Wave-angle control of delta evolution


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dc.contributor.author Ashton, Andrew D.
dc.contributor.author Giosan, Liviu
dc.date.accessioned 2011-08-02T13:20:12Z
dc.date.available 2012-01-07T09:30:34Z
dc.date.issued 2011-07-07
dc.identifier.citation Geophysical Research Letters 38 (2011): L13405 en_US
dc.identifier.uri http://hdl.handle.net/1912/4736
dc.description Author Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 38 (2011): L13405, doi:10.1029/2011GL047630. en_US
dc.description.abstract Wave-influenced deltas, with large-scale arcuate shapes and demarcated beach ridge complexes, often display an asymmetrical form about their river channel. Here, we use a numerical model to demonstrate that the angles from which waves approach a delta can have a first-order influence upon its plan-view morphologic evolution and sedimentary architecture. The directional spread of incoming waves plays a dominant role over fluvial sediment discharge in controlling the width of an active delta lobe, which in turn affects the characteristic rates of delta progradation. Oblique wave approach (and a consequent net alongshore sediment transport) can lead to the development of morphologic asymmetry about the river in a delta's plan-view form. This plan-form asymmetry can include the development of discrete breaks in shoreline orientation and the appearance of self-organized features arising from shoreline instability along the downdrift delta flank, such as spits and migrating shoreline sand waves—features observed on natural deltas. Somewhat surprisingly, waves approaching preferentially from one direction tend to increase sediment deposition updrift of the river. This ‘morphodynamic groin effect’ occurs when the delta's plan-form aspect ratio is sufficiently large such that the orientation of the shoreline on the downdrift flank is rotated past the angle of maximum alongshore sediment transport, resulting in preferential redirection of fluvial sediment updrift of the river mouth. en_US
dc.description.sponsorship This research was supported by NSF grants EAR‐0952146 and OCE‐0623766, the Exxon‐Mobil Upstream Research Company, and the WHOI‐USGS postdoctoral fellowship. en_US
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dc.language.iso en_US en_US
dc.publisher American Geophysical Union en_US
dc.relation.uri http://dx.doi.org/10.1029/2011GL047630
dc.subject Depositional asymmetry en_US
dc.subject Large-scale coastal evolution en_US
dc.subject Numerical modeling en_US
dc.subject Plan-view delta evolution en_US
dc.title Wave-angle control of delta evolution en_US
dc.type Article en_US
dc.identifier.doi 10.1029/2011GL047630

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