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- Role of shore platforms on coastal cliffs protection in Algarve (South Portugal): first approachPublication . Gabriel, Selma; Moura, Delminda; Ferreira, Óscar; Pacheco, André; Matias, Ana; Veiga-Pires, C.The complex interaction between morphogenetic processes acting on rocky coasts and substrate characteristics difficult the assessment of its evolution at different time scales. In opposition to other coastal environments such as beaches, where variations on substrate’s attributes are constrained to a few possibilities, rocky coasts expose substrates having large amount of variables, among them, lithology, mechanical and chemical strength, density and orientation of faults and joints and, rocks’ texture and structure (e.g., Trenhaile, 2003).
- Evolution of a relocated inlet migrating naturally along an open coastPublication . Popesso, Chiara; Pacheco, André; Ferreira, Óscar; Fontolan, GiorgioAncao Inlet is a small migrating inlet that was relocated in 1997 and has been monitored since then. In October 2015, it was about to conclude its third eastward migrating cycle since the 1940s. Morphological parameters and migration rates were correlated with oceanographic settings to evaluate the importance of different mechanisms in the evolutionary phases of the inlet. The migration trend is related to the dominant southwest sea conditions, inducing the alongshore sediment transport from west to east. The inherited features of the downdrift side area were also considered as rate of migration constraints. In this paper, we show how storm events, a constant longshore sediment supply from the west, and a lower downdrift barrier island volume control migration rates, noting that inlet efficiency is also strongly influenced by the reshaping of the barrier area.
- Flood vulnerability under sea level rise for a coastal community located in a backbarrier environment, PortugalPublication . Croteau, Raphaelle; Pacheco, André; Ferreira, ÓscarSea level rise will be a major threat to coastal communities within the next century due to the intensity and severity of the floods it can cause. A new methodology considering water infiltration, slope, and hydraulic connectivity was developed to assess the potential inundation extension associated with different total water level and sea level rise scenarios on sandy coasts. This methodology was applied for the current conditions as well as 2050 and 2100 scenarios of storm surge and high tide levels with return periods of 1 year and 100 years. The study area is Culatra village, located on the lagoon side of a barrier island in southern Portugal. The effects of shoreline evolution after the construction of a harbor and associated beach nourishment were also evaluated within the inundation scenarios. The results show that, within the study area, total water level variations caused by sea level rise have a greater influence on the inundation extension than shoreline retreat. The village appears to be safe for the current and 2050 total water level scenarios with a 1-year return period but would be highly affected by 100-year return periods, especially from 2050 onwards. This novel approach represents an improvement on more common flood mapping methods such as the bathtub approach and can be easily applied to other backbarrier environments under sea level rise or facing coastal erosion.
- The east coast of Algarve: a barrier island dominated coastPublication . Ferreira, Óscar; Matias, Ana; Pacheco, AndréThe east coast of the Algarve (Olhos de Agua - Guadiana) is a low sandy coast with a high diversity of environments, including a cliffed coast, sandy beaches, dune ridges, an estuary, artificial/antrophic sectors and a main, complex, central morphology: the Ria Formosa barrier islands and coastal lagoon system. The large majority of this coastal sector is within the Ria Formosa Natural Park and therefore protected by Nature conservation laws. Nevertheless, human activities contributed to some of the most important changes on coastal behaviour during the last decades, increasing processes complexity and incrementing furthermore the difficulties for the already demanding understanding of coastal evolution.
- Short-term sediment transport at a backbarrier beachPublication . Carrasco, Ana Rita; Ferreira, Óscar; Matias, Ana; Pacheco, André; Freire, PaulaThis article defines short-term (tidal cycle) sediment-transport patterns at a backbarrier beach based on detailed field studies. Fieldwork was planned to record nonstorm, spring tide conditions that enable the definition of background sediment dynamics at the study area. The experiment was set at two beach morphologies: beach face and sandbank. Current meters were deployed at both sites. Fluorescent tracer techniques were applied to determine rates and direction of transport. Topographic surveys and sediment sampling were undertaken. During the experiment, limited tracer displacement and small morphological changes occurred. The low magnitude changes are representative of predominant, low-energy hydrodynamic conditions. Sediment transport was primarily longshore orientated and dependent on the velocity of tidal currents. Tidal currents had the potential for sediment transport only during a short period of the tidal cycle and had higher velocities during ebb, which results in a net sediment transport orientated towards the nearby inlet. It is suggested that there is dependence on sediment transport rate at the study site and on the variability of tidal currents, which are greatly influenced by the distance to, and conditions of, the nearby Ancão Inlet.