Morphodynamics of the Cacela inlet and ebb-tidal delta based on Sentinel 2 images

• Autor(a) principal: Guélard-Ancilotti, Emile
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.1/18184
• topic: Inlet; Ebb-tidal delta; Morphodynamics; Shoals; Ebb channel; Cacela-cabanas system; Hydrodynamics; Sentinel-2; Domínio/Área Científica::Ciências Naturais::Outras Ciências Naturais

The main objective of this master thesis was to investigate and comprehend the short-term morphologic evolution of Cacela Inlet and ebb-tidal delta, based on Sentinel-2 satellite imagery from September 2015 to September 2020. The different observations made on Cacela inlet and ebb-tidal delta were analyzed and possibly related with computed waves data from SIMAR numerical model in order to observe the influence of prevailing hydrodynamic conditions that can act on it. Through the analysis of its barriers, inlet and ebb tidal delta features morphology and morphodynamics, this study produced a first morphological characterization of the system. Indeed, regarding its general observed morphology, it was characterized as a system with mixed energy influences showing characteristic morphological features produced by both tidal currents (e.g., almost constant well developed margin linear bars) and wave forcing (e.g., swash bars and ebb-tidal delta asymmetry). Moreover, the inlet evolution was related to the barriers morphodynamics, which was strongly influenced by the ebb delta shoals/channel behaviors. Those barriers showed quite unbalanced evolutions due to the shoals preferential welding to the downdrift barrier, and to an updrift barrier more exposed to the waves. Those processes were mostly governed by the combination of eastward longshore drift and mixed waves origins influence. However, the large and unusual morphological variability observed at Cacela ebb tidal delta was hardly related to wave activity, except for some large storm events. Among these, the Emma storm stands out as it was considered to have initiated or aided the present inlet position stability by straightening and shifting the unstable arcuate channel at the center of Cacela Inlet. This stability contrasts with Lacém Inlet’s (previous inlet separating Cabanas Island from Cacela Peninsula until its artificial closure and relocation through the opening of Cacela Inlet in 2011) that showed high (downdrift) migration, thus indicating successful inlet management.