Great Race Eddies and Turbulence

Lead Research Organisation: Scottish Association For Marine Science
Department Name: Dunstaffnage Marine Laboratory

Abstract

Between the islands of Jura and Scarba in western Scotland lies the Gulf of Corryvreckan, famous for its intense tidal flow and whirlpool. Less well known is the 'Great Race', the spectacular, narrow extension of that flow to the west. On each tidal cycle, water is injected into the open water of the Firth of Lorn at a rate comparable to the discharge of the Amazon. Not surprisingly, this flow has a profound impact on the region that receives it. Simulations suggest that a pair of eddies forms at the head of the Race during each tidal cycle, a clockwise eddy to the north and an anticlockwise eddy to the south. These eddies persist for several tidal cycles as they evolve, interact and are displaced by newly-formed eddies, so the Great Race is effectively a stirring rod for the Firth of Lorn. We plan to use this remarkable natural laboratory to make advances in the understanding of eddies, turbulence and mixing in highly-tidal environments which will feed directly into an improved ability to simulate such environments numerically. This project will use an array of cutting-edge technologies and instrumentation. We will release clusters of flow-tracking surface drifters into the Great Race and its eddies, developing techniques for rapidly monitoring them via a mobile phone network. An Autonomous Underwater Vehicle (AUV) will propel itself beneath the Great Race, measuring its turbulent structure on the smallest scales, while ship-based surveys will paint out the wider picture from above. Each of these techniques will contribute to our building understanding. Once the essential nature and behaviour of the Great Race have been determined the key task will be to understand how energy is distributed among eddies of different scales and how this energy 'cascades' between scales with increasing distance from the eddy source. It is these features that a successful numerical model will represent accurately. Model development is an integral part of this project. The knowledge gained from the field program will feed directly into evaluating and improving models and their treatment of motions that are too small to be directly represented. The initial focus will be on a local-scale model of the Great Race and its surroundings. A studentship will look at incorporating knowledge gained at this scale into wider area models, potentially extending to the entire west coast of Scotland. A west coast model that is skilful at the important small scales but also represents their interconnection at larger scales will allow better-informed management of fisheries, renewable energy development and more.

Publications

10 25 50
 
Description This project has revealed a wealth of fluid dynamical features related to strong tidal flows, including generated eddies, and flow instabilities. These are of interest to the emerging tidal energy industry and provide a demanding test case for hydrodynamic models of tidal flow. The drifter technology developed has been used under subsequent funding and is under ongoing develoment as a tool for characterisation of tidal environments as well as other coastal management applications. Collaborations that were not planned at the outset, related to the ecological role of tidal systems, have been very fruitful, clarifying the way in which cetaceans and seabirds use these sites as a feeding resource. In particular, harbour porpoises and razorbills have both been shown to be attracted to turbulent environments and to structure their movements around the tidal cycle.
Exploitation Route The main avenues for taking forward the findings of this project are within the marine energy community, informing model development and validation for tidal power sites, as well as understanding the variability of such systems, with implications for the design of turbines and arrays of turbines. Within the ecological community, the role of energetic tidal sites in wider shelf ecology is useful for management purposes, and for the understanding of connectivity, for instance of the developing networks of Marine Protected Areas.
Sectors Energy

Environment

 
Description The findings of this grant have been widely communicated outside of academia, via television, talks and activities in local schools and talks to community groups. The drifter technology has been used beyond the project end in collaboration with an industry partner, and further development and exploitation is planned.
Sector Aerospace, Defence and Marine,Education
Impact Types Cultural

 
Description Scallop fishery closure in the Firth of Lorn
Geographic Reach National 
Policy Influence Type Contribution to a national consultation/review
Impact Participation in Marine Scotland workshop (Sept 2012) looking into the scientific understanding of the impacts of scallop dredging in the Firth of Lorn Special Area of Conservation. This fishery is currently closed pending scientific analysis of its impact on habitats. Outcomes of this analysis will directly inform forthcoming government decisions concerning the closure.
 
Description Technology Strategy Board: Environmental Data
Amount £22,860 (GBP)
Funding ID Application 37218-270305 
Organisation Innovate UK 
Sector Public
Country United Kingdom
Start 03/2014 
End 04/2015
 
Description Collaboration with RSPB FAME project 
Organisation Royal Society for the Protection of Birds (RSPB)
Country United Kingdom 
Sector Charity/Non Profit 
PI Contribution As part of the EU-funded FAME project, the RSPB is conducting GPS tracking of seabirds from their Colonsay nest sites. Many of these birds feed in the Great Race, so the RSPB/FAME and Great Race datasets show considerable overlap. A fruitful collaboration has been established with Ellie Owen (RSPB) looking into the links between tidal physics and patterns of seabird distribution.
Start Year 2012
 
Description BBC Landward programme: Television interview and demonstration of drifter techniques used in Great Race study 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Media (as a channel to the public)
Results and Impact Programme was aired on BBC2 in Scotland and nationally available via BBC iplayer.

Frequent requests for information on the Gulf of Corryvreckan, whirlpools and tidal dynamics, and to give public talks, visit schools etc.
Year(s) Of Engagement Activity 2014
URL http://www.bbc.co.uk/programmes/b0439tqh
 
Description Craignish Primary School, activity for P5-P7 pupils 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Talk and activities sparked enthusiastic response and questions from pupils.

Frequent requests for information on the Gulf of Corryvreckan, whirlpools and tidal dynamics, and to give public talks, visit schools etc.
Year(s) Of Engagement Activity 2014
 
Description Discovery Channel UK Deadly Dilemmas programme: Television interview concerning whirlpool dynamics 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Popular science panel programme. Interviewed as scientific expert on whirlpool dynamics. Broadcast in UK and internationally.

Frequent requests for information on the Gulf of Corryvreckan, whirlpools and tidal dynamics, and to give public talks, visit schools etc.
Year(s) Of Engagement Activity 2013
URL http://www.discoveryuk.com/web/deadly-dilemmas/
 
Description Public talk as part of Oban Festival of the Sea: Downstream of the Corryvreckan 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Talk sparked interested questioning and discussion.

Frequent requests for information on the Gulf of Corryvreckan, whirlpools and tidal dynamics, and to give public talks, visit schools etc.
Year(s) Of Engagement Activity 2012
URL http://www.obanseafestival.org/events/downstream-of-the-corryvreckan-tracking-currents-birds-and-por...
 
Description Public talk at Ocean Explorer Centre, Oban: Downstream of the Corryvreckan 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Talk sparked interested questioning and discussion.

Frequent requests for public talks about the Gulf of Corryvreckan.
Year(s) Of Engagement Activity 2014
 
Description Public talk to Craignish Boat Club: Submarine geomorphology and tidal flows in the Firth of Lorn' 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Talk sparked interested questioning and discussion.

Frequent requests for information on the Gulf of Corryvreckan, whirlpools and tidal dynamics, and to give public talks, visit schools etc.
Year(s) Of Engagement Activity 2014
 
Description Public talk to Scottish Wildlife Trust local group 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Talk sparked interested questions and discussion.

Frequent requests for information on the Gulf of Corryvreckan, whirlpools and tidal dynamics, and to give public talks, visit schools etc.
Year(s) Of Engagement Activity 2012