Quantitative Assessment Tool for Wind Effect on Wave Overtopping Seawalls

Climate change is expected to result in stronger and more frequent winds, storms and sea level rise, leading to more severe adverse effects on infrastructure such as flooding damage to buildings, power stations, railways and sea defences. The effects of this natural hazard have been frequently seen in recent flooding events in the UK and other countries worldwide. Over recent years, Royal HaskoningDHV has reported that wind effects on wave overtopping has become an increasing concern for the design of modern sea defences and the management of coastal flood risk. This threat can cause unexpected coastal flooding and pose additional flooding risks to coastal infrastructure, particularly in the UK as an island nation.
Currently, there is no reliable tool to quantify such risk. Present engineering practice is to either (i) ignore wind effects, which would put protected areas at risk, or (ii) include a large safety margin, which would significantly increase the cost of coastal defences unnecessarily. The safety margin method is also restricted to existing known coastal scenarios and cannot provide reliable assessment of the risks as climate changes. This is a clear knowledge gap that causes a growing concern for the ability to adequately and economically control coastal flood risk. The proposed project brings together leading experts from Manchester Metropolitan University, Royal HaskoningDHV, HR Wallingford, Environment Agency, EDF Energy and Torbay Council to address the concerns by developing a novel assessment tool to quantify wind effects on wave overtopping. Its aim is to translate the powerful two-fluid model from Manchester Metropolitan University into an engineering tool to quantify wind effects on wave overtopping, accounting for the effects of sea level rise. The objectives are to (a) adapt an advanced in-house two-fluid model for wind effects on wave overtopping, (b) validate the model rigorously against physical modelling tests undertaken at HR Wallingford, field data and real engineering application cases including ongoing or recently completed projects with the Environment Agency, SEPA and EDF Energy by Royal HaskoningDHV, (c) build a companion database to facilitate efficient assessment of the risk in design and management, and (d) enclose the tool and database in a simple user-friendly interface for efficient management and control of coastal flooding. Key activities also include visits to Heysham and Torbay for the collection of sea defence data and past event data where wind effects were significant on wave overtopping. The project partners will contribute to the supervision and steering of the project and provide real cases and data. This will be the first practical tool for accurately quantifying wind effects on wave overtopping. It will inform and improve current engineering practice, removing the need for large safety margins to account for wind effects in infrastructure design and assessment.
The main deliverables and outputs will be an assessment tool and a companion database. These tools will be used by Royal HaskoningDHV in the flood risk assessment, engineering design and coastal flood forecasting system, by EDF Energy to enhance the assessment of risks of coastal flooding to existing and new build power plants, by the Environment Agency for an improved coastal flood warning service and by Torbay Council for improving the flood risk management and supporting decisions relating to future development and emergency planning. The developed tool has the potential to become a vital design tool in assessing wind effects on wave overtopping, benefiting various organisations such as the Scottish Environment Protection Agency, Natural Resources Wales, Network Rail and Transport Scotland for the multiple purposes of planning strategic or investment decisions in management of coastal flooding risks to infrastructure. The project will last 14 months with a total cost of £159k at 80% FEC.

The overall objective is to develop a reliable tool to quantify wind effects on wave overtopping, which is able to account for the effects of anticipated sea level rise and stronger wave/wind actions arising resulting from climate change. The main deliverables and outputs will be an assessment tool and a companion database. This will enable the project partners to make a reliable assessment of wind effects on wave overtopping for improved service in coastal flood forecasting and warning systems, and to optimise the design of infrastructure that is vulnerable to wave overtopping. It will greatly improve the safety performance of existing and new build infrastructure such as sea defences, railways and power stations. The developed tool will fill an important knowledge gap in coastal and maritime engineering practice. It has the potential to become a vital design tool in assessing wind effects on wave overtopping, benefiting many organisations such as the Environment Agency, Scottish Environment Protection Agency, Natural Resources Wales, Network Rail, Transport Scotland and local councils for the multiple purposes of safely planning strategic or investment decisions and effective management of coastal flood risks.