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A combined nonlinear and nonlocal model for topographic evolution in channelized depositional systems

Falcini, F. and Foufoula-Georgiou, E. and Ganti, V. and Paola, C. and Voller, V. R. (2013) A combined nonlinear and nonlocal model for topographic evolution in channelized depositional systems. Journal of Geophysical Research. Earth Surface, 118 (3). pp. 1617-1627. ISSN 2169-9003.

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Models for the overall topographic evolution of erosional and depositional systems can be grouped into two broad classes. The first class is local models in which the sediment flux at a point is expressed as a linear or nonlinear function of local hydrogeomorphic measures (e.g., water discharge and slope). The second class is nonlocal models, where the sediment flux at a point is expressed via a weighted average (i.e., convolution integral) of measures upstream and/or downstream of the point of interest. Until now, the nonlinear and nonlocal models have been developed independently. In this study, we develop a unified model for large-scale morphological evolution that combines both nonlinear and nonlocal approaches. With this model, we show that in a depositional system, under piston-style subsidence, the topographic signatures of nonlinearity and nonlocality are identical and that in combination, their influence is additive. Furthermore, unlike either nonlinear or nonlocal models alone, the combined model fits observed fluvial profiles with parameter values that are consistent with theory and independent observations. By contrast, under conditions of steady bypass, the nonlocal and nonlinear components in the combined model have distinctly different signatures. In the absence of nonlocality, a purely nonlinear model always predicts a bypass fluvial profile with a spatially constant slope, while a nonlocal model produces a nonconstant slope, i.e., profile curvature. This result can be used as a test for inferring the presence of nonlocality and for untangling the relative roles of local and nonlocal mechanisms in shaping depositional morphology.

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Additional Information:© 2013 American Geophysical Union. Received 6 July 2012; revised 8 July 2013; accepted 9 July 2013; published 30 August 2013. This work was supported by the STC program of the National Science Foundation via the National Center for Earth-Surface Dynamics under the agreement number EAR-0120914 and by the Flagship Project RITMARE to FF, funded by the Italian Ministry of Education, University and Research within the National Research Program 2011–2013. The authors are grateful for fruitful discussion and input from Roberto Garra and Alessandra Lanotte. The authors are also indebted to the editor Alexander Densmore, associate editor Dimitri Lague, and reviewers Nate Bradley, Philippe Davy, and David Furbish of the manuscript for providing informative and intellectually rich comments.
Funding AgencyGrant Number
NSF STC ProgramEAR-0120914
Italian Ministry of EducationUNSPECIFIED
Subject Keywords:sediment transport; nonlocality; non-linearity; depositional system
Issue or Number:3
Record Number:CaltechAUTHORS:20131203-082654234
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Official Citation:Falcini, F., E. Foufoula-Georgiou, V. Ganti, C. Paola, and V. R. Voller (2013), A combined nonlinear and nonlocal model for topographic evolution in channelized depositional systems, J. Geophys. Res. Earth Surf., 118, 1617–1627, doi:10.1002/jgrf.20108
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:42786
Deposited By: Tony Diaz
Deposited On:03 Dec 2013 16:51
Last Modified:03 Oct 2019 06:01

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