Riparian vegetation controls on braided stream dynamics

Gran, Karen B.; Paola, Chris

doi:10.1029/2000wr000203

Cited by 348 publications

(343 citation statements)

References 25 publications

(26 reference statements)

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“…Ultimately, there is a need to understand how eco-hydromorphic processes generate observed patterns, and in turn how patterns influence processes. An example is the way in which vegetation and sediments interact to shape river channels and flow characteristics, and, in turn, vegetation recruitment and sediment transport (Gran and Paola, 2001;Gurnell and Petts, 2002). The ultimate aim is to achieve a causal understanding of how the components of the ecologyhydrology-geomorphology interface interact.…”

Section: Process and Causalitymentioning

confidence: 99%

Integrating ecology with hydromorphology: a priority for river science and management

Vaughan¹,

Diamond²,

Gurnell³

et al. 2007

Aquatic Conservation

282

217

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ABSTRACT1. The assessment of links between ecology and physical habitat has become a major issue in river research and management. Key drivers include concerns about the conservation implications of human modifications (e.g. abstraction, climate change) and the explicit need to understand the ecological importance of hydromorphology as prescribed by the EU's Water Framework Directive. Efforts are focusing on the need to develop 'ecohydromorphology' at the interface between ecology, hydrology and fluvial geomorphology. Here, the scope of this emerging field is defined, some research and development issues are suggested, and a path for development is sketched out.2. In the short term, major research priorities are to use existing literature or data better to identify patterns among organisms, ecological functions and river hydromorphological character. Another early priority is to identify model systems or organisms to act as research foci. In the medium term, the investigation of patternprocesses linkages, spatial structuring, scaling relationships and system dynamics will advance mechanistic understanding. The effects of climate change, abstraction and river regulation, eco-hydromorphic resistance/ resilience, and responses to environmental disturbances are likely to be management priorities. Large-scale catchment projects, in both rural and urban locations, should be promoted to concentrate collaborative efforts, to attract financial support and to raise the profile of eco-hydromorphology.3. Eco-hydromorphological expertise is currently fragmented across the main contributory disciplines (ecology, hydrology, geomorphology, flood risk management, civil engineering), potentially restricting research and development. This is paradoxical given the shared vision across these fields for effective river management based on good science with social impact. A range of approaches is advocated to build sufficient, integrated capacity that will deliver science of real management value over the coming decades.

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Section: Process and Causalitymentioning

confidence: 99%

Integrating ecology with hydromorphology: a priority for river science and management

Vaughan¹,

Diamond²,

Gurnell³

et al. 2007

Aquatic Conservation

282

217

View full text Add to dashboard Cite

show abstract

“…Where vegetation has been incorporated, the focus has been largely on aquatic vegetation and, particularly, on the ways in which it affects the flow field (e.g., Folkard, 2009;Nikora, 2010;Nepf, 2012) and associated sediment dynamics. Riparian vegetation has also been incorporated into flume experiments, for example, illustrating how it is a crucial ingredient for reproducing single thread / meandering rivers (Gran and Paola, 2001;Paola, 2007, 2010;Braudrick et al, 2009;van Dijk et al, 2013). …”

Section: Introductionmentioning

confidence: 99%

“…For example, vegetation impacts can be investigated at both fine scales, such as the contribution of root reinforcement to bank cohesion, and at coarser scales, such as the retention of sediment by vegetation to build islands (e.g. Gran and Paola, 2001;Perona et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Physical modelling of the combined effect of vegetation and wood on river morphology

et al. 2015

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The research reported in this paper employs flume experiments to investigate the potential effects of living vegetation and large wood on river morphology, specifically aiming to explore how different wood input and vegetation scenarios impact channel patterns and dynamics.We used a mobile bed laboratory flume, divided into three parallel channels (1.7 m wide, 10 m long) filled with uniform sand to reproduce braided networks subject to a series of cycles of flooding, wood input, and vegetation growth. Temporal evolution of river configuration (in terms of the braiding index), vegetation establishment and erosion, and wood deposition amount and pattern was recorded in a series of vertical images. The experiments reproduced many forms and processes that have been observed in the field, from scattered logs in unvegetated, dynamic braided channels, to large wood jams associated with river bars and bends in vegetated, stable, single thread rivers. Results showed that the inclusion of vegetation in the experiments changes wood dynamics, in terms of both the quantity that is stored and the depositional patterns that develop. Vegetated banks increased channel stability, reducing lateral erosion and the number of active channels. This promoted the formation of stable wood jams, where logs accumulated continuously at the same locations during subsequent floods, reinforcing their effect on river morphology. The feasibility of studying these processes in a controlled environment opens new possibilities for disentangling the complex linkages in the biogeomorphological evolution of the fluvial system and thus for promoting improved scientific understanding.

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“…Instead, in such experiments, the channel simplifies to a single bend following cutoffs (16), or bank migration ceases once sinuosity develops (15). Recently, alfalfa sprouts have been used to provide bank strength in experimental channels (17)(18). Adding alfalfa sprouts to braided flume channels transformed them into dynamic channels with characteristics of both singlethread and island-bar morphology.…”

mentioning

confidence: 99%

Experimental evidence for the conditions necessary to sustain meandering in coarse-bedded rivers

Braudrick

Dietrich

Leverich

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

321

353

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Meandering rivers are common on Earth and other planetary surfaces, yet the conditions necessary to maintain meandering channels are unclear. As a consequence, self-maintaining meandering channels with cutoffs have not been reproduced in the laboratory. Such experimental channels are needed to explore mechanisms controlling migration rate, sinuosity, floodplain formation, and planform morphodynamics and to test theories for wavelength and bend propagation. Here we report an experiment in which meandering with near-constant width was maintained during repeated cutoff and regeneration of meander bends. We found that elevated bank strength (provided by alfalfa sprouts) relative to the cohesionless bed material and the blocking of troughs (chutes) in the lee of point bars via suspended sediment deposition were the necessary ingredients to successful meandering. Varying flood discharge was not necessary. Scaling analysis shows that the experimental meander migration was fast compared to most natural channels. This high migration rate caused nearly all of the bedload sediment to exchange laterally, such that bar growth was primarily dependent on bank sediment supplied from upstream lateral migration. The high migration rate may have contributed to the relatively low sinuosity of 1.19, and this suggests that to obtain much higher sinuosity experiments at this scale may have to be conducted for several years. Although patience is required to evolve them, these experimental channels offer the opportunity to explore several fundamental issues about river morphodynamics. Our results also suggest that sand supply may be an essential control in restoring self-maintaining, actively shifting gravel-bedded meanders.channel patterns ͉ fluvial geomorphology ͉ river meandering R iver meandering-the lateral bank shifting that produces sinuous, single-thread channels-is inherent to coupled flow and sediment transport in gravel-and sand-bedded channels within a broad range of channel width-to-depth ratios (1). Channel planform classification based on field observations qualitatively suggests that meandering depends strongly on channel slope, grain size, bank strength, and sediment supply (2, 3). Theoretical models of river meandering (2-8), however, assume that the inner and outer banks migrate at the same rate during meandering no matter the bank strength and sediment supply. The processes by which inner bank deposition keeps pace with outer bank erosion are poorly known. This is a fundamental gap in our understanding of meandering rivers.Laboratory experiments have demonstrated that channels with sand or gravel bed and banks will develop bars and planform curvature but will inevitably braid (9-11), because the weak outer banks erode faster than bars can grow and accrete to the inner bank. Braiding often develops due to flow diversion down chutes that form between the bar and the floodplain. Chutes occur because the area of maximum coarse sediment deposition is not located at the boundary between the bar and floodplain, but rather t...

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Riparian vegetation controls on braided stream dynamics

Cited by 348 publications

References 25 publications

Integrating ecology with hydromorphology: a priority for river science and management

Integrating ecology with hydromorphology: a priority for river science and management

Physical modelling of the combined effect of vegetation and wood on river morphology

Experimental evidence for the conditions necessary to sustain meandering in coarse-bedded rivers

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