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Distributary Channel Networks as Moving Boundaries: Causes and Morphodynamic Effects
Author(s) -
Ke WunTao,
Shaw John B.,
Mahon Robert C.,
Cathcart Christopher A.
Publication year - 2019
Publication title -
journal of geophysical research: earth surface
Language(s) - English
Resource type - Journals
eISSN - 2169-9011
pISSN - 2169-9003
DOI - 10.1029/2019jf005084
Subject(s) - beach morphodynamics , geology , sediment transport , channel (broadcasting) , delta , sediment , progradation , geomorphology , river delta , erosion , hydrology (agriculture) , mechanics , geotechnical engineering , physics , engineering , telecommunications , astronomy , facies , structural basin
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 the Wax Lake Delta. This suggests that the model contains the processes responsible for network growth, despite its abstract formulation.