Development of a 2D hydrodynamic model to assess the risk of flooding from wave overtopping and tidal inundation of a site in Co. Clare

A very significant storm event in January 2014 resulted in severe coastal erosion and flooding to Cloughaninchy beach in Co. Clare. A coastal flood and erosion risk management feasibility study of the site was subsequently... [ view full abstract ]

A very significant storm event in January 2014 resulted in severe coastal erosion and flooding to Cloughaninchy beach in Co. Clare. A coastal flood and erosion risk management feasibility study of the site was subsequently commissioned to understand the level of risk at the site and also to develop an engineering solution to mitigate the risk.

This paper details the construction, calibration and running of the 2D MIKE 21 hydrodynamic model that was developed as part of the study.

A 2km long embankment protects the site from tidal inundation but can be overtopped by near shore waves. The methodology used in estimating this risk was: (1) Estimation of near shore wave heights using a MIKE 21 SW model, (2) Estimation of wave overtopping discharges using the Eurotop manual. Given the significant length of embankment and its spatially varying crest level elevation, innovation in modelling was required to ensure the calculations were detailed and robust while not being overly burdensome, and (3) Inclusion of the wave overtopping discharges in the 2D model as source discharges points.

The results of the detailed modelling indicate that extensive areas of the site are at risk of flooding from wave overtopping. The results also suggest that a more simplified approach to estimating the wave overtopping flood risk at the site may not have been sufficient to highlight the risk.