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JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 110,
F02013,
doi:10.1029/2004JF000265,
2005
Fluvial and marine controls on combined subaerial and subaqueous delta progradation: Morphodynamic modeling of compound-clinoform
development
John B. Swenson
Department of Geological Sciences and Large Lakes Observatory, University of Minnesota, Duluth, Duluth, Minnesota, USA Saint Anthony Falls Laboratory, University of Minnesota, Minneapolis, Minnesota, USA
Chris Paola
Saint Anthony Falls Laboratory, University of Minnesota, Minneapolis, Minnesota, USA Department of Geology and Geophysics, University of Minnesota, Minneapolis, Minnesota, USA
Lincoln Pratson
Earth and Ocean Sciences, Duke University, Durham, North Carolina, USA
Vaughan R. Voller
Saint Anthony Falls Laboratory, University of Minnesota, Minneapolis, Minnesota, USA Department of Civil Engineering, University of Minnesota, Minneapolis, Minneosta, USA
A. Brad Murray
Earth and Ocean Sciences, Duke University, Durham, North Carolina, USA
Abstract
Fluviodeltaic systems commonly display a compound-clinoform geometry that consists of a subaerial/subaqueous delta couplet.
The extent of subaqueous delta development varies significantly and, in modern systems, is a function of fluvial input and
basin hydrodynamics. We present a model of fluviodeltaic progradation in which the repeated occurrence of characteristic terrestrial
floods and large coastal storms drives fluvial and shallow marine morphodynamics, respectively. We couple fluvial and shallow
marine sediment dynamics via the surf zone, which we collapse to a shock condition and treat as a moving boundary. With steady
sediment supply and sea level and simple basin geometry, our model naturally develops prograding deltas with compound-clinoform
geometries. The subaerial delta grows via fluvial aggradation and shoreface progradation, whereas the subaqueous delta expands
through foreset progradation, with only minor topset aggradation. The interplay of fluvial input with the wave/current field
controls the basic partitioning of sediment between subaerial and subaqueous deltas and, by extension, the compound-clinoform
geometry. Increasing the frequency or magnitude of coastal storms, decreasing flood frequency or discharge, and reducing grain
size all increase the fraction of sediment delivered to the shallow marine environment and the extent of subaqueous delta
progradation relative to subaerial delta development. Our model, which emphasizes the intrinsic coupling of fluvial and shallow
marine sediment dynamics and downplays the importance of allogenic fluctuations, can explain many of the first-order morphologic
features of natural delta systems, including significant lateral separation of the shoreline and clinoform rollover and differing
rates of subaerial and subaqueous delta progradation.
Received 14
November
2004;
accepted 28
March
2005;
published 10
June
2005.
Keywords: clinoform;
subaqueous delta;
morphodynamic modeling.
Index Terms: 3020 Marine Geology and Geophysics: Littoral processes; 3022 Marine Geology and Geophysics: Marine sediments: processes and transport; 3225 Mathematical Geophysics: Numerical approximations and analysis (4260); 4219 Oceanography: General: Continental shelf and slope processes (3002); 4558 Oceanography: Physical: Sediment transport (1862).
Read Full Article (file size: 1261243 bytes) Cited by
Citation: Swenson, J. B., C. Paola, L. Pratson, V. R. Voller, and A. B. Murray
(2005),
Fluvial and marine controls on combined subaerial and subaqueous delta progradation: Morphodynamic modeling of compound-clinoform
development,
J. Geophys. Res.,
110,
F02013,
doi:10.1029/2004JF000265.
Copyright 2005 by the American Geophysical Union.
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