Inland beach migration ("beach erosion") and the coastal zone management (The experience of the northwest coastal zone of Portugal)

1. The fast inland beach migration (beach erosion) and the cliff retreat in the coastal zone of Northwest Portugal create strong difficulties to the real inception of any coastal zone management plan. As the dynamics are controlled by processes of natural global change, negative impacts for the coastal landscape (threatening followed by destruction) and for the natural resources cannot be avoided, but just temporarily mitigated. The migration is very sensitive where the coastal border shows washovers that every year widen and extend their fans inland, especially after storms, producing cliff retreats of several meters. Blowouts develop in the foredunes frequently due to an initial anthropic trampling. Beaches loose sand putting into evidence the bedrock whose outcrops extend every year. Trying to thwart the negative impact of those natural dynamics, engineering defence structures (groynes, revetments, and ripraps) have been built in areas of towns, leisure sites, etc. However, all evidences in the segments where they have been built, points to short-term efficiency-breakdown and partial destruction, besides an increasing of downdrift erosion. 2. The purpose of the research is to understand how the inland beach migration and the associated accelerated cliff retreat can produce difficulties like a poorly successful management plan or the inexisting realisation in the field. 3. The research work is based on field work guided by the interpretation of aerial photographs taken in different years, and completed by sedimentological analysis, geochronological datings, geomorphological mapping and geological surveys (cross sections, drilling), in order to understand the geological setting of the coastal zone and its recent changes (neotectonics). 4. Options to be undertaken: To defend just what can be justified by strong economical interests, including the conservation of coastal landscapes To plan gradual retreat, including the total stop to urban or leisure centres to extend further parallel to the sea To allow the natural evolution of coastal segments; this will avoid that small governmental budget for coastal defence be thrown overboard. Any option undertaken should be based on scientific research data. In Portugal generally, decision-makers forget this when they draw-up coastal management plans or risk maps. Under the pressure of several political and financial lobbies the urgent exploitation of natural resources increases. The reports are filed by the bureaucracy or seem to be a mission impossible, because scientifically poorly based. However, they must become a challenge of the 21st century. How? For a country like Portugal, which option will be the challenge?