Sediment dynamics of a divergent bay-marsh complex
Citable URI
https://hdl.handle.net/1912/26511As published
https://doi.org/10.1007/s12237-020-00855-5DOI
10.1007/s12237-020-00855-5Keyword
Salt marsh; Geomorphic trajectory; Sediment fluxAbstract
Bay–marsh systems, composed of an embayment surrounded by fringing marsh incised by tidal channels, are widely distributed coastal environments. External sediment availability, marsh-edge erosion, and sea-level rise acting on such bay–marsh complexes may drive diverse sediment-flux regimes. These factors reinforce the ephemeral and dynamic nature of fringing marshes: material released by marsh-edge erosion becomes part of a bay–marsh exchange that fuels the geomorphic evolution of the coupled system. The dynamics of this sediment exchange determine the balance among seaward export, deposition on the embayment seabed, flux into tidal channels, and import to the marsh platform. In this work, we investigate the sediment dynamics of a transgressive bay–marsh complex and link them to larger-scale considerations of its geomorphic trajectory. Grand Bay, Alabama/Mississippi, is a shallow microtidal embayment surrounded by salt marshes with lateral erosion rates of up to 5 m year−1. We collected 6 months of oceanographic data at four moorings within Grand Bay and its tidal channels to assess hydrographic conditions and net sediment-flux patterns and augmented the observations with numerical modeling. The observations imply a divergent sedimentary system in which a majority of the suspended sediment is exported seaward, while a smaller fraction is imported landward via tidal channels, assisting in vertical marsh-plain accumulation, maintenance of channel and intertidal-flat morphologies, and landward transgression. These results describe a dynamic system that is responsive to episodic atmospheric forcing in the absence of a strong tidal signal and the presence of severe lateral marsh loss.
Description
Author Posting. © Springer Nature , 2020. This article is posted here by permission of Springer Nature for personal use, not for redistribution. The definitive version was published in Nowacki, D. J., & Ganju, N. K. Sediment dynamics of a divergent bay-marsh complex. Estuaries and Coasts, (2020), doi:10.1007/s12237-020-00855-5.
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Suggested Citation
Nowacki, D. J., & Ganju, N. K. (2020). Sediment dynamics of a divergent bay-marsh complex. Estuaries and Coasts.Related items
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