Numerical simulation of bank erosion and channel migration in meandering rivers

2002 ◽  
Vol 38 (9) ◽  
pp. 2-1-2-21 ◽  
Author(s):  
Stephen E. Darby ◽  
Andrei M. Alabyan ◽  
Marco J. Van de Wiel
2014 ◽  
Vol 760 ◽  
pp. 127-174 ◽  
Author(s):  
Esther C. Eke ◽  
M. J. Czapiga ◽  
E. Viparelli ◽  
Y. Shimizu ◽  
J. Imran ◽  
...  

AbstractThis research implements a recently proposed framework for meander migration, in order to explore the coevolution of planform and channel width in a freely meandering river. In the model described here, width evolution is coupled to channel migration through two submodels, one describing bank erosion and the other describing bank deposition. Bank erosion is modelled as erosion of purely non-cohesive bank material damped by natural armouring due to basal slump blocks, and bank deposition is modelled in terms of a flow-dependent rate of vegetal encroachment. While these two submodels are specified independently, the two banks interact through the medium of the intervening channel; the morphodynamics of which is described by a fully nonlinear depth-averaged morphodynamics model. Since both banks are allowed to migrate independently, channel width is free to vary locally as a result of differential bank migration. Through a series of numerical runs, we demonstrate coevolution of local curvature, width and streamwise slope as the channel migrates over time. The correlation between the local curvature, width and bed elevation is characterized, and the nature of this relationship is explored by varying the governing parameters. The results show that, by varying a parameter representing the ratio between a reference bank erosion rate and a reference bank deposition rate, the model is able to reproduce the broad range of river width–curvature correlations observed in nature. This research represents a step towards providing general metrics for predicting width variation patterns in river systems.


2018 ◽  
Vol 40 ◽  
pp. 02013
Author(s):  
Toshiki Iwasaki ◽  
Satomi Yamaguchi ◽  
Hiroki Yabe

An understanding of bedload transport processes is an essential research goal for better prediction of river morphology and morphodynamics as well as the transport and fate of sediment-bound materials in river systems. Passive tracer particles have been used widely to monitor bedload transport processes in rivers by measuring the spatiotemporal distribution of the bedload tracers. Here, we propose a numerical model for reproducing the transport of bedload tracers in river systems, more specifically, the behaviours of bedload tracers under the influence of complex river morphodynamics. A two-dimensional morphodynamic model is combined with a flux-based bedload tracer model with use of the active layer approach. The model is applied to a laboratory experiment that demonstrates the transport processes within the channel of bedload tracers supplied from the floodplain. The numerical model effectively reproduces the main features of the experiment, namely, the bedload tracers supplied from the floodplain due to bank erosion deposit onto sand bars developed within the channel. Because the sand bars cause a very long residence time of the bedload tracers within the bed, the transport speed of the tracers is slowed significantly under the influence of bar formation and channel migration.


Author(s):  
D. Neupane ◽  
P. Gyawali ◽  
D. Tamang

<p><strong>Abstract.</strong> Channel migration becomes the main characteristic of major rivers of Mohana-Macheli watershed of western Nepal. Study of river channel migration of major rivers of watershed using freely available remote sensing show that the channel has shifted to as high as 1000 meters from the original river path over the span of 9 years (2009–2017). The channel migration directly affects the land use and it has direct effect on the flood plain settlements of the study area. Cultivation of sugarcane in sand area is one of the mitigating measures of flood effects and prevent river bank erosion. The study shows that the area of sand is changing disproportionately in the region. This paper presents an enhanced change detection method of river channel migration using remotely sensed images and identification of sand area using classification and interpretation technique.</p>


2008 ◽  
Vol 44 (9) ◽  
Author(s):  
Massimo Rinaldi ◽  
Beatrice Mengoni ◽  
Laura Luppi ◽  
Stephen E. Darby ◽  
Erik Mosselman

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