Learning with Nature: A Sand Dune System Case Study (Portugal)

he implantation of a submarine outfall pipe in 1995 for the cellulose pulp and paper companies Celbi and Soporcel, Portugal, led to some changes in the Leirosa sand dunes system. The use of heavy machinery and the close proximity of a breakwater aggravated the long-term problems of erosion in this coastal ecosystem. Sand accretion was the first step in the reconstruction of the Leirosa dunes. Subsequently, to stabilize the sand, we carried out revegetation, planting the grass Ammophila arenaria (L.) Link. In February 2001, after a particularly severe winter, most of the ocean-facing side of the Leirosa rehabilitated sand dune system was severely damaged. In spite of this problem, the monitoring plan to assess sand erosion and vegetation growth continued. In 2005, after balancing several alternatives, the Leirosa sand dunes were reconstructed with layers of geotextiles filled with sand. Once the sand containers were in place, this protective barrier was covered with sand and planted with A. arenaria, turning this area into an attractive and safe coastal dune system. In March 2006, some problems occurred, probably caused by poor sealing of the geotextiles layers, which led to parts of the three bottom layers breaking open. To stabilize and reinforce the sand dune in this specific weakened area, we are currently analysing the use of geotextile tubes. The attempts to promote the sustainable rehabilitation of a dune system and the implied problems related to its location on a particularly harsh Atlantic coast are discussed in the paper.