Identifying Coastal Defence Schemes through Morphodynamic Numerical Simulations along the Northern Coast of Yucatan, Mexico

Ruiz-Martínez, G.; Mariño-Tapia, I.; Mendoza Baldwin, E.G.; Silva Casarín, R., and Enríquez Ortiz, C.E., 2016. Identifying coastal defence schemes through morphodynamic numerical simulations along the northern coast of Yucatan, Mexico. A beach segment on the northern coast of the Yucatan Peninsula, where sandy beaches have widespread erosion problems, was studied with morphodynamic numerical simulations to identify the most appropriate protection scheme for mitigating coastal erosion in the region. The numerical model Delft3D was used to model hydro-morphodynamic patterns. Three types of solution were simulated: (1) beach nourishment only, (2) beach nourishment and groynes (linear, Y- and T-shaped), and (3) beach nourishment and offshore breakwaters. Measured time series of wind, sea level, and shelf currents were fed into the numerical model. Morphodynamic simulations were validated by comparing the modelled volumetric changes with those observed from beach profiles. The morphodynamic evolution was evaluated using bottom depth contour maps, and a volumetric sand balance and sand flux analysis identified which scheme retained more sand in the littoral system. The protection scheme with linear groynes showed greater sand retention in the short term, but in the medium term, this solution enhanced beach erosion. The numerical simulations showed that beach nourishment performs better than linear groynes in the long term and have beneficial downdrift effects. Nevertheless, T groynes had the smallest loss of sand nourishment in the short and long terms, suggesting that this scheme could best retain sand, although exacerbating erosion in downdrift beaches. From a cost analysis perspective, T groynes show a lower maintenance cost than beach nourishment and linear groynes.