Case study:Rottal Burn

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Location: 56° 48' 37", -3° 2' 2"
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Project overview

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Status Complete
Project web site http://www.erft.org.uk/index.php/articles/articles/271-restoration-of-the-rottal-burn-glen-clova
Themes Fisheries, Habitat and biodiversity
Country Scotland
Main contact forename Dr Marshall
Main contact surname Halliday
Main contact user ID
Contact organisation Esk Rivers and Fisheries Trust
Contact organisation web site http://www.erft.org.uk/
Partner organisations
Parent multi-site project
This is a parent project
encompassing the following
projects
No
Restoration of the historic meandering channel

Project summary

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The reach of the Rottal burn between Rottal Lodge and its confluence with the South Esk has historically been realigned and straightened since the 1830’s. In 2003, just prior to the Water Framework Directive coming into force, the stretch was dredged out destroying the existing habitat. The works carried out in 2012 aimed to restore natural river processes and in stream and riparian habitat, specifically for Atlantic salmon and freshwater pearl mussel alongside other fish species. It is relevant to note that the freshwater pearl mussel is dependent on juvenile salmon populations for the completion of its life cycle.

Objectives of the project included: • Restoration of the canalised water course as far as possible to its natural course (to be extended from 650m to 1,100m) • Reconnection of the Rottal Burn with its flood plain • Creation of a diverse riparian and aquatic habitat including the incorporation of the existing wetland habitat into the final restoration design • Reduction in the unnaturally high sediment loading during high flow events which is then deposited in the lower reaches • A return to a more natural flow regime • Attenuation of flood peaks • Visual enhancement of the area • Restoration of sustainable, functional populations of multi-sea-winter salmon and trout and of freshwater pearl mussels • The possibility of transferring freshwater pearl mussels into the burn will be investigated • Development a demonstration site available for future research • Provision of restoration experience which would be transferable to other similar situations within the catchment

Construction works were designed to create the restored channel without any import or export of materials, by using existing gravel embankments to provide any material needed. Large woody debris (trees with rootballs) which were sourced from the local estate, were used to reinforce possible areas of adjustment. A two-phase construction programme was used; Firstly the new channel was constructed and vegetation growth allowed to take hold. Following this flow was diverted into the new channel. Challenges at the site included the remote location, adverse weather conditions and the presence of overhead services. A number of sediment bar features have already formed, significantly improving the habitat, which is confirmed by the presence of salmon spawning in the new channel.

The primary funder for the project was the Scottish Environment Protection Agency (SEPA). If you are interested in applying for funding to deliver other projects in Scotland, visit SEPA's Water Environment Fund webpage (http://www.sepa.org.uk/water/water_environment_fund.aspx).

Monitoring surveys and results

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Lessons learnt

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Image gallery


Prior to restoration - channel had been straightened
After restoration
Taken pre-restoration - location of the newly created channel
pre-restoration
immediately post-restoration
post-restoration
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Catchment and subcatchment

Catchment

River basin district Sout Esk
River basin South Esk

Subcatchment

River name South Esk
Area category 100 - 1000 km²
Area (km2) 564 km²
56,400 ha
Maximum altitude category 200 - 500 m
Maximum altitude (m)
Dominant geology Siliceous
Ecoregion Great Britain
Dominant land cover Grassland, Woodland
Waterbody ID



Other case studies in this subcatchment: South Esk restoration



Site

Name Rottal Burn
WFD water body codes
WFD (national) typology
WFD water body name
Pre-project morphology Straightened, dredged (to remove gravels)
Reference morphology Actively meandering (historic channel identified)
Desired post project morphology
Heavily modified water body No
National/international site designation EU - Special Area of Conservation
Local/regional site designations
Protected species present Yes
Invasive species present No
Species of interest Atlantic salmon, The freshwater pearl mussel
Dominant hydrology
Dominant substrate Gravel
River corridor land use Rough unimproved grassland/pasture
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) 1100
1,100 m
1.1 km
110,000 cm
Project started 2012
Works started 2012/04/01
Works completed 2012/08/01
Project completed
Total cost category 100 - 500 k€
Total cost (k€)
Benefit to cost ratio
Funding sources Scottish Environment Protection Agency

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 Historic straighteneing
Hydromorphology Quantity & dynamics of flow, Channel pattern/planform
Biology Fish
Physico-chemical
Other reasons for the project Improvement of atlantic salmon and freshwater pearl muscle habitat


Measures

Structural measures
Bank/bed modifications Adding sinuosity, Bank re-grading, Decrease sedimentation, Riverbed widening
Floodplain / River corridor Floodplain reconnection, Removal of embankments
Planform / Channel pattern Adding sinuosity
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
Channel pattern/planform No Yes No No No

Biological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative
Fish No Yes No No No

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



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Supplementary Information

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