Dynamics of Rip currents and Implications for Beach Safety (DRIBS)
Lead Research Organisation:
Plymouth University
Department Name: Sch of Marine Science & Engineering
Abstract
Rip currents are strong and narrow currents in the surf zone that extend seaward of the breaking waves and return water seaward that has been transported into the surf zone by breaking waves. Rip currents are found on high-wave beaches with bars with the rips cutting through the bars in the form of distinct channels. Rip currents can be very strong with flow velocities of 1-2 m/s and are the main hazard to surf zone water users. According to lifeguard records, over 68% of incidents ('rescues') on UK beaches can be attributed to rip currents. A similar percentage is reported from Australia and the USA and, in Florida alone, over 100 people drown each year due to rip currents. Rip currents not only transport people out to sea, but also other material, such as sediment, plankton, nutrients and pollutants. Rip currents are therefore also important for beach erosion and surf zone water quality. The importance of rip currents for beach safety is well recognised by coastal scientists and lifeguards, but we do not fully understand what controls their flow strength and pattern. Our understanding is particularly poor for rip currents on beaches with a large tide range. On some beaches, strong rips cut through bars and sweep swimmers out to sea, whereas on other beaches the rip current develops a large circulating eddy within the surf zone. The risks posed to surf zone water users, and the potential for beach erosion and surf zone flushing, will depend strongly on the type of rip circulation. We believe that rip currents are strongest when all wave breaking occurs on the bar and none of the waves break in the rip channel. We hypothesise that under such conditions the rip generation mechanism is maximised and this depends on wave conditions, tide and bar morphology. All three factors vary over time and even subtle changes in any of them may have significant repercussions for the rip circulation. The overall aim of this project, Dynamics of Rip currents and Implications for Beach Safety (DRIBS), is to test this idea by measuring rip currents under a variety of wave, tide and beach conditions, and complementing the data analysis with computer modelling. We will conduct a 6-week field campaign on two high-wave, large-tidal beaches along the north Cornish coast where mass rescue events of upwards of 150 people per beach have required simultaneous rescue due to rip currents. During each of these campaigns, we will install several instruments in the surf zone that will measure waves, tides and rip currents at fixed locations. In addition, we will use a large number of specialist drifters that measure the complete rip current pattern. The drifters will be released in the surf zone and will move according to the nearshore current pattern. Their location will be continuously monitored (using GPS) and the data from the drifters will provide useful information not only on the strength of the rip current, but also on the type of flow pattern. The drifters are designed to behave like human beings and their movement therefore mimics that of passive bathers. The information collected during the field campaigns will be used to develop a computer model that is able to predict the rip flow pattern for any given wave, tide and beach condition. We will then use this model to develop tools that can be used by lifeguards to determine the rip current risk and develop strategies to deal with this risk. This research project involves the Royal National Lifeboat Institution (RNLI) as a Partner and the RNLI will be involved during all stages of the work. The partnership will be mutually beneficial: the RNLI will help us with the field measurements by making available their dedicated staff and facilities, and we will pass on the research findings to the RNLI via workshops, lectures, leaflets and other types of publications. More importantly, the research findings will be incorporated into the RNLI's risk assessment procedures and resource management tools.
Publications
Brander, R; Scott, T.
(2016)
The Science of Beach Lifeguarding: Principles and Practice
Woodward, E. M.
(2013)
Analysis of Rip Current Incidents and Victim Demographics in the UK
Van Dongeren, A.
(2013)
Rip current prediction through model-data assimilation on two distinct beaches
Miles J
(2014)
Observations of bedforms on a dissipative macrotidal beach
in Ocean Dynamics
Pitman S
(2016)
Wave breaking patterns control rip current flow regimes and surfzone retention
in Marine Geology
Scott T
(2011)
Morphodynamic characteristics and classification of beaches in England and Wales
in Marine Geology
Scott T
(2016)
The extreme 2013/2014 winter storms: Beach recovery along the southwest coast of England
in Marine Geology
MacMahan J
(2010)
Mean Lagrangian flow behavior on an open coast rip-channeled beach: A new perspective
in Marine Geology
Miles J
(2014)
Megaripple dynamics on a dissipative sandy beach
in Journal of Coastal Research
Description | Identification of different types of rip circulation patterns; exit and rotation, and the characterisation of environmental conditions in the surf zone that are particularly hazardous to bathers. |
Exploitation Route | Preparation of educational material for RNLI life guards; development of rip warning system in collaboration with Met Office; Exploitation of the results to the RNLI and through collaboration with the Met Office. Beach hazard tool developed in collaboration with Met Office that is being used to help manage RNLI lifeguard resources. |
Sectors | Environment,Leisure Activities, including Sports, Recreation and Tourism |
URL | http://www.research.plymouth.ac.uk/coastal-processes/DRIBS/DRIBS.html |
Description | Production of on-line training material for RNLI lifeguards. Existing material was updated and revised to include the latest research findings of the implications of rip currents for bather safety. Development of a marine weather and rip hazard forecast for lifeguard operational management, currently in use and constantly under review for improvement. Development of new beach and rip current risk assessment tools for RNLI risk assessors. Scientific findings have been exploited by the RNLI to update and inform public awareness and education programs. Several follow-up grant proposals have been submitted, also with the RNLI, but also involving other EU lifeguard organisations, but these have been unsuccessful. The research has now also applied to New Zealand where a bespoke rip hazard tool will be developed for the beaches in the Auckland region as part of consultancy, and in South Africa, in collaboration with South African lifeguards. Most recently, the general modeling approach developed as part of the DRIBBS project has also been applied to Crantock beach, SW England, also in collaboration with the RNLI. |
Sector | Education,Environment,Leisure Activities, including Sports, Recreation and Tourism |
Impact Types | Societal |
Description | Advice Environment Agency on coastal protection |
Geographic Reach | Local/Municipal/Regional |
Policy Influence Type | Implementation circular/rapid advice/letter to e.g. Ministry of Health |
Description | Collaboration with the Met Office |
Organisation | Meteorological Office UK |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | As part of the Plymouth University, RNLI and Met Office partnership, a regional rip prediction tool was produced. the tool was trailed over the 2013 summer and is currently under review. |
Collaborator Contribution | Met Office - Support during rip tool research and development. Operational 5-day wave and weather forecast, forecast distribution, formatting development and rip forecast model development. |
Impact | Scott, T., Masselink, G., Austin, M.J., Russell, P.E., 2014. RNLI lifeguard Operation Marine Forecasts: Peak Season Trial Report 2013 (internal) Daily Operational Marine Forecast, trialled during peak season with RNLI lifeguards at selected beaches. Under trial 2013/2014. |
Start Year | 2012 |
Description | Southampton University |
Organisation | University of Southampton |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | I am currently co-supervising a PhD student (Seb Pitman), based at Southampton University, based on the topic of rip current dynamics and beach safety. This is a continuation of the DRIBS work. |
Collaborator Contribution | Papers submitted by the PhD student |
Impact | Pitman, S., Gallop, S.L., Haigh, I.D., Masselink, G. and Ranasinghe, R., 2016. Wave breaking patterns control rip current flow regimes and surf zone retention. Marine Geology, 382, 176-190. [http://dx.doi.org/10.1016/j.margeo.2016.10.016] |
Start Year | 2014 |
Description | Manonabeach - Tim Scott Perranporth DRIBS interview |
Form Of Engagement Activity | A magazine, newsletter or online publication |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | Increased public awareness of project n/a |
Year(s) Of Engagement Activity | 2011 |
Description | NERC Planet Earth Podcast |
Form Of Engagement Activity | A magazine, newsletter or online publication |
Part Of Official Scheme? | Yes |
Geographic Reach | National |
Primary Audience | Public/other audiences |
Results and Impact | Generated public and media interesting in the research. Continued the effort to reach and impact a broad public audience with our reserach findings in an effort to improve beach safety. |
Year(s) Of Engagement Activity | 2011 |
URL | http://planetearth.nerc.ac.uk |
Description | NERC Planet Earth Podcast and Magazine (adapted transcript). |
Form Of Engagement Activity | A magazine, newsletter or online publication |
Part Of Official Scheme? | Yes |
Geographic Reach | National |
Primary Audience | Public/other audiences |
Results and Impact | Podcast and online publication created interest in our research from a broad range of public and media. Generated media interest that led to greater exposure and increased profile of research. |
Year(s) Of Engagement Activity | 2011 |
Description | National Oceanography Center Liverpool: Invited seminar. |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | Yes |
Geographic Reach | Regional |
Primary Audience | Other academic audiences (collaborators, peers etc.) |
Results and Impact | Disseminated project findings to wider academic audience. No notable impacts. |
Year(s) Of Engagement Activity | 2011 |
Description | Public lecture, Perranporth |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Public/other audiences |
Results and Impact | A public lecture held at the local council offices at Perranporth. Lecture was aimed to provide the local community an opportunity to learn more about our rip current research at Perranporth. Scott, T. M. April 2012. The science of rip currents. Public presentation, Council Offices, Perranporth, Cornwall. Positive feedback from audience with interesting discussion. |
Year(s) Of Engagement Activity | 2012 |
Description | RNLI Offshore Magazine |
Form Of Engagement Activity | A magazine, newsletter or online publication |
Part Of Official Scheme? | Yes |
Geographic Reach | National |
Primary Audience | Public/other audiences |
Results and Impact | Article received a positive response via social media Reportedly raised awareness of rip current dynamics and implications for beach safety. Article provided key basic science on rip currents. |
Year(s) Of Engagement Activity | 2014 |
Description | RoSPA National Water Safety Forum Regional Chairs Meeting and Presenters Workshops. |
Form Of Engagement Activity | A formal working group, expert panel or dialogue |
Part Of Official Scheme? | Yes |
Geographic Reach | National |
Primary Audience | Professional Practitioners |
Results and Impact | Positive feedback from members of audience as to the usefulness of the research for coastal safety. Presentation and discussion led to new contacts and collaborations. |
Year(s) Of Engagement Activity | 2010,2012 |
Description | Surf Life Saving Great Britain National Update Meetings |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | Yes |
Geographic Reach | National |
Primary Audience | Professional Practitioners |
Results and Impact | This talk always stirred a good response. Lifeguards are very passionate about their work and were often engaged in the new findings. The annual talk provided the opportunity to raise the profile of the research and drip feed findings from our research to the end-user. Lifeguards were notably provoked into considering their basic understanding of some nearshore oceanography and processes and the explanations it provided for observational experience. |
Year(s) Of Engagement Activity | 2011,2012,2013 |
Description | University Alliance Magazine: Problem Solved - Saving Lives at Sea. |
Form Of Engagement Activity | A magazine, newsletter or online publication |
Part Of Official Scheme? | Yes |
Geographic Reach | National |
Primary Audience | Public/other audiences |
Results and Impact | Unknown |
Year(s) Of Engagement Activity | 2012 |
URL | http://www.unialliance.ac.uk/campaigns/problemsolved. |
Description | World Conference on Drowning Prevention 2013 |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | Yes |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Induced informed discussion amongst beach safety practitioners. Facilitated a change in thinking towards lifeguard training and risk assessment with a number of agencies stating they would use content to update their training programs. |
Year(s) Of Engagement Activity | 2013 |