Shoreline Retraction and the Opening of a New Inlet: Implications on Estuarine Processes
The dynamics of estuarine systems is sensitive to changes in its forcing conditions, including the morphology of its inlets. Coastline retraction, which may be induced by climate change, can result in modifications of estuarine inlet morphology. Through the use of a validated numerical model, we evaluate the effects of the opening of a new inlet on a tide-dominated estuary (Caravelas estuary, Brazil). During the last decades, shoreline retraction and the breach of an internal drainage channel led to the formation of a new inlet that became the main estuarine channel. The morphological changes of the estuary resulted in changes to its estuarine processes, including the general increase in the influence of the tide on the system and changes to its asymmetry. Internal channels that interconnect adjacent estuaries present great changes caused by the morphological alterations, not only in the magnitude of the processes but also in the resulting net transport direction. The increase in the water flow caused by the opening of the channel leads to an increase in the amount of water and materials carried toward the estuary. The changes presented here for the Caravelas estuarine system and the possible implications for the functioning of such systems demonstrate the importance of evaluating morphological aspects in relation to their use and management.
KeywordsEstuarine processes Inlets Morphological change Caravelas estuary
This study was funded by Fundação de Apoio a Pesquisa do Estado de São Paulo through the project “Avaliação da disponibilidade e enriquecimento antrópico de metais, arsênio e hidrocarbonetos em sedimentos marinhos no estuário de Caravelas (Sul da Bahia)” (FAPESP No. 2013/00102-8) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) through the Pro-Abrolhos Project (Institutos do Milênio—CNPq 420219/2005-6) and project “Avaliação da qualidade ambiental no estuário do rio Caravelas, BA, nos últimos 150 anos, segundo uma visão de multi-indicadores” (CNPq 477235/2009-3). Eduardo Siegle, Silvia H.M. Sousa, Rubens C.L. Figueira and Carlos A.F. Schettini are CNPq research fellows. The applied numerical model is the Delft 3D open source version, available from Deltares (https://oss.deltares.nl/web/delft3d).
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