Flow structure and channel morphology at a natural confluent meander bend

Riley, James D.; Rhoads, Bruce L.

doi:10.1016/j.geomorph.2011.06.011

Cited by 111 publications

(102 citation statements)

References 47 publications

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“…The tendency of larger tributaries to connect with the trunk stream on the outside of meander bends, and the general absence of confluences inside bends has been noted before (Callaway, 1902;Davis, 1903;Flint, 1980;Abrahams, 1984;Riley and Rhoads, 2012) has not been studied in the region, but has been noted elsewhere (Jennings et al, 1976;Frank and Jennings, 1979;Mylroie and Mylroie, 1990;Fabel et al, 1996;Worthington, 2005;Mocochain et al, 2009), and ground water flow studies in Kentucky have found evidence of meander by-passing by subsurface flow (Ray and Blair, 2005).…”

Section: Discussion and Interpretationsmentioning

confidence: 73%

Badass geomorphology

Phillips

2014

Earth Surf Processes Landf

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The archetypal badass is individualistic, non-conformist, and able to produce disproportionate results. The badass concept is applied here to geomorphology. The individualistic concept of landscape evolution (ICLE) is introduced, based on three propositions: excess evolution space, capacity of all landforms to change, and variable selection pressure from environmental factors within and encompassing landscapes. ICLE indicates that geomorphic systems are idiosyncratic to some extent, and that even where two systems are similar, this is a happenstance of similar environmental selection, not an attractor state. As geomorphic systems are all individualistic, those that are also non-conformist with respect to conventional wisdoms and have amplifier effects are considered badass. Development of meander bends on a section of the Kentucky River illustrates these ideas. The divergence of karst and fluvial forms on the inner and outer bends represents unstable amplifying effects. The divergence is also individualistic, as it can be explained only by combining general laws governing surface and subsurface flow partitioning with a specific geographical and environmental setting and the history of Quaternary downcutting of the Kentucky River. Landscape evolution there does not conform to any conventional theories or conceptual frameworks of geomorphology. The badass traits of many geomorphic systems have implications for the systems themselves, attitudes toward geomorphic practice, and appreciation of landforms. Badass geomorphology and the ICLE reflect a view, and approach to the study of, landforms as the outcome of the interplay of general laws, place-specific controls, and history. Badass geomorphology also implies a research style receptive to contraventional This article is protected by copyright. All rights reserved.wisdoms. Aesthetically, amplifier effects and individualism guarantee an essentially infinite variety of landforms and landscapes that geoscientists can appreciate both artistically and scientifically. Non-conformity makes the interpretation and understanding of this variety more challenging-and while that increases the degree of difficulty, it also makes for more interesting and compelling professional challenges.

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Section: Discussion and Interpretationsmentioning

confidence: 73%

Badass geomorphology

Phillips

2014

Earth Surf Processes Landf

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“…These features have led to increased use of ADCPs by researchers, and a wide range of studies exploiting the ADCP and dealing with flow structure and turbulence have been published [18,42,[48][49][50][51][52], some of them focusing on meandering rivers [25,42,49,52]. In most of these studies, however, the 3D flow distribution have been measured along cross-sections and thus the measurements have not covered the whole bend, facing partly similar problems related to the traditional methods [5,49,52]. Although transect-based ADCP measurements are much more efficient than traditional methods and allow for deep-river investigations, they add limited value to the understanding of riverine processes.…”

Section: Adcp-principles and Applicationsmentioning

confidence: 99%

Flow Patterns and Morphological Changes in a Sandy Meander Bend during a Flood—Spatially and Temporally Intensive ADCP Measurement Approach

Kasvi

Laamanen²,

Lotsari

et al. 2017

Water

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Abstract:The fluvio-geomorphological processes in meander bends are spatially uneven in distribution. Typically, higher velocities and erosion take place near the outer bank beyond the bend apex, while the inner bend point bar grows laterally towards the outer bank, increasing the bend amplitude. These dynamics maintain the meander evolution. Even though this development is found in meandering rivers independent of soil or environmental characteristics, each river still seems to behave unpredictably. The special mechanisms that determine the rate and occasion of morphological changes remain unclear. The aim of this study is to offer new insights regarding flow-induced morphological changes in meander using a novel study approach. We focused on short-term and small-spatial-scale changes by conducting a spatially and temporally (daily) intensive survey during a flood (a period of nine days) with an ADCP attached to a remotely controlled mini-boat. Based on our analysis, the flood duration and the rate of discharge increase and decrease seems to play key roles in determining channel changes by controlling the flow velocities and depth and the backwater effect may have notable influence on the morphological processes. We discuss themes such as the interaction of inner and outer bend processes and the longer-term development of meander bends.

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“…Several research works dealt with the need to model the distribution of the main flow, the magnitude of the secondary flow, the direction of the bed shear stress and the curvature induced additional energy losses in high curvature bends (e.g., Blanckaert and de Vriend [23]). Riley and Rhoads [33] investigated the flow structure where complex natural and artificial singularities impact the flow (i.e., at confluences and bifurcations). Eddy-resolving numerical models are used to investigate the flow processes, which include secondary flow, large scale coherent turbulence structures, shear layers and flow separation at the convex inner bank [34].…”

Section: Computational Fluid Dynamics Models In the Framework Of Curvmentioning

confidence: 99%

On the Simulation of Floods in a Narrow Bending Valley: The Malpasset Dam Break Case Study

Biscarini

Francesco

Ridolfi

et al. 2016

Water

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Abstract:In this paper, we investigate the performance of three-dimensional (3D) hydraulic modeling when dealing with river sinuosity and meander bends. In river bends, the flow is dominated by a secondary current, which has a key role on the flow redistribution. The secondary flow induces transverse components of the bed shear stress and increases the velocity in outward direction, thus generating local erosion and riverbed modifications. When in river bends, the 3D processes prevail, and a 3D computational fluid dynamics (CFD) model is required to correctly predict the flow structure. An accurate description of the different hydrodynamic processes in mildly and sharply curved bends find a relevant application in meanders migration modeling. The mechanisms that drive the velocity redistribution in meandering channels depend on the river's roughness, the flow depth (H), the radius curvature (R), the width (B) and the bathymetric variations. Here, the hydro-geomorphic characterization of sharp and mild meanders is performed by means of the ratios R/B, B/H, and R/H, and of the sinuosity index. As a case study, we selected the Malpasset dam break on the Reyran River Valley (FR), as it is perfectly suited for investigating performances and issues of a 3D model in simulating the inundation dynamics in a river channel with a varying curvature radius.

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Flow structure and channel morphology at a natural confluent meander bend

Cited by 111 publications

References 47 publications

Badass geomorphology

Badass geomorphology

Flow Patterns and Morphological Changes in a Sandy Meander Bend during a Flood—Spatially and Temporally Intensive ADCP Measurement Approach

On the Simulation of Floods in a Narrow Bending Valley: The Malpasset Dam Break Case Study

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