UKGravelBarriers
Team
This research project is possible thanks to the close collaboration between researchers from the British Geological Survey (BGS), UK Centre for Ecology and Hydrology (UKCEH), and the University of Nottingham (UoN), coastal engineering practitioners from Kenneth Pye Associates (KPAL), Moffat and Nichol (M&N), professional Earth Observation providers from ARGANS Ltd and isardSAT, with the in kind support of professionals from the Centre for Environment Fisheries and Aquaculture (CEFAS), the Royal Society for the Protection of Birds (RSPB), the Environmental Fluid Dynamics Research Group of the University of Granada (GDFA), the Agri-Food and Biosciences Institute (AFBI), the Geological Survey of Northern Ireland (GSNI), the Wales Coastal Monitoring Centre (WCMC), and from government organizations such as Natural Resources Wales (NRW) and the Environment Agency (EA)
Research approach
Hypothesis
To answer the research questions, we have adopted two main research hypotheses.
H1: The topography and shallow-subsurface-structure of gravel barriers, including the backshore and nearshore areas control their short-term (overwash) to long-term (transgression) evolution in response to changes in sea level rise, storminess, and sediment supply.
H2: The critical interactions between gravel barriers and the back-barrier environment as well as the interplay between gravel barriers and coastal structures can be quantified from both field and numerical simulations under the assumptions of space-for-time substitution [1] and the use of appropriate complexity modelling [2].
Scope
The spatial-scope of this research will cover all gravel beaches in the United Kingdom (England, Wales, Scotland and Northern Ireland). The temporal-scope will cover their evolution over the last 20,000 thousand years (e.g. to explore both creation of gravel barrier and evolution under different sea level rise scenarios) and will explore how they might evolve in the future to 2150.
Gravel beaches types may be categorised according to the mixture of sands and gravels present, which has a significant influence on the beach slope and the more general morphological response of the beach to wave action. Three categories are defined[3][4] as pure gravel (G), mixed sand and gravel (MSG) and composite sand and gravel (CSG).
- Pure gravel beaches have steep slopes (tan β = 0.08–0.24) and gravel extending from the storm berm to below the mean low water spring tide level.
- MSG beaches have moderate slopes (tan β = 0.04–0.13), with sand and gravel entirely mixed both across shore and at depth.
- CSG beaches have a steep gravel berm fronted by a low-angle intertidal terrace, with over all beach slopes of tan β = 0.05–0.14. On composite beaches, there is distinct hydrodynamic cross-shore sorting of the sand and gravel component.
Objectives
The objectives of this project are listed below, with the research questions that they address indicated;
- O1: Review the responses of gravel barriers to the relative sea level changes observed from 20,000 years to about 100 years ago, including periods when sea levels (see Fig 1) generally rose at different rates but also remained with little change over large periods (RQ#1, RQ#4).
- O2: Review the performance of gravel barriers over the last two decades where the Environment Agency discontinued a policy of managing sea defences by reshaping of gravel barrier profiles and we have access to more detailed observations (RQ#1).
- O3: Collect new field data to improve our understanding of sediment transport on gravel barriers, their shallow subsurface structure and effects of hydraulic conductivity on storm (individual) and decadal evolution (RQ#3, #5).
- O4: Develop a broad-scale simulator of the evolution of a selected coastal barrier and backshore habitat, that account for changes in climate change, sediment supply and management interventions extending to 2150 (RQ#2, #5, #6).
- O5: Quantify the critical interactions between gravel barriers and the back-barrier environment as well as the interplay between gravel barriers and coastal structures in representative field studies (RQ#2, RQ#6).
- O6: Curate the data and models produced in this project beyond the lifetime of the project to enable further research and support decision making.
Program of work
To deliver the project objectives we have organised the work in five work packages:
WP 0 is where all the activities related with project management and coordination are integrated. This includes one in person meeting per year with all project partners and embedded practitioners that will act as project steering group and expert group providing data, access to networks and know-how. The main activities, milestones and deliverables of the WP1 to WP4 are summarised in the table below.
Fundamental to our approach is that:
- Successful prediction of long-term barrier behaviour requires broad representation of the coastal systems of which they are a single part, and that,
- Modelling capability is improved in terms of prediction and relevance to coastal management decision making by integrating the expertise of successful and established practitioners in coastal geomorphology with numerical modellers of coastal processes.
Overall, through system analysis and numerical modelling, based on four work packages, we will map and quantify gravel barrier responses to individual, ‘violent’, events such as storms in the context of longer-term ‘progressive’ impacts such as sea level rise, changes in sediment sources, and human interventions. New process understanding will be achieved by seamlessly combining innovative field observational approaches of surface and subsurface processes with advanced numerical modelling. The long-term numerical simulations will be based on predicted scenarios of sea level rise, increased wave heights and changes in coastal orientation based on UKCP18 and other recent climate change studies. The results will support improved and sustainable coastal management based on the improved understanding of how gravel barriers evolve over longer time scales under different climate conditions and human intervention scenarios. They will be a significant advance from the new comprehensive and novel, multi-scale observations of key processes that drive long-term gravel beach morphodynamic evolution.
| Work Package | Activities | Milestones | Deliverables |
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WP1: Spatial distribution and temporal evolution of UK gravel barriers and their back barrier ecosystems. |
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WP2: Field data collection at selected case study sites |
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WP3: Development of a broad-scale gravel barrier simulator |
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WP4: Quantify interactions and management intervention thresholds |
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Outcomes
Holistic understanding of the complex interactions and feedbacks between the sediment composition of the shallow subsurface, nearshore morphodynamics in response to both storms and sea level changes.
A new community modelling system coupled with terrestrial, marine and groundwater sectors and produce numerical simulations which can be used to support multi-hazard analyses under present and future climate change scenarios. These deliverables will be combined with an assessment of the role of coastal habitats, resulting in national maps for protective services and vulnerabilities of coastal habitats to climate-driven multi-hazards. We will also provide tools to analyse the efficacy of future coastal management schemes.
These will deliver a step change in the management of gravel coastlines in the UK.
History
This project started in response to the NERC funding opportunity called "Addressing environmental challenges: NERC highlight topics 2023" (Topic F: ‘Building understanding of natural coastal protection by gravel barriers in a changing climate’). The call was considered to be well aligned with the British Geological Survey science strategy plan 2023-2028 and in particular with the strategic priority on living with geological hazards: to mitigate and adapt to risk, we will monitor, characterise and forecast earth hazard events and their likely impacts by improving harmonisation in hazard and risk analysis, as well as focusing on hazardous climate change. The team was officially notified on the reception of this award on the 31st of January 2024 and the project started the 1st of February of 2024. Lead Grant Reference: NE/Y503265/1
Media coverage
References
- ↑ Muñoz López, P., Payo, A., Ellis, M.A., Criado-Aldeanueva, F. and Owen Jenkins, G., 2020. A method to extract measurable indicators of coastal cliff erosion from topographical cliff and beach profiles: Application to North Norfolk and suffolk, East England, UK. Journal of Marine Science and Engineering, 8(1), p.20. Open source paper [1].
- ↑ French, J., Payo, A., Murray, B., Orford, J., Eliot, M. and Cowell, P., 2016. Appropriate complexity for the prediction of coastal and estuarine geomorphic behaviour at decadal to centennial scales. Geomorphology, 256, pp.3-16. Open source paper [2].
- ↑ Anthony, E. J. (2008). Chapter Six Gravel Beaches and Barriers. Developments in Marine Geology. E. J. Anthony, Elsevier. Book chapter [3].
- ↑ CoastalWiki' Gravel Beaches Types.
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