Coastal overtopping forecast for South West England made available to the public.

Coastal processes scientists from the University of Plymouth have developed a new, more accurate way of forecasting wave overtopping hazards around the South West.

The Operational Wave and Water Level model (OWWL), developed at the University of Plymouth Coastal Processes Research Group (CPRG) as part of The South West Partnership for Environmental and Economic Prosperity (SWEEP) project, now provides insightful overtopping forecasts to the general public.

The model takes data from the Met Office and refines it to provide a high-resolution inshore wave forecast. In addition, the model uses detailed profiles of 183 beaches around the region, which – for the first time – allows the individual characteristics of an area to be taken into account. The profiles look at things like the slope of the beach, whether the beach is sand or gravel, or whether there are any sea defences in place.

With this information, the amount of water that is likely to overtop sea defences during a storm can be predicted up to three days ahead, which creates a highly accurate picture of when and where the sea might pose a hazard to people or property.

The team behind OWWL have been working with the Environment Agency and the Met Office to refine and test the model, which has now been made available to the general public online, and through daily Twitter and email alerts.

Gerd Masselink, Professor in Coastal Geomorphology at the University of Plymouth, explains more:

“Coastal flooding is normally considered to be the result of high tides and storm surge, but in the South West we have an important additional factor – wave run up. This occurs where really large waves hit costal structures or beaches, which pushes the water up and over the structures.

Having a good understanding of what the coastline looks like is crucial to being able to predict coastal flooding accurately. The OWWL model brings all the factors that causes coastal flooding together, and means forecasts are more accurate even at a really small scale.”

Dr. Kit Stokes, Coastal Processes Researcher at the University of Plymouth and one of the scientists who created OWWL, believes making the data available to the general public will help reduce the risks involved in coastal flooding incidents.

“The OWWL model generates daily forecasts which give a grading to the level of hazard posed by wave and water levels over the next three days – green equals low hazard, through to red, which means there is a potential hazard to pedestrians, property, and even transport near the coast.”

“We already provide this data to the Environment Agency to help inform their decision-making, but making this information available direct to the general public means more people will be aware of when it is unsafe to go near the coast, or when their property may get flooded or travel plans disrupted.”

Example of the OWWL overview forecast.

It is estimated coastal flooding costs £400mn to the UK economy each year. Providing more accurate forecasts of when and where coastal overtopping will occur will increase preparedness for storms, and also allow emergency services to focus on the areas most likely to be affected, which should reduce the social and economic costs of extreme storms.

OWWL is available on the Channel Coastal Observatory website where you can also sign up for the email alert service that provides detailed daily forecasts, or you can follow @Coastal_Hazards on Twitter for the overview forecast.

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