Gravel barriers and beaches consists of sediments coarser than 2 mm and are very common in England and Wales. They extend along more than 1,000 km of its coastline and protect low-lying back-barrier regions from flooding, and coastal cliffs from undercutting during storm events. Their importance to society is widely acknowledged and coastal engineering structures (e.g., seawalls and groins) and management techniques (recharge, recycling and reshaping) are extensively used, at significant cost, to maintain and enhance their protective ability. Unfortunately, as highlighted in a recent report commissioned by DEFRA, regular breaching and extensive storm damage has occurred at many gravel barrier sites in the UK, and this is likely to increase in the future as a result of sea-level rise and enhanced storminess due to climate change. The DEFRA report concludes that limited scientific guidance is currently available to provide beach managers with operational management tools to predict the response of gravel barrier and beaches to storms. Specifically, we are currently unable to predict under what conditions a gravel barrier will withstand a certain storm event, or whether the barrier will be overwashed, or even breached. Similarly, we have no means of evaluating the effect of certain management interventions (seawall construction, beach nourishment, profile reshaping) on gravel barrier stability.The principal aim of the proposed research is therefore to obtain new understanding of storm impacts on gravel beaches and barriers, and to develop a predictive tool that is capable of modelling these impacts. Rather than developing a new model from first principles, our approach is to use an existing model that has been applied successfully to sandy beaches and modify the model for use on gravel beaches using field data. The model used as a starting point is the XBeach model, which has been specifically been developed to predict hurricane impacts on sandy barriers.The proposed research is best summarised by the following closely linked objectives. (1) A 4-week field experiment will be held on a gravel beach to measure swash processes, sediment transport and beach response under a range of wave conditions, including a storm. (2) These field data will be used to help modify, parameterise and calibrate the existing XBeach model so it can be used for gravel beaches. (3) An additional field data set on storm response will be collected on nine UK gravel barrier systems, representing a range of morphological, sedimentological, wave and water level conditions. (4) These field data will be used to validate and verify the XBeach model developed under (2). (5) A tool will be developed for end-users, based on the model formulated under (4), for predicting berm formation, overtopping, overwashing and breaching of gravel beaches and barriers. The 3-year project is led by Professor Gerd Masselink and involves two co-investigators, one post-doctoral research fellow, one project student, two Visiting Researchers and two Project Partners. The research team is ideally placed to conduct the proposed research, because over the past 5 years they have acquired: (1) knowledge and understanding of gravel beach dynamics under calm and energetic conditions: (2) experimental capability and instrumentation for measuring gravel beach morphodynamics under storm conditions; and (3) expertise with XBeach to customise the model for use on gravel beaches. Involvement of two Project Partners (one from industry and one from government) will ensure that the results from this research will be appropriately disseminated and used for practical applications.

The Surface Water and Ocean Topography (SWOT) mission will provide for the first time from space two-dimensional high-resolution maps of surface water levels globally over ocean and inland waters. If SWOT meets its performance targets, it will represent a major milestone in our ability to observe, study and understand the nature and evolution of the Earth's marine and land surface water systems, globally. The UK Space Agency invested in SWOT jointly with the US NASA, French CNES and Canadian Space Agency to enable the implementation and launch of this mission. The SWOT-UK project proposes a comprehensive programme of campaigns and multidisciplinary research centred on the Bristol Channel and River Severn region as the UK contribution to the international SWOT Science Team validation efforts. In accordance with the requirements of the NERC/UKSA SWOT CalVal call, SWOT-UK takes an open and inclusive approach, putting special emphasis on disseminating value-added SWOT validation datasets and engaging with the wider UK science and stakeholder communities to raise awareness of the SWOT capabilities.

Many countries with a sea border need manmade defences to protect them from coastal hazards such as flooding. In the UK 3200 kilometres of coastline are defended, particularly in seaside towns and cities. This is to prevent flooding and to protect people, property and infrastructure from the harm caused by large waves that can occur when a severe storm happens at the same time as a high tide. Building strong coastal defences can be costly, often about £10,000 per meter, and needs careful planning. When planning coastal defences a lot of data are needed to understand the potential hazards that might occur in decades to come. To obtain this data for a particular site usually means monitoring the local tides, wave heights, and beach levels for a period of 5 to 10 years. These data are used in numerical tools (e.g. EurOtop) to test which seawall design is most suitable and how high it needs to be to provide protection for the next 100 years. The tools do this by estimating the "overtopping hazard" for each design, i.e. what volume of water might come over the wall during storm conditions. Accuracy of the tools is assessed by checking outputs against measurements of overtopping volumes during storms. Field experiments have previously used large tanks placed behind the seawall to catch the water that comes over. Such experiments are very costly and can be difficult to do, so only a few have been made - usually at sites with very different structures (e.g. dikes) and for only a few days. They also only provide a limited amount of data and none at all on the speed of the water that overtops: an important factor for public safety. This lack of measurements means there is large uncertainty in the numerical estimates of the hazards, so sea defences are overdesigned to have large safety margins and may therefore cost much more than they need to. This project aims to take a low-cost instrument that has previously been used to measure waves in the open ocean, and convert it into a system ("WireWall") that will measure coastal overtopping hazard. Recent improvements in technology now make it possible to measure at the very high frequencies required to record the fast moving overtopping water (a few hundred times a second for a jet of water travelling up to 100 mph). The system will employ a 3-dimensional grid of capacitance wires that sense contact with saltwater. This signal will be used to measure the volume and speed of overtopping at vulnerable locations on the 900-meter-long seawall at Crosby in the North West of England. This seawall is reaching the end of its design life and intense monitoring of the local conditions has begun to aid the design of a new wall. This project includes engineers, environmental hydraulics experts and oceanographers who have complementary field, laboratory and modelling expertise. Our project partners (Sefton Council, Environment Agency, Balfour Beatty, Marlan Maritime Technologies and Channel Coastal Observatory) are involved in commissioning, designing and constructing coastal defences, and include government authorities and private consultancies. They will provide existing monitoring data at Crosby, and will advise on the methods and tools routinely used in the design of a new seawall. We will use this information to optimise the configuration of the WireWall system and its deployment at Crosby. Data obtained by WireWall will improve the tools used when designing the new seawall by calibrating the numerical estimates of overtopping hazards to those observed. In the future WireWall could be incorporated into new seawall structures to enable long-term monitoring. The ability to observe trends and abrupt changes in hazardous conditions (due to defence degradation, climate change and sea level rise) would support shoreline management plans and provide data to validate operational flood forecasting systems. Keywords: Shoreline monitoring; Coastal defence; Wave overtopping hazard

Many countries with a sea border need manmade defences to protect them from coastal hazards such as flooding. In the UK 3200 kilometres of coastline are defended, particularly in seaside towns and cities. This is to prevent flooding and to protect people, property and infrastructure from the harm caused by large waves that can occur when a severe storm happens at the same time as a high tide. Building strong coastal defences can be costly, often about £10,000 per meter, and needs careful planning. When planning coastal defences a lot of data are needed to understand the potential hazards that might occur in decades to come. To obtain this data for a particular site usually means monitoring the local tides, wave heights, and beach levels for a period of 5 to 10 years. These data are used in numerical tools (e.g. EurOtop) to test which seawall design is most suitable and how high it needs to be to provide protection for the next 100 years. The tools do this by estimating the "overtopping hazard" for each design, i.e. what volume of water might come over the wall during storm conditions. Accuracy of the tools is assessed by checking outputs against measurements of overtopping volumes during storms. Field experiments have previously used large tanks placed behind the seawall to catch the water that comes over. Such experiments are very costly and can be difficult to do, so only a few have been made - usually at sites with very different structures (e.g. dikes) and for only a few days. They also only provide a limited amount of data and none at all on the speed of the water that overtops: an important factor for public safety. This lack of measurements means there is large uncertainty in the numerical estimates of the hazards, so sea defences are overdesigned to have large safety margins and may therefore cost much more than they need to. This project aims to take a low-cost instrument that has previously been used to measure waves in the open ocean, and convert it into a system ("WireWall") that will measure coastal overtopping hazard. Recent improvements in technology now make it possible to measure at the very high frequencies required to record the fast moving overtopping water (a few hundred times a second for a jet of water travelling up to 100 mph). The system will employ a 3-dimensional grid of capacitance wires that sense contact with saltwater. This signal will be used to measure the volume and speed of overtopping at vulnerable locations on the 900-meter-long seawall at Crosby in the North West of England. This seawall is reaching the end of its design life and intense monitoring of the local conditions has begun to aid the design of a new wall. This project includes engineers, environmental hydraulics experts and oceanographers who have complementary field, laboratory and modelling expertise. Our project partners (Sefton Council, Environment Agency, Balfour Beatty, Marlan Maritime Technologies and Channel Coastal Observatory) are involved in commissioning, designing and constructing coastal defences, and include government authorities and private consultancies. They will provide existing monitoring data at Crosby, and will advise on the methods and tools routinely used in the design of a new seawall. We will use this information to optimise the configuration of the WireWall system and its deployment at Crosby. Data obtained by WireWall will improve the tools used when designing the new seawall by calibrating the numerical estimates of overtopping hazards to those observed. In the future WireWall could be incorporated into new seawall structures to enable long-term monitoring. The ability to observe trends and abrupt changes in hazardous conditions (due to defence degradation, climate change and sea level rise) would support shoreline management plans and provide data to validate operational flood forecasting systems. Keywords: Shoreline monitoring; Coastal defence; Wave overtopping hazard

A 1 m sea level rise is almost certain in the next century and it is estimated that 20% of England's coastal defences could fail under just half this rise. Ambitious climate mitigation and adaptation plans may protect 400,000 - 500,000 people, but flood and coastal erosion risks cannot be fully eliminated - we cannot build infinitely high sea walls. Worldwide 150 million people could be affected by sea level rise in the next 30 years. Better ways to measure, forecast, warn of and respond to coastal flooding are thus required. Using Penzance and Dawlish we will demonstrate a new monitoring system able to issue vital real-time hazard alerts and flood data to national government agencies. Working with the Environment Agency (EA), Met. Office, Channel Coastal Observatory (CCO), Cornwall Council, Teignbridge District Council, Capgenimi and National Trust, we will build on previous research using digital communication, data networking and citizen science. Our recent project (WireWall) created a unique overtopping sensor that we will develop into a low-cost hazard monitoring system for long-term deployments using telemetry to transfer data. Another project (SWEEP) created a south west regional computer simulation that updates daily to forecast coastal hazard 3 days in advance. The CCO hosts both projects online alongside the Regional Coastal Monitoring Programmes (RCMP) across England. This project will incorporate our new hazard data into the SWEEP service through a new web-accessible, open source data staging web service, thus linking models and new monitoring to validate current hazard services. The new web service will expose existing, coastal, river and weather data, while the new system will include: 1) a novel wave overtopping sensor to measure water levels and waves just before they impact a sea wall in addition to the depth, volume and speed of the water as it overtops onto public access areas behind the sea defence; 2) cameras to validate wave conditions and confirm the occurrence of overtopping events; 3) laser measurements of the pre- and post-storm beach levels during an event; and 4) an international citizen science programme, CoastSnap, that monitors beach conditions over time through photographs. The system will use the UK's tide gauge network to trigger the measurement of potentially hazardous conditions when water levels reach the sea walls and return real-time alerts when flooding is detected. This information will allow validation of the SWEEP computer alert service. With the EA's flood forecast team we will use this information to refine their local hazard thresholds and to understand the uncertainty in local conditions at the sea wall sites due to their large (many km's) distance from national monitoring stations. The measured, visual and audio data will be used in an interactive coastal walk, and made accessible through an Augmented Reality (AR) phone application, available for IOS and Android devices. The AR walk will guide people to CoastSnap photo posts, encouraging participation in the RCMP beach monitoring. Promotion of the walk through the Tourist Information Centres and Twitter will raise community awareness of changing coastal hazards and shoreline management initiatives such as #floodaware and #CoastSafe. The team of oceanographers, engineers, data managers, a digital artist, a poet and a software developer will apply their expertise in different disciplines to significantly improve the accuracy and effectiveness of existing coastal hazard warning services. They will engage the public through an easily accessible phone app and participation in citizen science monitoring. Information will be archived at BODC and made available under the NERC Data Policy. This online catalogue is designed to be easily found by the Google dataset search engine and ensures our data are FAIR (Findable, Accessible, Interpretable and Re-usable). Keywords: Hazard monitoring; Coastal forecasting; Flood aware; Hazard warning