Coastal dune stabiIization using geotextile tubes at Las Coloradas

摘要

Beaches and coastal dunes at Las Coloradas, Mexico, were severely affected after Hurricane Wilma stormed through the northern coast of the Yucatan Peninsula in October 2005. Dune destruction connected open sea with lagoon systems at some points, with disastrous consequences for the local ecosystems. The regional economy depends on salt extraction, and therefore interactions between open sea water and salt-production lagoons brought enormous economical losses to the Las Coloradas community. To repair the damage caused by the hurricane, emergency actions were taken. Beaches were filled to close the breakages between sea and salt-production lagoons. However, those actions did not assure a reliable long-term solution. The probabilities of such meteorological events to recur in this area are high. Therefore, it was imperative to build a natural structure to fully guarantee entirely dune stabilization, avoiding littoral drift alterations. A reinforced dune using geotextile tubes covered with sand for revegetation was built along 2.5km next to the coast during 2006, and increased to 3.9km by September 2007. The structure protected the salt-production lagoons without affecting coastal processes in the area and natural evolution of surrounding beaches. Dune stability, beach performance, and littoral processes have been continuously monitored since reconstruction started in May 2006. This paper summarizes design criteria, some building process details, and results obtained up to September 2007. A comparison of the structure performance and beach evolution under 2 different wave conditions is also described. It is concluded that the implemented structure is performing as expected and the dune stabilized shows no evident risk of collapsing under extreme climatological events. However, some critical areas where the geotextile tube is fully exposed to wave action must be permanently monitored. The technology described herein represents a reliable solution; however, it is expected that much experience will be gained to improve, in the near future, the use of geotextile tubes as elements for dune reinforcement.