Coastal ridge constructive processes at a multi‐decadal scale in Barreta Island (southern Portugal)

Abstract

Multiple ridges across prograding coasts may display variable geometries, commonly expressed through varying elevations. Changes in ridge elevation have been traditionally related to the occurrence of fluctuating progradation rates, which might, in turn, be driven by shifting environmental conditions.Here, we explore the geometry and growth mechanisms of multiple ridges, generated at Barreta Island (Ria Formosa, southern Portugal), as a consequence of the rapid progradation of the island over the last 70 years, following the artificial fixation of the downdrift Faro-Olhão inlet with jetties in 1955. The variability in the morphology of these features was analysed in combination with available wind and wave data, in order to better distinguish growth mechanisms and understand the main parameters determining the final geometry of the observed ridges.The results suggest that (1) most of the identified ridges fall in the beach ridge classification, as they have been mostly built by marine processes, and (2) the parameters derived from, or closely related to wave climate variability (e.g. progradation rates, storm occurrence) can jointly explain most of the observed morphological changes, while aeolian processes played a secondary role. Indeed, ridge geometry appears mainly controlled by progradation rates, with higher ridges associated with lower progradation rates. Progradation rate, in turn, is mostly related to longshore wave power, storminess, and the occurrence storm groups. Yet, the final configuration of ridges can also be affected by runup levels and onshore winds. Therefore, establishing the relation between ridge geometry and wave climate is not a straightforward task, because of the complex processes and interactions that control coastal morphodynamics.

Ecogeomorphic response of a coastal dune in southern Portugal regulated by extrinsic factors

“…However, the temporal scale of vertical dune growth is inversely related to shoreline progradation, meaning that the greater the progradation of the coast, the lower the elevation of the incipient dune. This pattern has been previously observed and conceptualised (Herrero et al, 2020;Moore et al, 2016;Psuty, 2004).…”

Evolutionary Trajectories of Coastal Sand Barriers along the West Portuguese Coast during the Holocene

“…Overall, the distribution of dune features suggests that foredunes dominate Segment C and that this dune type is associated with more stable or progradational coasts, e.g., [7,47]. On the other hand, transgressive dune fields are common features in Segments A and B.…”

Exploring Controls on Coastal Dune Growth Through a Simplified Model

“…and their multiple interactions (Brodie et al., 2019; Costas et al., 2023; Durán Vinent & Moore, 2015; Stallins & Corenblit, 2018). Their importance as ecosystem service providers has been widely acknowledged, motivating research on the different aspects controlling the evolution of these systems, such as vegetation cover (e.g., Talavera et al., 2022), dune shape, beach state (e.g., Garzon et al., 2022) and the processes controlling dynamics over distinct temporal scales, from event‐scale (e.g., Costas et al., 2020) to multi‐decadal (e.g., Herrero et al., 2020) changes. Coastal dunes display not only significant morphological variability alongshore (Houser, 2013; Houser et al., 2018; Moore et al., 2018), but also variable response depending on the shoreline trends at the adjacent beach (Brodie et al., 2019; Houser et al., 2022).…”