Geomorphology and evolution of the Miocene rock coast of the Algarve: a multi-tool approach

• Autor(a) principal: Stock, Jonas
• Data de Publicação: 2020
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.1/15359
• topic: Vulnerabilidade das arribas; Mecanismos de erosão; Liitologia; Formação carbonatada de lagos-portimão (lpcf); Detecção remota; Algarve (Portugal); Domínio/Área Científica::Ciências Naturais::Outras Ciências Naturais

Rocky coasts are widely distributed around the world (ca. 80% of the world coasts) and are subject to natural (physical, chemical, and biological) and anthropogenic pressures. The coastal evolution and erosional processes of the southern Algarve coast in Portugal have been previously studied; however, a precise analysis of the link between lithological characteristics and cliff vulnerability is lacking. Therefore, in this work we focus on facies variation and calcium carbonate (CaCO3) content, discontinuities, (faults, joints, and layering), and morphological features (karst, notches, and marine caves) present in the southern cliffs of the Algarve from Olhos de Água to Albandeira. We combine a variety of data, including those derived from traditional field-based rock assessments, lab-based CaCO3 content analysis, remote sensing (satellite and UAV image analysis) and photogrammetry. We find that the exposed carbonate rocks (mainly of Miocene age) at the southern Algarve are highly vulnerable to erosion. Additionally, we identify multiple key forcers: high vertical facies variation, intense karstification, multiple notches and marine caves. In addition, our lab analysis revealed differences in CaCO3 content for each lithofacies, resulting in alternating rock strength and leading to the formation of multiple structural notches into the cliff face. Surface features (Land Use Land Cover - LULC) were categorized using remote sensing data and photogrammetry. A classification of cliff vulnerability was developed based on a combination of these lithological and geomorphological factors. The sector Arrifes - Galé was classified as most vulnerable; Sector Galé - Armação de Pêra Bay was classified as least vulnerable in the study area.