Jorge D. Abad

Pontifícia Universidade Católica do Paraná

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Marcelo H. García

University of Illinois Urbana-Champaign

Eddy J. Langendoen

National Sedimentation Laboratory

Alejandro Mendoza

Universidad Nacional Autónoma de México

C. E. Frias

Gates (United States)

Bruce L. Rhoads

University of Illinois Urbana-Champaign

Kory Konsoer

Louisiana State University

Jim Best

University of Illinois Urbana-Champaign

Kamal El Kadi Abderrezzak

Laboratoire d'Hydraulique Saint-Venant

Ronald R. Gutiérrez

Pontifical Catholic University of Peru

Collin Ortals

University of Florida

Cooperative Institutions

University of Illinois Urbana-Champaign

Cornell University

Universidad de Ingeniería y Tecnología

University of Pittsburgh

Urbana University

University of Minnesota

Centre National de la Recherche Scientifique

Universidad Nacional Agraria La Molina

Pennsylvania State University

Laboratoire d'Hydraulique Saint-Venant

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High-resolution modeling of meander neck cutoffs: laboratory and field scales

Frontiers in Earth Science (2023)

Zhi Li Alejandro Mendoza Jorge D. Abad Theodore A. Endreny Bangshuai Han

Meandering rivers are distinguished by their characteristic sinuosity, which is subject to modulation through channel cutoff, resulting in the formation of oxbow lakes within the abandoned meander loops. Throughout the evolutionary course of a river, these cutoffs establish a connection between the channel and floodplain systems, both crucial to maintaining the dynamic equilibrium of the river system. Nonetheless, the interactive dynamic between the channel and floodplain and its influence on the transient behavior of the channel’s morphodynamics during a cutoff event are frequently reduced to simplistic representations in computational models. This study introduces a comprehensive numerical model that elucidates the adaptive processes of bed and planform during and subsequent to the inception of cutoff and oxbow lakes. The model is assessed through its application to a laboratory scale cutoff, before being employed to a real-world meandering river, specifically the Ucayali River in Peru, in order to gain understanding into channel development and the intricate patterns of planform dynamics following cutoff events. The model is able to capture the main modes of planform migration, translation and expansion for the case of the bend in the Ucayali River. During the neck cutoff, the model simulates the progression of erosional and depositional waves traveling in upstream and downstream directions respectively, underscoring the importance of incorporating both hydrodynamic and morphodynamic factors in characterizing the river dynamics associated with meander cutoffs.

Meander (mathematics)

Beach morphodynamics

Sinuosity

Cut-off

Bank erosion

Stream power

10.3389/feart.2023.1208782

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Citations (8)

Advances and challenges in meandering channels research

Geomorphology (2012)

İnci Güneralp Jorge D. Abad Guido Zolezzi Janet Hooke

Reductionism

10.1016/j.geomorph.2012.04.011

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Citations (92)

On the governing equations for horizontal and vertical coupling of one- and two-dimensional open channel flow models

Journal of Hydraulic Research (2019)

Cesar Simon Eddy J. Langendoen Jorge D. Abad Alejandro Mendoza

One-dimensional (1D) models of open-channel flow are efficient for simulating in-channel hydrodynamics over long reaches and time periods, but cannot accurately simulate overbank flows that require two-dimensional (2D) models. The derivation and discussion of the behaviour of the coupling terms for horizontal and vertical coupling of the governing equations of 1D and 2D flow are presented here for the first time. Transfer terms for mass and momentum are introduced. Also, for the first time, the quantification of these transfer terms for the case of an experimental meandering channel with overbank flow is presented. For both coupling methods and relatively high overbank flow depth, the advective momentum transfer exceeded the diffusive momentum transfer. The diffusive momentum transfer has similar magnitude between both coupling approaches. The advective momentum transfer was one order of magnitude higher for the horizontal-coupling approach than for the vertical-coupling approach.

Overbank

Momentum (technical analysis)

Momentum transfer

Momentum diffusion

10.1080/00221686.2019.1671507

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Citations (1)

Effect of Sediment Transport Boundary Conditions on the Numerical Modeling of Bed Morphodynamics

Journal of Hydraulic Engineering (2016)

Alejandro Mendoza Jorge D. Abad Eddy J. Langendoen Dongchen Wang Pablo Tassi

Experimental sediment transport and river morphologic studies in laboratory flumes can use two sediment-supply methods: an imposed feed at the upstream end, or a recirculation of sediment from the downstream end to the upstream end. These methods generally produce similar equilibrium bed morphology, but temporal evolution can differ. The adjustment of natural rivers may be reproduced by both modes. Nevertheless, computer models of river morphodynamics typically use a sediment-feed boundary condition, which can impact the simulated evolution of transient features such as bedforms. The effect of sediment transport boundary conditions on bedform dynamics was analyzed through numerical experiments using a two-dimensional, depth-averaged sediment transport model. Two different boundary conditions were imposed at the inlet (constant sediment feed and sediment recirculated from the outlet) for two bedform scales (dunes and bars). The type of sediment transport boundary condition greatly influenced dune development. The sediment-recirculating condition produced a more dynamic bed morphology with dunes of higher amplitude. The associated zones of higher shear stress had a direct impact on the hydrodynamics and patterns of sediment transport. In the case of the bar bed morphology, the simulated bars had similar mean length and height for both sediment boundary conditions. However, the sediment-recirculating case produced a more dynamic bed, in which the dominant bar length varied over time. Finally, the simulated bed morphology with bars, agreed much better with that observed when using a calibrated sediment transport equation to match sediment discharges instead of the standard empirical sediment transport equations available in literature.

Beach morphodynamics

Bedform

Sedimentary budget

10.1061/(asce)hy.1943-7900.0001208

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Citations (27)

Correction [to “Workshop discusses database for Marcellus water issues”]

Eos (2012)

Susan L. Brantley Candie C. Wilderman Jorge D. Abad

10.1029/2012eo360005

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Errors in Acoustic Doppler Profiler Velocity Measurements Caused by Flow Disturbance

Journal of Hydraulic Engineering (2007)

David S. Mueller Jorge D. Abad Carlos M. García Jeffery W. Gartner Marcelo H. García

Acoustic Doppler current profilers (ADCPs) are commonly used to measure streamflow and water velocities in rivers and streams. This paper presents laboratory, field, and numerical model evidence of errors in ADCP measurements caused by flow disturbance. A state-of-the-art three-dimensional computational fluid dynamic model is validated with and used to complement field and laboratory observations of flow disturbance and its effect on measured velocities. Results show that near the instrument, flow velocities measured by the ADCP are neither the undisturbed stream velocity nor the velocity of the flow field around the ADCP. The velocities measured by the ADCP are biased low due to the downward flow near the upstream face of the ADCP and upward recovering flow in the path of downstream transducer, which violate the flow homogeneity assumption used to transform beam velocities into Cartesian velocity components. The magnitude of the bias is dependent on the deployment configuration, the diameter of the instrument, and the approach velocity, and was observed to range from more than 25% at 5cm from the transducers to less than 1% at about 50cm from the transducers for the scenarios simulated.

Acoustic Doppler velocimetry

Mean flow

10.1061/(asce)0733-9429(2007)133:12(1411)

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Citations (67)

2D and 3D numerical simulations of morphodynamics structures in large-amplitude meanders

CRC Press eBooks (2014)

D Wang Pablo Tassi Kamal El Kadi Abderrezzak Alejandro Mendoza Jorge D. Abad

The appearance of the regular vegetated ridge patterns observed in some ephemeral rivers of semi-arid regions (Nanson, Tooth, & Knigthon 2002) has previously been explained by hydraulic arguments (optimization of the bed load transport capacity, see Huang & Nanson (2007)) without including the role of vegetation in the process. Those arguments provide neither the conditions under which the more efficient anabranching system can be realized nor a description of the dynamics leading to anabranching. As an alternative, we propose a simplified model accounting for the flow-mediated interactions between riparian vegetation located at different points of the river channel. Classically, the appearance of river morphologic features is explained by the equations of morphodynamics. However, due to the complexity of the action of vegetation on the flow and on sediment transport, a complete physically-based set of coupled ecomorphodynamic equations is not available yet. We propose an effective model for the interactions between vegetated obstacles. Depending on the relative position of the obstacles, one observes either positive or negative feedbacks: on the lee-side of a permeable obstacle, flood sheltering may occur and favor deposition that helps in turn the establishment of biomass, conversely scouring is increased laterally due to obstacle-induced flow diversion (Zong & Nepf 2010). In the situation where the hydrological timescale (flooding frequency for a given effective magnitude) and the biological timescale (vegetation development rate) are comparable, the spatially inhomogeneous feedbacks can result in the appearance of organized regular structures. Aerial photographs give us the characteristic morphological scale of patterns. We then perform a stability analysis of our model and derive a set of conditions under which the combination of hydrological, ecological and pedological factors allows the formation of anabranching patterns. We discuss the role of the different ingredients in relation to the fluvial environments in which such patterns typically emerge. Finally, we conjecture on the relevance of the proposed mechanism to explain ubiquitous vegetated scroll bars that are observed on the interior of meander bends.

Beach morphodynamics

10.1201/b17133-149

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Citations (11)

Modification of meander migration by bank failures

Journal of Geophysical Research Earth Surface (2014)

Davide Motta Eddy J. Langendoen Jorge D. Abad Marcelo H. García

Meander migration and planform evolution depend on the resistance to erosion of the floodplain materials. To date, research to quantify meandering river adjustment has largely focused on resistance to erosion properties that vary horizontally. This paper evaluates the combined effect of horizontal and vertical floodplain material heterogeneity on meander migration by simulating fluvial erosion and cantilever and planar bank mass failure processes responsible for bank retreat. The impact of stream bank failures on meander migration is conceptualized in our RVR Meander model through a bank armoring factor associated with the dynamics of slump blocks produced by cantilever and planar failures. Simulation periods smaller than the time to cutoff are considered, such that all planform complexity is caused by bank erosion processes and floodplain heterogeneity and not by cutoff dynamics. Cantilever failure continuously affects meander migration, because it is primarily controlled by the fluvial erosion at the bank toe. Hence, it impacts migration rates and meander shapes through the horizontal and vertical distribution of erodibility of floodplain materials. Planar failures are more episodic. However, in floodplain areas characterized by less cohesive materials, they can affect meander evolution in a sustained way and produce preferential migration patterns. Model results show that besides the hydrodynamics, bed morphology and horizontal floodplain heterogeneity, floodplain stratigraphy can significantly affect meander evolution, both in terms of migration rates and planform shapes. Specifically, downstream meander migration can either increase or decrease with respect to the case of a homogeneous floodplain; lateral migration generally decreases as result of bank protection due to slump blocks; and the effect on bend skewness depends on the location and volumes of failed bank material caused by cantilever and planar failures along the bends, with possible achievement of downstream bend skewness under certain conditions.

Meander (mathematics)

Bank erosion

Bank

10.1002/2013jf002952

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Citations (75)

Three‐dimensional flow structure and bed morphology in large elongate meander loops with different outer bank roughness characteristics

Water Resources Research (2016)

Kory Konsoer Bruce L. Rhoads Jim Best Eddy J. Langendoen Jorge D. Abad

Abstract Few studies have examined the three‐dimensional flow structure and bed morphology within elongate loops of large meandering channels. The present study focuses on the spatial patterns of three‐dimensional flow structure and bed morphology within two elongate meander loops and examines how differences in outer bank roughness influence near‐bank flow characteristics. Three‐dimensional velocities were measured during two different events—a near‐bankfull flow and an overbank event. Detailed data on channel bathymetry and bed form geometry were obtained during a near‐bankfull event. Flow structure within the loops is characterized by strong topographic steering by the point bar, by the development of helical motion associated with flow curvature, and by acceleration of flow where bedrock is exposed along the outer bank. Near‐bank velocities during the overbank event are less than those for the near‐bankfull flow, highlighting the strong influence of the point bar on redistribution of mass and momentum of the flow at subbankfull stages. Multiple outer bank pools are evident within the elongate meander loop with low outer bank roughness, but are not present in the loop with high outer bank roughness, which may reflect the influence of abundant large woody debris on near‐bank velocity characteristics. The positions of pools within both loops can be linked to spatial variations in planform curvature. The findings indicate that flow structure and bed morphology in these large elongate loops is similar to that in small elongate loops, but differs somewhat from flow structure and bed morphology reported for experimental elongate loops.

Meander (mathematics)

Overbank

Point bar

Bank erosion

10.1002/2016wr019040

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Citations (73)

A simplified 2D model for meander migration with physically-based bank evolution

Geomorphology (2011)

Davide Motta Jorge D. Abad Eddy J. Langendoen Marcelo H. García

Meander (mathematics)

Bank erosion

Planform

10.1016/j.geomorph.2011.06.036

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Citations (145)