Water level modeling on micro-tidal beach, application of several wave breaking approaches
Résumé
Beaches of Bocagrande peninsula, in the South-West of the Colombian old bastioned town of Cartagena de Indias are of great interest for coastal floods studies. The urban and touristic activities of the district suffer regularly substantial floods, due to the very low-lying topography of the whole sandy bar. In today's sea level rise context, concerns about flood's extents and frequencies are locally growing. The site benefits from high precision topographic data (LIDAR), a ΔGPS topo-bathymetric evolution monitoring and a video observation system (HORUS) used to detect high water level during storms and strong swell events. Those assets make Bocagrande an appropriate site to realize a crossed study of several wave breaking models and compare the different simulated water levels with observations. From nested-scale simulations of wave propagation with WW3 and SWAN models, several methods aiming at reproducing the wave breaking phenomenon are tested. Parametric formula (Stockdon/ Holman), boussinesq model (pCOULWAVE), Non-Linear Shallow Water model (SWASH) and Smooth Particule Hydrodynamics approach (SPhysics) are applied on Bocagrande's beaches' characteristics to derive water levels at the coast. The comparison between observations and simulations shows variable results. While the most accurate simulations have a vertical precision of 0.10 to 0.20 m, others shows a link between beach steepness and the increase in error values. Moreover the water levels calculations underline the importance of beach profile morphology on the highest reached levels and on floods' extents.