A new in-situ coastal monitoring system is sending near real-time data to NERC EDS's British Oceanographic Data Centre, and being made publicly accessible online. The service takes in near-real time wave and water level data from existing national coastal monitoring networks, and provides a full dataset to validate and calibrate an operational wave, water-level and overtopping forecast system.

Near Real-Time Monitoring of Coastal Wave Overtopping

Photo of sea defences around a railway line, with scientific instruments circled and labelled.
Figure 1: The instrumented sea wall at Dawlish.

It is projected that global mean sea level could rise up to 1m this century with a strong regional pattern. With just under half this rise, 20% of England’s coastal defences could fail. Ambitious climate mitigation and adaptation plans may protect 400,000 – 500,000 people, but flood and coastal erosion risks cannot be fully eliminated. Building coastal climate resilience requires accurate wave overtopping prediction tools and nowcast information to prepare for, and respond to, coastal hazards.

Photo of waves overtopping sea defences.
Figure 2: Hazardous overtopping being measured and nowcast at Dawlish 7th December 2021.

The National Oceanography Centre with the University of Plymouth have installed a new monitoring system to measure wave overtopping conditions and concurrent beach level over a 1-year period in Dawlish, SW England (Figure 1). The system obtains in-situ measurements of the inland wave overtopping distribution across a public walkway and railway line (Figure 2), and issues near real-time overtopping data to the British Oceanographic Data Centre, one of the five NERC EDS data centres, making it publicly accessible online within 15 minutes of detection. This public web service takes in near-real time wave and water level data from existing national coastal monitoring networks (Figure 3), providing a full dataset to validate and calibrate an operational wave, water-level and overtopping forecast system.

Screenshot depicting dashboard panel with satellite imagery, graphs, and summary data.
Figure 3: The near real-time Coastal Hazard Explorer dashboard that integrates new and existing coastal monitoring data collected by different organisations.

Using these data, numerical forecasts have been refined, by incorporating recent beach levels (Figure 4), to reduce the uncertainty in the wave overtopping predictions due to seasonal variability in the beach level at the toe of the sea wall at Dawlish. Working with partners at Network Rail and the South West Regional Coastal Monitoring Programme, the data will allow the re-assessment of the coastal condition combinations that most frequently pose a hazard to the railway line and the public, to support the South West Rail Resilience Programme, and identify where site-specific modifications in operational predictions can be implemented to improve local hazard forecasts.

Graph depicting beach profile at Dawlish with most recent data compared against the average.
Figure 4: Beach profiles measured every low tide with the most recent being incorporated into the operational hazard forecast.