Long-term beach and coastal dune dynamics in response to natural and human-made factors.

This study took place in Playa Chachalacas, located in the central region of the Gulf of Mexico. The goal of this study was to understand the long-term consequences of modifying sediment dynamics through the combined effect of dune stabilization and the construction of breakwaters for shoreline protection. With aerial images from different years, the following items were analyzed: (a) stabilization of the mobile dune; (b) shoreline dynamics and changes at the river mouth, located down-drift from the dunefield; and (c) urbanization along the shoreline. Data show that the cover of grasses and shrubs increased rapidly. In some points, there was intense erosion along the shoreline and accretion in others. The breakwaters promoted accretion but exacerbated erosion down-drift, with notable changes in the inlet. Finally, urbanization has occurred at a fast rate, and mostly parallel to the shoreline. The results indicate that different factors affect sediment dynamics: (a) warm and wet climate promoted vegetation growth and sediment stabilization; (b) the breakwaters solved the erosion problem locally, but generated intense erosion down-drift; and (c) urbanization along the coast resulted in ecosystem loss and increased risks to flooding. Indeed, management and development plans for coastal environments need to consider the dynamic nature of the coastline.