Morphology and sedimentology of a microtidal beach with beachrocks: Vatera,Lesbos, NE Mediterranean |
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| Authors: | MI Vousdoukas AF Velegrakis TV Karambas |
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| Institution: | 1. ENEA, UTMEA, Casaccia, Roma, Italy;2. Department of Earth Sciences, “Sapienza” University, Rome, Italy;3. MARUM, University of Bremen & ZMT, Tropical Marine Ecology Center, Bremen, Germany;4. Lamont-Doherty Earth Observatory, Columbia University, NY, USA;5. Department of Earth Sciences, Environment and Resources, “Federico II” University, Napoli, Italy;6. Istituto Nazionale di Geofisisica e Vulcanologia, Roma, Italy;7. Department of Mathematics and Geosciences, University of Trieste, Italy;8. Department of Earth and Geoenvironmental Sciences, “Aldo Moro” University, Bari, Italy;9. Department of Chemical and Geological Sciences, University of Cagliari, Italy;10. Department of Phisics and Earth Sciences, University of Messina, Italy;11. Department of Biological, Geological and Environmental Sciences, University of Catania, Italy;12. CNR, IRPI, Bari, Italy;13. MedSharks, Roma, Italy;14. Department of Biological and Environmental Sciences and Technologies, University of Salento, Lecce, Italy;15. Aix-Marseille Université, CEREGE CNRS-IRD UMR 34, Europole de l''Arbois Aix-en-Provence, France;1. Dr., Department of Physical and Environmental Geography, School of Geology, Aristotle University of Thessaloniki, 54124, Thessaloniki, Hellas;2. Dr., Institute of Materials Science, N.C.S.R. DEMOKRITOS, 15310 Agia Paraskevi Attikis, Hellas;3. MSc, Department of Geology, School of Geology, Aristotle University of Thessaloniki, 54124, Thessaloniki, Hellas;4. Dr., Centre Europen de Recherches et denseignement des Gosciences de lEnvironnement (CEREGE, UMR 6635 CNRS), Europle Mditerranen de lArbois BP 80 13545 Aix-en-Provence CEDEX 04, France;1. CIMA/FCT, University of Algarve, Faro, Portugal;2. School of Geography and Environmental Sciences, Ulster University, Coleraine, Northern Ireland, UK;3. Geological Sciences, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Durban, South Africa |
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| Abstract: | The present contribution considers the dynamics of beaches occupied by outcropping/buried beachrocks, i.e. hard coastal formations consisting of beach material lithified by in situ precipitated carbonate cements. The dynamics of a Greek microtidal beach with beachrocks (Vatera, Lesbos) are examined through the collection and analysis of morphological and sedimentary field data, a 2-D nearshore hydrodynamic model and a specially constructed 1-D morphodynamic model. The results showed that the beachrock-occupied part of the beach is characterised by distinctive morphodynamics as: (i) its beachface is associated with large slopes; (ii) there is a good spatial correlation between the sub-aerial and shallow submerged mean beach profile and the buried/outcropping upper beachrock surface; and (iii) the seaward margins of the submerged beachrock outcrops are always associated with a ‘scour step’ i.e. a submerged cliff. The results also showed that beachrock outcrops can bias cross-shore sediment exchanges by impeding onshore transport due to the presence of the scour step. In this sense, beachrock outcrops may be considered as offshore transport ‘conduits’ for the beach sediments. A conceptual model of beach sediment transport, based on the field data and the hydrodynamic modelling is proposed. According to this model, fresh beach material from adjacent terrestrial sources is transported alongshore, towards the central part of the embayment, where a littoral transport convergence zone occurs under most wave conditions. There, the laterally supplied sediments are lost offshore. |
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