Beach Resilience to Coastal Structures on a Natural Beach

Beach resilience plays an important role on reducing coastal risk associated to either natural or human induced perturbations affecting the coast. Field experiments were conducted in order to investigate beach resilience in Sisal, Yucatán. Both impermeable and permeable 14-m groins were designed to asses the impact of coastal structures on the beach morphology during a 24-hour period. The experiments were conducted in the spring of 2015 and 2016, allowing the assessment of both structures under similar forcing conditions. Intense sea breeze events (W>12 m/s) generated high-angle short-waves, driving alongshore transport in the swash zone. Wind, waves, tides, and currents were measured concurrently and are correlated with beach morphology evolution data derived from intense monitoring conducted during the structure deployment. The impermeable structure induced a significant beach accretion (>60 m3/day) in the updrift side of the structure causing a tremendous impact downdrift. On the other hand, the permeable groin induced a smaller but still significant accretion (40 m3/day), allowing sediment bypass throughout the structure. Furthermore, the beach surveying continued after structures removal in order to estimate the beach recovery capability. Field observations show that the impact of the structure on the morphology is negligible six days after structure removal for the impermeable groin and only one day for the permeable structure. The latter suggests the high beach resilience of the study area. We acknowledge field support provided by researchers and students at the LIPC-UNAM. Financial support was provided by CONACYT (Projects LN271544 and Cátedras 1146), DGAPA-UNAM (PAPIIT-IN107315) and Grupo BARI.