Morphodynamic Evolution and Sediment Transport Processes of Cancun Beach

Large-scale construction of tourist infrastructure on beaches around the world is consistently linked to unwanted morphological changes that lead to coastal erosion. Dune destruction, alteration of sediment sources, and the rigidisation of the coastal system are known to be the main causes of erosive behaviour on many tourist beaches. To plan sound shoreline management strategies, detailed understanding of the sediment transport processes is necessary. The present contribution focuses on the main sediment transport processes that take place at Cancun, Mexico, a large (12 km) and highly developed tourist beach. High-resolution quarterly beach profile monitoring from September 2007 to June 2009 is used to calculate volumetric changes that are reasonably well explained by the spatial patterns of modelled sediment transport potential. This parameter was calculated using the wave propagation model WAPO of Universidad Nacional Autonoma de Mexico, which explicitly solves diffraction and reflection processes that are particularly important in systems with pronounced rocky headlands, such as the northern and southern ends of Cancun beach. Results show a dominance of northward longshore transport in most of the system, and an important transport divergence with consistent southward transport at the southern end. Cross-shore transport seems to dominate the middle-north section of the beach. This behaviour is consistent with recent advances in the understanding of wave circulation in embayed beaches. The method used here is considered a good approximation of sediment transport patterns when local (surf zone) morpho- and hydrodynamic data are absent or difficult to acquire.