Morphological modelling of rivers with erodible banks

Mosselman, E.

doi:10.1002/(sici)1099-1085(19980630)12:8<1357::aid-hyp619>3.3.co;2-z

Cited by 36 publications

(40 citation statements)

References 9 publications

(14 reference statements)

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“…Their conclusion was that the comparison of modelling results to geomorphological data and to flume experiments was unsatisfactory and a computer model cannot yet be applied to the timescales of interest for geological problems. Mosselman (1998) used a morphological model (based on bank erosion and associated planform change) to simulate the meandering Ohre River in the Czech Republic. Unfortunately, no good agreement between modelling results and field observations was found, but this was ascribed to shortcomings in the flow and bed topography sub-models.…”

Section: Meander Models and Their Applicationsmentioning

confidence: 99%

Simulating meander evolution of the Geul River (the Netherlands) using a topographic steering model

Moor

Balen

Kasse

2007

Earth Surf Processes Landf

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Active meandering rivers are capable of reworking and removing large quantities of valuable land. Therefore, understanding the characteristics of meandering rivers and predicting future meander behaviour can be of great value for local authorities. In this study, we apply a topographic steering meander model to the Geul River (southern Netherlands), using field data to calibrate the model. The present channel characteristics of the Geul River were mapped in the field. Cut-banks were classified as erosive, unstable or stable. The model outcomes were compared with these field data.Several model runs were carried out, using different sets of parameter values. After studying the results and using the field data, we introduced the concept of a variable channel width in the simulation model. In reality, the river has different channel widths varying from 8 to more than 15 m. These widths are a linear function of local curvature. The model runs using a variable channel width show that the model is capable of predicting locations of lateral migration in conformity with observed active lateral migration and erosive banks. With both models, the sediment reworking time of the floodplain can be calculated. Floodplain reworking times of 200-300 years were calculated. In combination with the lateral migration rate, this reworking time is an important element in catchment sediment budget calculations. (Van de Riet et al., 2005). The meandering river is (partly) responsible for the decrease of the zinc violet due to lateral erosion and dilution of the contaminated sediments. A meander model can provide insight into the volumes of (contaminated) sediment being reworked. In addition, understanding the meander dynamics can also provide valuable information on the protection of vulnerable floodplain flora.In this paper, we examine the meandering character of the Geul River using a numerical river meandering model. Our main aim is to test and calibrate a topographic steering meander model, developed by Lancaster (1998) and Lancaster and Bras (2002). The key question is whether the model is able to simulate the meandering pattern of the Geul River and may be used to predict future meander patterns in the catchment. In this case study, special attention is paid to the incorporation of a variable channel width in the model. Furthermore, we discuss some geomorphological implications of the results and model capabilities, with the mining contaminated sediments as an important example.of the Geul river, with a very diverse character, including rapid lateral migrating bends, straightened sections, stable sections and sections with bank protection. The present-day migration character of this stretch has been determined in the field, and at two locations estimates of the lateral migration rates are present (Spanjaard, 2004). The coordinates of the current position of the Geul River were derived from a detailed digital elevation model (horizontal resolution 5 m). The coordinates were imported into the input file for the computer model. This st...

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Section: Meander Models and Their Applicationsmentioning

confidence: 99%

Simulating meander evolution of the Geul River (the Netherlands) using a topographic steering model

Moor

Balen

Kasse

2007

Earth Surf Processes Landf

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“…However, when studying the long‐term evolution of meandering rivers the above picture simplifies, because the separate effects of riverbank erosion and accretion are no longer distinguishable over the very long timescale of planform development (Ikeda et al, ; Mosselman, ; Lanzoni & Seminara, ). This hypothesis, which is supported by empirical observations (Pizzuto & Meckelnburg, ; Luchi et al, ), allows one to treat bank erosion and bank accretion as continuous averaged processes driven by appropriate representative hydraulic conditions (Seminara et al, ; Lanzoni & Seminara, ; Zolezzi et al, ; Eke et al, ).…”

Section: Introductionmentioning

confidence: 99%

The Hydraulic Geometry of Evolving Meandering Rivers

Monegaglia

Tubino

2019

JGR Earth Surface

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We study the bankfull hydraulic geometry of evolving meander bends. The analysis is driven by the recognition that none of the models introduced so far accounts for the conservation of the sediment mass, which leads to an unrealistic drop of the sediment transport capacity while the meander becomes longer. With this aim we propose a novel model to predict the adaptation of channel width and slope in evolving meanders, which is composed of a threshold relationship for the channel width and an ordinary differential equation for the slope, arising from an integral, meander‐averaged formulation of the Exner equation. The latter accounts for three main processes: (i) meander elongation, (ii) width change, and (iii) bed aggradation due to reduction of the transport capacity. Our model predicts a reduction of both channel width and slope, whose magnitude is regulated by the parameter RT representing the ratio between the timescale of river planform and that of riverbed. When this ratio is large, the bankfull hydraulic geometry keeps nearly invariable; on the contrary, when RT is small, as channel sinuosity increases, the bankfull width and slope experience a significant change. Through remote sensing analysis and published data we provide estimates of the parameter RT for several meandering river reaches. We also trace the changes of the bankfull width of four dynamic meandering rivers in the Amazon basin by means of an innovative multitemporal bend‐scale analysis. Observed evolutionary trajectories are satisfactorily reproduced by theoretical predictions.

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“…To this end, there have been extensive research efforts which have almost exclusively focused on modeling the relevant biogeotechnical properties of bank erosion [e.g.. Darby and Thorne , ; Darby et al ., ; Langendoen and Simon , ]. These findings have on occasion been directly applied to meander migration models [e.g., Mosselman , ; Darby et al ., ; Rinaldi et al ., ; Duan and Julien , ; Motta et al ., ]. (2) The explicit assumption of a constant river channel width makes it impossible to predict channel widening, chute cutoffs, and the general width variation patterns observed in nature [ Parker et al ., ; Brice , ; Lagasse et al ., ; Peyret , ; Zolezzi et al ., ].…”

Section: Introductionmentioning

confidence: 99%

Numerical modeling of erosional and depositional bank processes in migrating river bends with self‐formed width: Morphodynamics of bar push and bank pull

2014

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Meandering rivers display active communication between bank erosion and bar deposition processes. How does this occur? How does the river select its width? To answer these questions, we implement a model for meander migration where both bank processes (erosion and deposition) are considered independently. Bank erosion is modeled as erosion of purely noncohesive bank material damped by natural slump block armoring; channel deposition is modeled via flow-retarded vegetal encroachment. Both processes are tied to a slope-dependent channel forming Shields number; banks with near-bank Shields number below this value undergo deposition, and those above it undergo erosion. Channel-forming Shields number must increase with slope, as dictated by available data and model performance. Straight channel modeling shows that a channel arrives at an equilibrium width from any initial condition. For the channel bend, the river always approaches an asymptotic state where width reduces slowly in time and where bank erosion and deposition occur at nearly equal rates. Before this state is reached, however, the river follows a phase-plane trajectory with four possible regimes: (a) both banks erode, (b) both banks deposit, (c) both banks migrate outward, but with a faster depositing bank (bar push), and (d) both banks migrate outward, but with a faster eroding bank (bank pull). The trajectory of migration on the phase plane depends on initial conditions and input parameters controlling the rate of depositional and erosional migration. All input parameters have specific physical meaning, and the potential to be measured in the field.

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Morphological modelling of rivers with erodible banks

Cited by 36 publications

References 9 publications

Simulating meander evolution of the Geul River (the Netherlands) using a topographic steering model

Simulating meander evolution of the Geul River (the Netherlands) using a topographic steering model

The Hydraulic Geometry of Evolving Meandering Rivers

Numerical modeling of erosional and depositional bank processes in migrating river bends with self‐formed width: Morphodynamics of bar push and bank pull

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