A Critical Analysis of the Wind Generated Effect on the Rate of Overtopping on the Hinkley Point C Sea Wall Through the use of Physical Modelling

Abstract

It is widely observed that storms and the associated extremes of wind and wave conditions result in dramatic cases of sea defence overtopping. This phenomenon highlights a gap in knowledge that the industry standard EurOtop method for calculating overtopping volumes does not account for the effect of wind. This study aims to outline a generalised relationship between increasing onshore wind speed during storm events and the resulting volume of sea defence overtopping coupled with spatial distribution of the overtopped water. With design criteria being site- specific, this physical model experiment will recreate the conditions at Hinkley Point C to determine what extent the seawall has been designed and constructed to cope with these climatic and meteorological effects. Three water levels will be tested to identify overtopping rates and to establish the extent of hazard zones behind the coastal structure. This paper provides evidence that there is a strong exponential relationship between onshore wind speed and an increase in overtopping volume. The effect of wind increases the overtopping rate by up to 20 times at scale than that of no onshore wind. This effect of wind is a critical factor in design but not well researched within the industry. With this construction project at the central hub of the industry’s scrutiny, the necessity to understand and quantify the effects of overtopping due to the associated dangers is crucial.