Seasonal and episodic variability in the morphodynamics of an ephemeral inlet, Zinkwazi Estuary, South Africa

The inlet dynamics of estuary and lake systems with ephemeral inlets have been little studied compared to systems with semi-permanent tidal inlets. In this article, the authors have documented the meso-scale dynamics of a barrier and its associated ephemeral inlet. The inlet is typically open during...

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Bibliographic Details
Published in:Journal of coastal research 2013-01, Vol.1 (65), p.446-446
Main Authors: Bond, J, Green, A N, Cooper, J A G, Humphries, M S
Format: Article
Language:English
Subjects:
Barriers
Channels
Coasts
Deltas
Dynamical systems
Dynamics
Estuaries
Inlets
Low flow
Morphology
Oceanography
Rainy season
Sand
Seasons
Tidal inlets
Tidal prism
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Summary:The inlet dynamics of estuary and lake systems with ephemeral inlets have been little studied compared to systems with semi-permanent tidal inlets. In this article, the authors have documented the meso-scale dynamics of a barrier and its associated ephemeral inlet. The inlet is typically open during the rainy season and experiences closure during winter low flow periods. It does not migrate. The inlet is formed by fluvial overtopping of the barrier and when active, forms a small delta seaward of the channel and a small flood tide delta in the back-barrier. The tidal prism is insufficient to maintain the inlet and it is quickly sealed through wave-reworking of sand from the ephemeral delta when fluvial discharge diminishes. During a large ocean swell event coupled with abnormally high tides in 2007, a departure from this seasonal behaviour occurred. The barrier migrated 100 m landwards and formed a gently seaward dipping sand sheet. Whereas the barrier had previously been narrow, it was widened by 80 m and rose 1.5 m in elevation.
ISSN:0749-0208
1551-5036
DOI:10.2112/SI65-076