Coastal erosion Portugal
The main morphological Portuguese coast types are sand shores, cliff coasts (the dominant type) and low-lying rock shores (least frequent). Estuaries and coastal lagoons are also important (1).
Average spring tidal range is 2.8 m. Wave energy is much higher on the west coast than on the south coast. No statistically significant changes in storminess along the Portuguese south coast have yet been found. Relative sea level rise near the Portuguese coast is now 2.1 mm/year; for 2100 a mean sea level rise of 47 cm (95% confidence interval between 19 and 75 cm) is projected compared with the current situation (1).
Shoreline retreat rates of more than 1 m/year are recorded for more than 50% of the sand shores, with locally maximum rates up to 5-10 m/year (2). Examples of areas under threat and facing serious problems are: Ofir, south of Espinho, south of Aveiro and Costa da Caparica on the west coast, and Quarteira-Vale do Lobo and Ria Formosa National Park on the south coast. Erosion of the Portuguese coastline became an important problem due to (1) lack of continuous and systematic monitoring of the coastline, (2) unarticulated management strategy by local, regional and national authorities, and (3) underestimation of erosion complexity.
Sediment starvation at coastal areas is amplified by mining activities at the river basins, estuaries and harbours, for navigational and construction purposes (3). Past and current sea level rise is a minor cause of shoreline retreat at sand shores, and probably only contributes 10-15% to actual shoreline retreat (4).
Due to a lack of clear rules and an integrated coastal management strategy, local problems used to be addressed with hard protection measures (mostly groins and seawalls) because of its immediate effectiveness, regardless of erosion problem transference to down drift areas. As a result, parts of the Portuguese coast became armoured whilst neighbouring down drift areas experienced ongoing severe shoreline retreat. Until the late 1980s, there was no integrated coastal management perspective in Portugal (5).
Current coastal protection policy in Portugal is no longer based on hard protection structures; most interventions are now dedicated to the maintenance or redesign of existing structures. Moreover, new structures are occasionally built to provide support to beach nourishment projects. Soft protection (beach and dune nourishments, sand fencing, access restriction, elevated footpaths, social awareness and education, housing removal) became a frequent management approach in Portugal in the 1990s. An integrated coastal management approach, however, is still uncommon (1).
The references below are cited in full in a separate map 'References'. Please click here if you are looking for the full references for Portugal.
- Ferreira and Matias (2013)
- Ferreira et al. (2008); Pedrosa and Freitas (2008), both in: Ferreira and Matias (2013)
- Veloso Gomes et al. (2006); Ferreira et al. (2008), both in: Ferreira and Matias (2013)
- Andrade et al. (2002); Ferreira et al. (2008), both in: Ferreira and Matias (2013)
- Veloso Gomes et al. (2006), in: Ferreira and Matias (2013)