Channel instability as a control on silting dynamics and vegetation patterns within perifluvial aquatic zones

Piégay, Hervé; Bornette, Gudrun; Citterio, A.; Herouin, Eric; Moulin, Bertrand; Statiotis, C.

doi:10.1002/1099-1085(200011/12)14:16/17<3011::aid-hyp132>3.0.co;2-b

Cited by 92 publications

(59 citation statements)

References 29 publications

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“…The process of chute cutoff behaviour significantly affects the dynamics of a stream, which is essential to create physical habitats. Continuous opening and closure of scroll-slough cutoffs result in increasing environmental severity; whereas the bend cutoff leads to abandonment and formation of oxbow lakes, which are the 'hot spot' providing habitat for numerous plant and wildlife species (Ward et al, 1999;Piégay et al, 2000).…”

Section: Implications and Applicationsmentioning

confidence: 99%

Bifurcation instability and chute cutoff development in meandering gravel-bed rivers

et al. 2014

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. (2014) 'Bifurcation instability and chute cuto development in meandering gravel-bed rivers. ', Geomorphology., Further information on publisher's website:http://dx.doi.org/10.1016/j.geomorph.2014.01.018Publisher's copyright statement: NOTICE: this is the author's version of a work that was accepted for publication in Geomorphology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reected in this document. Changes may have been made to this work since it was submitted for publication. A denitive version was subsequently published in Geomorphology, 213, 15 May 2014, 10.1016/j.geomorph.2014.01.018. Additional information:Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractChute cutoffs reduce sinuosity of meandering rivers and potentially cause a transition from a single to a multiple channel river. The channel bifurcation of the main channel and the mouth of the incipient chute channel controls sediment and flow partitioning and development of the chute. Recent channel bifurcation models suggest that upstream bend radius, gradient advantage, inlet step, and upstream sediment supply at the bifurcation are important factors in the evolution of bifurcations. Our objective is to unravel the relative importance of these factors for chute cutoff success and development. We compare results from a morphodynamic three-dimensional (3D) model and a one-dimensional (1D) model with nodal-point relation with field observations of chute cutoffs in a meandering gravel-bed river. The balance between increased gradient advantage and flow curvature upstream of the chute channel bifurcation was systematically investigated with the 1D model. The 3D model runs and the field observations show the development of two types of chute cutoffs: a scroll-slough cutoff and a bend cutoff. The morphodynamic 3D model demonstrates that chutes are initiated when flow depth exceeds the floodplain elevation. Overbank flow and a significant gradient advantage result in a bend cutoff. The outcome of the 1D model shows that channel curvature at the bifurcation determines the success or failure of the chute cutoff when the chute channel is located at the inner bend, as in the case of scrollslough cutoffs. We conclude that chute initiation depends on floodplain characteristics, i.e., floodplain elevation, sediment composition, and the presence of vegetation. Chute cutoff success or failure is determined by the dynamics just upstream of the channel bi...

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Section: Implications and Applicationsmentioning

confidence: 99%

Bifurcation instability and chute cutoff development in meandering gravel-bed rivers

et al. 2014

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“…Threshold behaviour is also discussed in the context of the long-term development of soil structures and landforms (Newson and Newson, 2000;Phillips, 2004Phillips, , 2006, fluvial morphology (Willgoose et al, 1991a(Willgoose et al, , 1991bGrant, 1997;Piégay et al, 2000;Fryirs et al, 2007;Harnischmacher, 2007), rill and gully erosion (Bull and Kirkby, 1997;Kirkby et al, 2003;Poesen et al, 2003;Shao et al, 2005;Parkner et al, 2006Parkner et al, , 2007, badlands formation (CalvoCases and Harvey, 1996;Howard, 1997;Faulkner et al, 2000Faulkner et al, , 2003Boardman et al, 2003;Faulkner, 2008), and formation and growth of channel networks (Willgoose et al, 1991a(Willgoose et al, , 1991bRinaldo et al, 1996;Rodriguez-Iturbe et al, 1998;Rodriguez-Iturbe and Rinaldo, 2001). Threshold behaviour and feedbacks between vegetation patterns and redistribution of abiotic resources determine the resilience of geoecosystems in semi-arid regions (Grant, 1997;Piégay et al, 2000;Wilcox et al, 2003a;Wilcox and Newman, 2005;Fryirs et al, 2007;Saco et al, 2007;Tietjen and Jeltsch, 2007), grassland establishment (Baer et al, 2005;Baer and Blair, 2008), regeneration of forests in floodplain areas (Dufour and Piegay, 2008), plant diversity in wetlands …”

Section: Examples Of Threshold Behaviour In Hydrology and Earth Systementioning

confidence: 99%

Threshold behaviour in hydrological systems as (human) geo-ecosystems: manifestations, controls, implications

Zehe¹,

Sivapalan

2009

Hydrol. Earth Syst. Sci.

196

139

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Abstract. In this paper we review threshold behaviour in environmental systems, which are often associated with the onset of floods, contamination and erosion events, and other degenerative processes. Key objectives of this review are to a) suggest indicators for detecting threshold behavior, b) discuss their implications for predictability, c) distinguish different forms of threshold behavior and their underlying controls, and d) hypothesise on possible reasons for why threshold behaviour might occur. Threshold behaviour involves a fast qualitative change of either a single process or the response of a system. For elementary phenomena this switch occurs when boundary conditions (e.g., energy inputs) or system states as expressed by dimensionless quantities (e.g. the Reynolds number) exceed threshold values. Mixing, water movement or depletion of thermodynamic gradients becomes much more efficient as a result. Intermittency is a very good indicator for detecting event scale threshold behavior in hydrological systems. Predictability of intermittent processes/system responses is inherently low for combinations of systems states and/or boundary conditions that push the system close to a threshold. Post hoc identification of "cause-effect relations" to explain when the system became critical is inherently difficult because of our limited ability to perform observations under controlled identical experimental conditions. In this review, we distinguish three forms of threshold behavior. The first one is threshold behavior at the Correspondence to: E. Zehe (e.zehe@bv.tum.de) process level that is controlled by the interplay of local soil characteristics and states, vegetation and the rainfall forcing. Overland flow formation, particle detachment and preferential flow are examples of this. The second form of threshold behaviour is the response of systems of intermediate complexity -e.g., catchment runoff response and sediment yield -governed by the redistribution of water and sediments in space and time. These are controlled by the topological architecture of the catchments that interacts with system states and the boundary conditions. Crossing the response thresholds means to establish connectedness of surface or subsurface flow paths to the catchment outlet. Subsurface stormflow in humid areas, overland flow and erosion in semi-arid and arid areas are examples, and explain that crossing local process thresholds is necessary but not sufficient to trigger a system response threshold. The third form of threshold behaviour involves changes in the "architecture" of human geoecosystems, which experience various disturbances. As a result substantial change in hydrological functioning of a system is induced, when the disturbances exceed the resilience of the geo-ecosystem. We present examples from savannah ecosystems, humid agricultural systems, mining activities affecting rainfall runoff in forested areas, badlands formation in Spain, and the restoration of the Upper Rhine river basin as examples of this phenomenon. This fun...

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“…While some of these studies stress the dominant effect of hydrogeomorphological processes on plant communities (e.g. Piégay et al 2000;Gilvear and Willby 2006), others highlight the active role of vegetation in influencing river channel dynamics (e.g. Tal et al 2004;Corenblit et al 2007;Gurnell et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Riparian vegetation as indicator of channel adjustments and environmental conditions: the case of the Panaro River (Northern Italy)

et al. 2015

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Disturbances affecting flow and sediment transport regimes (e.g. dams, diversions, gravel mining, weirs, bank reinforcements, climate changes) can promote riverbed degradation and channel narrowing, and thus influence vegetation dynamics and composition. This study investigates the relationships and feedbacks between channel adjustments and riparian vegetation dynamics by combining an analysis of morphological channel changes with a wider phytosociology analysis of existing vegetation within the river corridor. These relationships were illustrated by using the case study of the Panaro River (located in the Northern Apennines, Italy), being a representative case of a deeply incised and narrowed river. More specifically we analyzed: (1) the relations between landforms and distributional patterns of vegetation types and characteristic plant species (index species): these provided information about the hydrogeomorphic condition of fluvial landforms and about channel adjustments; (2) the distance of riparian vegetation conditions from expected conditions as a consequence of human impact, based on the fact that each species and vegetation type has a given tolerance for specific disturbance regimes or stresses. Although some expected relations between landforms and vegetation types were found, we recorded significant deviations from the typical correlation pattern existing between morphology and vegetation, and this could be used to infer the intensity and the typology of human disturbances. In particular, the index species can indicate present ecological conditions and on past channel evolution. With this knowledge it might be possible to develop botanical recovery models in the future and, even more importantly, enable the recognition of the differences between temporal and spatial diversity.

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Channel instability as a control on silting dynamics and vegetation patterns within perifluvial aquatic zones

Cited by 92 publications

References 29 publications

Bifurcation instability and chute cutoff development in meandering gravel-bed rivers

Bifurcation instability and chute cutoff development in meandering gravel-bed rivers

Threshold behaviour in hydrological systems as (human) geo-ecosystems: manifestations, controls, implications

Riparian vegetation as indicator of channel adjustments and environmental conditions: the case of the Panaro River (Northern Italy)

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