Sand bypassing and shoreline evolution near coastal structure, comparing analytical solution and XBeach numerical modelling

Abstract

The present study is aimed at comparing the numerical and analytical estimation of the shoreline near an idealized groyne structure. Moreover, the impact of sand bypassing on the accretion at the updrift coast calculated by analytical Pelnard solution is compared against the XBeach numerical model. The application of the XBeach model shows some promising results. Prior to bypassing, the resulting shoreline pattern from numerical (XBeach) model resembled the Pelnard model with slight differences. The circulation of wave driven-currents due to diffraction is responsible for the formation of a sand wedge at the downdrift side which cause the coastline to prograde. Despite the fact that the bypassing volume simulated by XBeach is smaller than the analytical solution, the shoreline pattern seems to reasonably follow the Pelnard model. Nevertheless, the use of process based numerical model like XBeach, has been shown to be useful in this type of research. This moreover proves the capability of XBeach model of predicting shoreline evolution and clarifying the mechanism of the natural bypassing process which cannot be achieved by analytical models.