The impact of rising sea level on the flood hazard from sea defence overtopping means new coastal schemes need to remain resistant to changing waves and water levels over the next 100 years. The design of new sea defences, and the setting of tolerable hazard thresholds, requires site-specific information of wave overtopping during storms of varying severity, which are combined with future projections in sea level. By converting an existing wave measurement technology into an overtopping monitoring system "WireWall", field observations of wave-by-wave overtopping velocity and volumes have been made at our case study site Crosby, in the North West of England. The new system has collect observations that will now provide site-specific data to:
- perform calibration of overtopping tools, e.g., EurOtop;
- perform validation of flood forecasting systems and overtopping models; and,
- develop site-specific safety tolerances to inform flood risk response plans.
Recent advances in technology mean existing wave height sensors can now measure at the high frequencies (a few 100 Hz) required to obtain overtopping data, making this the ideal time to initiate a step-change in coastal hazard monitoring capabilities. At Crosby a business case for a new sea wall is underway. Deployments at this site have collected measurements that will provide the local authority with the site-specific data and calibrated overtopping tools that they need to design a new, cost-effective and future-proofed sea wall. The development of WireWall and its deployment at Crosby during winter 2018/2019 was the first step towards the development of an overtopping monitoring system that could ultimately be integrated into new coastal schemes as part of the Regional Coastal Monitoring Programmes. Such data could enable long-term trend analysis of the changing flood hazard as a consequence of climate change and sea level rise at the coast.
In order to engage with the local community and coastal practitioners, a portable demonstration model of the WireWall field rig has been constructed in Lego. This has proven to be a great success at business and outreach events enabling the research team to showcase their new measurement technology and raise awareness of coastal hazards, coastal management and show how new advances in research can inform management decisions. The Lego figures from the demo also form a key feature of our twitter feed @WireWall_NOC, which has 158 followers including local community groups, academics, government and industry. Our active engagement has initiated an innovative approach to knowledge exchange, which now forms the foundation on which the communication strategy for the new coastal scheme can build on.