to Ceiriog
Pre-project morphology Single channel
Reference morphology Sinuous, Pool-riffle
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 Quick run-off, Groundwater
Dominant substrate Gravel, Cobble
River corridor land use Extensive agriculture
Average bankfull channel width category 5 - 10 m
Average bankfull channel width (m)
Average bankfull channel depth category 2 - 5 m
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
Works started
Works completed
Project completed
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
Stakeholder engagement and communication
Works and works supervision
Post-project management and maintenance
Monitoring



Reasons for river restoration

Mitigation of a pressure Abstraction, Reservoir impoundment
Hydromorphology Channel pattern/planform, Quantity & dynamics of flow, Flow velocities, Continuity for organisms
Biology Fish: Species composition, Fish: Abundance
Physico-chemical
Other reasons for the project Fisheries


Measures

Structural measures
Bank/bed modifications Planting, Introduction of spawning gravels, Regrading
Floodplain / River corridor
Planform / Channel pattern Adding sinuosity
Other
Non-structural measures
Management interventions
Social measures (incl. engagement)
Other Information provision, Consultation, Participation in design


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
Fish: Species composition Yes Yes Yes Improvement
Fish: Abundance Yes Yes Yes Improvement

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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