Empirical parameterization of wave runup and dune erosion during storm conditions on a natural macrotidal beach

International audienceAn experimental study based on field measurements for runup parameterization was conducted on a high energy macrotidal beach located on North Brittany (Vougot Beach). The approach was based on morphological and hydrodynamic high frequency monitoring collected between 2008 and 2013. The aim was to quantify in-situ environmental conditions and dimensional swash parameters for the best calibration of Battjes (1971) runup formula. In addition, an empirical equation based on observed tidal water level and offshore wave height was produced to estimate extreme water levels defined as the sum of (i) astronomic tide, (ii) storm surge, and (iii) vertical wave runup. A good correlation between this empirical equation (1.01Hmoξo) and field runup measurements (Rmax) was obtained (R2 85%). The goodness of fit given by the RMSE was about 0.29 m. Extreme water levels were then used to explain dune erosion processes that occured during the winter storms 2013-2014. A good relationship was noted between dune erosion and high water levels when they exceed the dune foot elevation