Flow patterns and morphology of a prograding river delta

Journal of Geophysical Research F: Earth Surface - Tập 121 Số 2 - Trang 372-391 - 2016
John Shaw1,2,3, David Mohrig3, Wayne Wagner3
1Department of Geology and Geophysics University of Wyoming Laramie Wyoming USA
2Department of Geosciences, University of Arkansas, Fayetteville, Arkansas, USA
3Jackson School of Geosciences, University of Texas at Austin, Austin, Texas, USA

Tóm tắt

AbstractThe transition of flow between laterally confined channels and the unchannelized delta front controls the morphodynamic evolution of river deltas but has rarely been measured at the field scale. We quantify flow patterns and bathymetry that define the evolution of the subaqueous delta front on the Wax Lake Delta, a rapidly prograding delta in coastal Louisiana. A significant portion of flow (∼59%) departs the channel network over lateral channel margins as opposed to the downstream channel tips. Bathymetric surveys and remotely sensed estimates of flow direction allow spatial changes in flow velocity to be quantified and patterns of erosion and deposition to be estimated. Shallowing along channel margins produces spatial acceleration and erosion. Lateral spreading, deceleration, and deposition occur within three to eight channel widths outside of the channel margins. In interdistributary bays, the shape of each flow path is constrained by “nourishment boundaries” that separate the outflows from neighboring channels. Deposit elevation decreases with a basinward slope of 2.4 × 10−4 with distance from a channel margin along any flow path, regardless of the channel or location that flow departed the network. Bathymetric depressions called “interdistributary troughs” form along nourishment boundaries where flow paths are the longest and deposit elevation is correspondingly low. We conclude that the deposit morphology exerts a strong control on bathymetric evolution and that interaction between neighboring channels and even neighboring deltas can influence delta front morphology.

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Tài liệu tham khảo

10.1016/j.geomorph.2003.10.005

Alpers W., 2004, Synthetic Aperture Radar Marine User'S Manual, 263

Bates C. C., 1953, Rational theory of delta formation, AAPG Bull., 37, 2119

10.1177/030913339501900402

10.1002/2013JF002965

10.1002/2013JC009312

10.1002/2013JF002810

10.1029/2000JC000728

10.1029/2006JF000574

10.1029/2010JF001955

10.1130/G32358.1

10.1029/96GL03009

10.1002/2014RG000451

10.1029/2010JF001802

10.1016/0141‐1136(93)90100‐E

10.1029/2009GL042000

10.1002/2014JF003408

Hack J. T., 1957, Studies of Longitudinal Stream Profiles in Virginia and Maryland , Geol. Surv. Prof. Pap.

10.1002/2014WR016149

10.1130/0016‐7606(1971)82[1355:SMOSC]2.0.CO;2

10.1029/93JC03308

10.1029/2007GL031823

10.1029/95JC02962

10.1002/2015GL066455

10.1029/2006JF000470

10.1002/esp.3268

Kundu P. K., 2011, Fluid Mechanics

10.1002/jgrc.20302

10.1002/2014JF003298

10.1002/jgrf.20134

Morisawa M., 1985, Models in Geomorphology, 239

10.1029/2012GL051788

NOAA(2012) Tides and Currents Lawma Amerada Pass LA. [Available athttp://tidesandcurrents.noaa.gov/data_menu.shtml?stn=8764227%20Lawma%20Amerada%20Pass%20LA&Historic+Tide+Data.]

10.1029/2011JF002026

10.1016/S0302‐3524(82)80015‐7

10.1146/annurev‐marine‐120709‐142856

10.1029/2007JF000977

10.1029/1999WR900237

Roberts H., 2003, An embryonic major delta lobe: A new generation of delta studies in the Atchafalaya‐Wax Lake delta system, Gulf Coast Assoc. Geol. Soc. Trans., 53, 690

10.1017/S0022112009006107

10.1029/2010WR009972

10.1073/pnas.0705265104

10.1130/G34751.1

10.1002/jgrf.20123

Smart J. S., 1971, Quantitative Properties of Delta Channel Networks

10.1139/s04‐032

10.1017/S0956792500004198

10.1002/2014WR016577

U.S. Geological Survey (USGS)(2012) National Water Information System data available on the World Wide Web (Water Data for the Nation). [Available athttp://waterdata.usgs.gov/nwis/] Accessed 2 Nov. 2012.

Wellner R., 2005, Jet‐plume depositional bodies—The primary building blocks of Wax Lake Delta, Gulf Coast Assoc. Geol. Soc. Trans., 55, 867

10.1126/science.1248765

10.1029/2007JF000855

10.1130/0016-7606(1977)88<857:STADAR>2.0.CO;2

10.1029/JC076i036p08649

10.1086/628028

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Journal of Geophysical Research F: Earth Surface

Tập 121 Số 2

372-391

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