iCOAST: Integrated COASTal sediment systems

Lead Research Organisation: Swansea University
Department Name: College of Engineering

Abstract

Prediction of changing coastal morphology over timescales of decades raises scientific challenges to which there are not yet widely applicable solutions. Yet improved predictions are essential in order to quantify the risk of coastal erosion, which is significant in its own right and also one of the main mediators of coastal flood risk. Whilst 'bottom-up' process-based models provide valuable evidence about hydrodynamic, sediment transport and morphodynamic processes in the short term, their predictive accuracy over scales of decades is for the time being fundamentally limited. Meanwhile, behavioural systems models, that focus on the main processes and feedback mechanisms that regulate coastal form have been shown to have predictive capability at the mesoscale (10-100 years and 10-100 km). However, their application has been limited to a rather narrow sub-set of coastal forms.
The iCoast project is based upon a hierarchical systems concept which combines (i) the beneficial features of process-based models, (ii) a new generation of coastal behavioural systems models, and (iii) an extended approach to coastal systems mapping, which can be used to systematise and formalise different sources of knowledge about coastal behaviour. All the software developed within iCoast will be open source and OpenMI compliant.
The research is focussed upon four deliverables that have been identified as major challenges in the NERC Natural Hazards Theme:
Deliverable 1 will be an overall systems framework. The successful approach to coastal systems mapping developed by French et al. will be extended and applied to all of the England and Wales, making use of a new systems mapping tool. These new coastal systems maps can both supersede the coastal cells and sub-cells currently used in shoreline management planning and provide an evidence-based framework for more quantitative modelling. Therein, hydrodynamic and sediment transport coastal area models will be implemented at a broad spatial scale in order to provide evidence of wave and tidal forcings and sediment pathways. The systems framework will be implemented in open source software tools and coupled with methods for uncertainty analysis.
Deliverable 2 will provide a new generation of behavioural geomorphic modules, which can be linked to enable simulation of coupled coastal-estuary-offshore landform behaviour at a meso-scale. Existing reduced complexity behavioural modules, several of which are held in-house within the iCoast consortium (SCAPE, ASMITA, various versions of 1-line beach models) will be reviewed and development and incremental improvement opportunities will be identified. They will be researched intensively by a team with unique experience of this type of model development. The scope of data-based modules that can exploit the growing datasets from coastal observatories will also be extended. The models will be integrated within a systems framework in order to study emergent properties and explore key sensitivities.
Deliverable 3 will entail application and validation of two distinct coastal regions: the Suffolk Coast (Sub-Cell 3c) and Liverpool Bay (Sub-Cells 11a/11b), exploring the sensitivities of these coastal regions to changes in sediment supply resulting from sea-level rise, climate change and coastal management scenarios. This will yield the results needed for high impact publication and the demonstrations that are essential to build confidence in new approaches being transferred into practice.
Deliverable 4 will facilitate knowledge transfer of the new methods through a range of dissemination mechanisms, including tutorials, manuals and knowledge transfer workshops. Our open source modelling strategy will initiate a community modelling approach in the coastal research community, at the same time as maximising access by practitioners to the knowledge generated at a time when requirements for coastal adaptation urgently require new predictive capability.

Planned Impact

The beneficiaries from the research fall into two main categories:
1. The worldwide coastal research community, who recognise the difficult problem of mesoscale coastal prediction, and hence will be eager to take up new methodologies. This is evidenced by the rapid uptake of the SCAPE model, which has now been applied in New Zealand and the Great Lakes as well as at several sites in the UK.
2. Coastal practitioners in the UK and worldwide, urgently need new mesoscale predictions of coastal change in order to manage the risks of coastal erosion and coastal flooding. These coastal risks are profoundly influenced by the long term behaviour of coastal sediment systems, but existing predictive approaches are severely limited, especially in conditions of long term change. Coastal practitioners include those in government and its agencies (e.g. the Environment Agency) and those in local authorities with responsibility for coastal management and adaptation. Whilst the focus of the research is upon UK coasts, the leading UK coastal consultants (e.g. Halcrow, HR Wallingford, Royal Haskoning) have considerable international businesses, so the UK is expected to benefit through the exploitation of iCoast science by these organisations in their international businesses.
Ultimately, coastal communities will benefit from more sustainable coastal management that is based upon dependable predictions of coastal change. This will help to reduce the risks from flooding and coastal erosion and help to ensure that the costs of coastal management do not become unmanageable in future, even in the context of a changing climate. Improved and evidence-based coastal management will also help to sustain coastal ecosystems, which are threatened by sea level rise and coastal squeeze and protected under the Habitats and Birds Directive.
The benefits from the research will derive from the developed methods for enhancing understanding and predicting processes of coastal change. Enhanced understanding will be delivered in particular via the new tools for systems mapping, which have already proved to be a worthwhile approach to formalising knowledge of coastal processes but which will be considerably extended in the course of the iCoast research. The process of developing behavioural geomorphic models will yield new insights into the controls upon coastal change and the ways in which coasts may be modified by changed environmental forcings. The coastal area modelling will yield new insights into the complex processes of sea bed sediment transport.
Of most practical benefit will be the new predictive tools that are developed in the iCoast project. These will take a number of different forms, including coastal area models, data-based methods and behavioural geomorphic models. They will all be developed with a focus upon predicting the variables of most relevance to coastal managers, along with well justified uncertainty estimates. The application of the tools from iCOAST will directly contribute to future revisions of the Environment Agency's Long-Term Investment Strategy and the UK Government's strategic goals with respect to the adaptation to, and mitigation of, climate change. It will also help with other needs such as the Water Framework Directive and other legislation.
There is a realistic prospect that innovations in the iCoast project will be rapidly taken up in practice. There is an urgent need for better predictive models to analyse coastal risks and justify coastal adaptation strategies. Strong links with the practitioner community and well developed knowledge transfer mechanisms mean that outputs can be transferred into practice as soon as they are demonstrated and validated. These innovations need not wait till the end of the project to be taken up in practice.
The iCoast project will contribute to the development of a range of research and professional skills in the research team and amongst the project stakeholders with whom we interact.

Publications

10 25 50
 
Description Our research has been on improving our understanding of meso-scale coastal shape change. that is, how the beach and shoreface changes over periods of decades. Our research focussed on 3 areas:
1) Analysis of the equations governing sediment transport and shoreface evolution to investigate how these could be simplified for longer term forecasting
2) Investigation of patterns of interannual beach evolution and their relation (if any) to the prevailing wave conditions
3) Exploration of simple beach models to improve our understanding of their limitations.

Under (1) we have made some theoretical advances that indicate that the equations may, under suitable assumptions, be simplified to a diffusion-type form. This is a form of equation that is often used in morphodynamics but is rarely justified beyond the fact that it provides 'reasonable' results. Our work provides some theoretical justification for this type of modelling.
Under (2) we have collated and analysed extensive sets of beach profile measurements and wave conditions. Beach profiles are survey lines across a beach, from the beach crest to low water, or beyond. We have analysed data from Poland, Australia, USA and the main study site in the UK, the Suffolk shoreline. We have found that the beach profile can be correlated well with the probability density distribution of significant wave heights between successive surveys. The form of this correlation varies from site to site but can be used to provide useful forecasts of beach shape on the basis of forecasts of wave conditions. This has been tested through 'hindcasting' the beach evolution at 4 sites over periods of 5 to 10 years. As waves are generally easier to forecast well than beach profiles, an analysis of historical beach profile measurements - becoming more widespread due to coastal monitoring programmes set up as part of the UK Shoreline Management Plans - provides an alternative, independent source of prediction to numerical models, and provides the shoreline manager with a 'second opinion'. The statistical method is site-specific and will only predict behaviours encapsulated in the historical records.
Under (3) we have undertaken a stability analysis of the 1-line beach model, and its extensions to 2 and 3 line models. Such models are used widely in research as well as engineering studies. While the 1-line model has appeared robust, its 2 and 3-line variants have suffered from sensitivities and instabilities. Our stability analysis has identified that while the 1 -line model is stable, the 2 and 3-line models contain intrinsically unstable modes which can be excited under certain conditions. This has provided an explanation for the problems encountered in the application of 2- and 3-line models.
Exploitation Route (1) In the development of simplified coastal morphodynamic models
(2) In (or as part of) the prediction of mesoscale evolution of shorelines for coastal management
(3) In the development and extension of numerical solution methods for shoreline evolution models.
Sectors Aerospace, Defence and Marine,Environment

URL https://www.channelcoast.org/iCOASST/introduction/
 
Description The findings of this work, together with the findings from others in the research consortium, are being developed by the Environment Agency into tools for their staff to use in their national role of flood and coastal erosion risk management. Further studies on the beach profile measurements taken by the EA along the Suffolk coast have been concluded and published in a paper in Geomorphology (2019). The findings have direct application to the Coastal Councils along this stretch of the coast, and are of broader international relevance to similar coastal environments.
First Year Of Impact 2016
Sector Aerospace, Defence and Marine,Environment
Impact Types Societal,Economic

 
Description Innovative monitoring
Amount £63,532 (GBP)
Funding ID NE/R014485/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 01/2018 
End 06/2018
 
Title Beach Profile Analysis 
Description The model performs a canonical correlation analysis of a time series of beach profiles and wave conditions to assess patterns of behaviour within the database of measurements. One output is a correlation matrix which can be used to link the state of the beach profile to the preceeding wave conditions. 
Type Of Material Data analysis technique 
Year Produced 2015 
Provided To Others? Yes  
Impact No notable impacts. 
 
Description Cardiff University 
Organisation Cardiff University
Department School of Engineering
Country United Kingdom 
Sector Academic/University 
PI Contribution Assisted with IMA Conference preparations and participated in the Project Workshop in March 2015
Collaborator Contribution Assisted with IMA Conference preparations and participated in the Project Workshop in March 2015
Impact Papers at the IMA COnference
Start Year 2015
 
Description One day meeting - Project summary 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Further work on the models developed during the project has been undertaken in-house by the Environment Agency.
Year(s) Of Engagement Activity 2016
URL http://www.icoasst.net/Outputs/conferences/conference_2016/