Evolution of a Shallow Water Wave-Dominated Shipwreck Site: Fougueux (1805), Gulf of Cadiz

Abstract

The evolution of the shallow water wave-dominated Fougueux wreck site in theGulf of Cadiz was investigated through repeat bathymetric surveys, wave- andcurrent-velocity field measurements, and numerical modeling. This multidisci-plinary approach was used to understand the relationships between scouring,morphodynamic change, and hydrodynamic forcing. Field experiments andnumerical models indicate that wave processes dominate site evolution. Nu-merical model outputs indicate current velocity, bed shear stress, orbital veloc-ity, and specially wave fraction breaking (with an increase of 45% and 135%for weak and significant storm conditions, respectively) are all amplified at thesite. Scour pits 0.8 m depth inshore and 0.4 m depth offshore of the wreckare developed in response to hydrodynamic forcing. Time-lapse bathymetricsurveys quantify seasonal geomorphological change at the Fougueux. Up to 1.2m of sediment is deposited and 0.7 m of sediment eroded in response to sea-sonal wave climate variation (an increase of 0.5 m for mean significant waveheight, 0.9 m for significant wave height corresponding to 99% of nonex-ceedance probability, and 0.4 m·s−1 for mean near-bed orbital velocity duringwinter conditions). A two-dimensional scour model reproduces observed sea-sonal scour changes. Results have direct applications at all stages of a wrecksite investigation