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Sand bypass and updrift beach evolution after jetty construction at an ebb-tidal delta
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Orientador(es)
Resumo(s)
The evolution of an ebb-tidal delta (Guadiana, South Portugal) and its updrift beach after jetty construction
(in 1972e1974) is analysed based on 24 ortho-rectified aerial photographs (1940e2012) and 13
bathymetric maps (1969e2014). The objectives are to evaluate the re-establishment of the sand
bypassing process and if the disruption of the historical delta may affect the updrift beach evolution.
Post-jetty progradation of the updrift beach resulted from two large accretion events. The second
(largest) event (110 m progradation in 1985e1994) was due to beach attachment of a shoal produced by
the erosion of a broad shallow area relict of the historical delta. The reworking of sand from this relict
area also enables the individualisation of a lateral updrift bar simultaneously with the new ebb shoal
proper formation. Both morphological features were close to (volume) equilibrium in 1995, indicating
that most of the sand was transported towards the downdrift side of the inlet at that time. This study
shows that erosion of the historical delta may enhance significantly the updrift shoreline progradation
and may promote the re-establishment of sand bypassing after jetty construction.
Descrição
Palavras-chave
Mixed-energy tidal inlet Guadiana Ebb shoal Lateral bar Morphology Shoal attachment
Contexto Educativo
Citação
Editora
Elsevier