Title: Distributary Channel Networks as Moving Boundaries: Causes and Morphodynamic Effects

Abstract

In this study, we propose an exploratory model to describe the morphodynamics of distributary channel network growth on river deltas. The interface between deep channels and the shallow, unchannelized delta front deposits is modeled as a moving boundary. Steady flow over the unchannelized delta front is friction dominated and modeled by Laplace's equation. Shear stress along the network boundary produces nonlinear erosion rates at the interface, causing the boundary to move and network elements (channels and branches) to form. The model was run for boundary conditions resembling the Wax Lake Delta in coastal Louisiana, 20 parameterizations of sediment transport, and 3 parameterizations of discharge. In each case, the model produced a complex channel network with channel number, width, bifurcation angle, and channel shape depending on the sediment transport formula. For reasonable sediment transport parameters and gradually increasing water discharge, the model produced network characteristics and progradation rates similar to theWax Lake Delta. Lastly, this suggests that the model contains the processes responsible for network growth, despite its abstract formulation.

Authors:

Ke, Wun‐Tao  ^[1];

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Shaw, John B.  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-0581-0857"
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Mahon, Robert C.  ^[2];

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Cathcart, Christopher A.  ^[1]

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• Search DOE PAGES for ORCID "0000-0002-0023-2245"
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+ Show Author Affiliations

1. Univ. of Arkansas, Fayetteville, AR (United States)
2. Univ. of Arkansas, Fayetteville, AR (United States); Univ. of New Orleans, LA (United States)

Publication Date:

2019-06-08

Research Org.:

Univ. of Arkansas, Fayetteville, AR (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)

OSTI Identifier:

1598314

Alternate Identifier(s):

OSTI ID: 1543066

Grant/Contract Number:  

SC0016163; EAR‐1246761

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Geophysical Research. Earth Surface

Additional Journal Information:

Journal Volume: 124; Journal Issue: 7; Journal ID: ISSN 2169-9003

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; river delta; morphodynamics; moving boundary; Laplace's equation