Response of Ecologically-mediated Shallow Intertidal Shores and their Transitions to extreme hydrodynamic forcing in UK settings (RESIST-UK)

Salt marshes exist around the globe on low-lying, low gradient coastal fringes. Amongst providing many services to society (valued at around £1,500 per hectare per year), they are valued for their ability to protect coasts from the erosive force of waves and tides, even during extreme storm surge events. They are, however, nationally and globally in decline. In the UK, the area of salt marsh reduced by 13% between 1945 and 2010 (from 37,300 to 32,500 ha). This loss has not been compensated for through marsh restoration efforts (only 1,320 ha created by 2012). There is high uncertainty as to how these natural coastal protection features (or their artificially restored or re-created equivalents) will respond to the combined effects of future changes in sea level and possible changes in the magnitude and/or frequency of storms.

The grass/shrub covered surfaces of salt marshes appear remarkably resistant to storm impact. Given sufficient sediment supply, they can also 'grow' vertically to track rising sea levels. The loss of marsh area over time is therefore more often due to a landward retreat of their most seaward margin or the lateral widening off the tidal channels that drain them. These boundaries are often undercut, with marsh material loosened and removed by tidal currents and waves. Such retreat may reach several metres per year and is of great concern to coastal engineers, planners, and managers, relying on the 'storm buffering' function of these environments.

We know little about the force required to 'cut into' salt marsh material (the 'substrate'). The substrate itself is composed of sediment laid down over time by the tides, alongside organic materials resulting from plant growth and invertebrates living in the soil. Its resistance to wave or tidal forces therefore varies within and between marshes. But this resistance has not, so far, been measured in a way that allows coastal engineers to take it into account when predicting the impact of future environmental scenarios (e.g. greater water depths and stronger tidal currents or waves).

In this project, we will sample and analyse in detail the substrate of a more sandy (Warton, Morecambe Bay) and a more muddy (Dengie, Essex) marsh, as well as of two restored marshes (two East coast managed realignment sites) and their adjacent natural equivalents. We will determine what these substrates are composed of, how this varies between and within each of these marshes and how it affects the resistance of the marsh substrate to wave and tidal forces. State-of-the-art technology (unmanned aerial vehicles (UAVs) or 'drones') and the latest satellite products will then allow us to produce a map of the physical marsh vulnerability of marsh systems, both in their entirety and within marsh, to these types of forces.

Coastal planners, engineers, and managers will benefit through being able to better predict marsh loss into the future and design suitable preventative measures. Anyone watching our three-part documentary short film series will benefit through a better understanding of the scientific methods we use. The global community already using existing satellite products built into web-based tools for assessing the coastal protection function of salt marshes will benefit by being able to access predictions of the resistance to wave/tide erosion that we will build into those tools.

This project will have significant impact with real benefits accruing to society and economy, nationally and globally. It deals with a global problem and offers globally transferrable solutions. In doing so, the project team builds on many years of collaboration between each of the PI/Co-Is and a wide group of their respective contacts within the coastal management community in government, non-government, and private organisations. Existing stakeholder contacts established through NERC BLUEcoast, NERC CoastWEB, and EU FP7 FAST and RISC-KIT will enable a quick and efficient communication network to be set up through which RESIST-UK impact activities will be promoted and evaluated.

RESIST-UK will work with the UK coastal management community (those who manage the coast, those with stewardship roles and who provide expert commercial advice), providing them with predictions of salt marsh vlunerability to wave/tide forcing and much needed evidence to underpin better, and more sustainable management decisions.. Within the UK, a close working partnership will be set up with representatives from the private sector, Local/Regional Government, National Government agencies and non-government organisations. Representatives these organisations will be invited to two national project workshops (working partnership group meetings) hosted in Cambridge via the Centre for Science and Policy (CSaP) and followed by two webinars. Topics of discussion will focus on incorporation and use of the Physical Marsh Vulnerability (PMV) index into / alongside monitoring and decision frameworks. Regular contact between the RESIST-UK lead (Möller) and organisational representatives will allow for a two-way exchange of information between the RESIST-UK partners and interested parties on the formulation of the PMV, and its further development beyond the end of the project. Such collaboration may take the form of an application for an Industrial Research Fellowship.

RESIST-UK will provide input into a global coastal foreshore stability assessment tool. The qualitative PMV index will greatly assist the global user community in its use of the EU FAST ('Foreshore Assessment using Space Technology', fast-space-project.eu) project's MI-SAFE package of services (see http://fast.openearth.eu/). The delivery of these services is supported by Deltares (NL), a not-for-profit institute with global reach, who will maintain the web app at no cost to this project. The addition of information on physical salt marsh vulnerability in the form of the PMV index will make a real and lasting contribution to this valuable management tool.

The British Geological Survey's national coastal vulnerability index (CVI) will be updated with outputs from RSIST-UK. New knowledge and understanding regarding the susceptibility of salt marshes to erosion will extend and improve the BGS's coastal vulnerability index. Dr Kate Royse will liaise between RESIST-UK and the respective CVI developers within the BGS to achieve seamless exchange of information and analysis methods, such that future iterations of the CVI will draw directly on the insights into marsh substrate resistance (and its spatial variability) derived from RESIST-UK. The UK coastal management and engineering community will benefit directly from this CVI update.

RESIST-UK will contribute directly towards a more scientifically-literate society by producing and disseminating widely three short 3-5 minute films (produced by Cambridge Filmworks, a company with a track record of producing high-quality, attractive and accessible educational short films), explaining scientific focus, societal value, x-ray, flume, and remote sensing methods, project outputs and their application. A range of educational materials will be produced for use at GCSE to A-level Geography in schools. Web-site, blog, and social media feeds will increase exposure of impact materials produced and allow impact to be evaluated.