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1 November 2010 Working with Nature by Protecting Sand Dunes: Lessons Learned
José Antunes do Carmo, Catarina Schreck Reis, Helena Freitas
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Abstract

The construction of an underwater effluent damaged the continuity of the Leirosa sand dune system, which is located at south of Figueira da Foz, midway along the Portuguese coast. Considerable damage was caused to the dunes by the use of heavy machinery and by the erosion that occurred afterwards, since the rehabilitation began only 3 y latter. The existence of a breakwater less than 1 km to the north, also served to increase the erosion problems, causing the retention of large amounts of sand. As a consequence, sand accretion had to be the first step in reconstructing the Leirosa dunes. The rehabilitation of this system started in March 2000. After that, and to stabilize the sand, revegetation was carried out with transplants of the grass Ammophila arenaria (L.) Link, the most appropriate plant species used in these situations. The winter of 2000/2001 was particularly severe and in February 2001 most of the oceanic side of the Leirosa rehabilitated sand dune was destroyed during a storm that struck all of central Portugal, especially the coast. Between 2001 and 2009 several proposals for the rehabilitation of the Leirosa sand dunes were studied, including soft and hard engineering interventions. A solution adopted in 2005 consisted of dune reconstruction with layers of geotextiles filled with local sand (geocontainers). Due to problems probably caused by undermining of the bottom layers by local scour, another class of sand-filled containers (geotubes) was installed in early summer 2008 at the bottom of the existing structure as toe protection. Another round of revegetation was planned and implemented in May 2009. A new monitoring program was also implemented to locate, identify, quantify and characterize the existing and planted vegetation. Finally, and again using geotubes as the construction material, a complementary protection for the Leirosa sand dune system is described. It consists of a submerged breakwater (multifunctional artificial reef) that both protects the local coastline and enhances surfing possibilities. The main reef characteristics are presented.

José Antunes do Carmo, Catarina Schreck Reis, and Helena Freitas "Working with Nature by Protecting Sand Dunes: Lessons Learned," Journal of Coastal Research 26(6), 1068-1078, (1 November 2010). https://doi.org/10.2112/JCOASTRES-D-10-00022.1
Received: 8 February 2010; Accepted: 11 June 2010; Published: 1 November 2010
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