Flow resistance of emergent vegetation

James, C. S.; Birkhead, A. L.; Jordanova, A. A.; O’Sullivan, John

doi:10.1080/00221686.2004.9728404

Cited by 113 publications

(71 citation statements)

References 8 publications

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“…In hydraulic models, vegetation induced roughness is very often expressed in terms of the Manning's coefficient through the Manning's equation for uniform flow [40][41][42]. Although it was stated that Manning's equation might be inappropriate in cases where the drag force is dominant over the bed friction [43], at the reach scale, the results are reliable [44,45]. Therefore, it is a widely accepted methodology in stream resistance evaluation, especially in vegetated areas [46] and was successfully incorporated in numerous studies investigating impact of vegetation on water flow, depth and velocity [47,48].…”

Section: Introductionmentioning

confidence: 81%

Model-Based Analysis of Macrophytes Role in the Flow Distribution in the Anastomosing River System

Marcinkowski

Kiczko

Okruszko

2018

Water

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Abstract:The impact of vegetation on the hydrology and geomorphology of aquatic ecosystems has been studied intensively in recent years. Numerous hydraulic models developed to date help to understand and quantitatively assess the influence of in-stream macrophytes on a channel's hydraulic conditions. However, special focus is placed on single-thread rivers, leaving anastomosing rivers practically uninvestigated. To fill this gap, the objective of this study was to investigate the impact of vegetation on flow distribution in a complex anastomosing river system situated in northeastern Poland. The newly designed, one-dimensional, steady-flow model, dedicated for anastomosing rivers used in this study indicated high influence of vegetation on water flow distribution during the whole year in general, but-as expected-significantly higher in the summer season. Simulations of in-stream vegetation removal in selected channels reflected in Manning's coefficient alterations caused relatively high discharge transitions during the growing season. This proved the significance of feedback between process of plants growth and distribution of flow in anabranches. The results are unique and relevant and could be successfully considered for the protection of semi-natural anabranching rivers.

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Section: Introductionmentioning

confidence: 81%

Model-Based Analysis of Macrophytes Role in the Flow Distribution in the Anastomosing River System

Marcinkowski

Kiczko

Okruszko

2018

Water

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“…Figures 10 and 11 show that the surface area additionally caused by the leaves significantly increases the momentum absorbing area of plants, so as presented by James et al (2004), the leaves increase the value of n clearly and the influence of leaves on increases with the increasing flow depth. When the foliage condition is different, the results calculated by Eq.…”

Section: The Influence Of Leaf Area On Unsubmerged Conditionsmentioning

confidence: 87%

“…A similar formula is presented by Kutija and Hong (1996) and James et al (2004) The values of the drag coefficient C d for the long circular cylinders can be proposed by Schlichting (1962) as…”

Section: Analysis Of Influence Of Mean Vegetation Density On Unsubmermentioning

confidence: 88%

“…On the assumption made by Gu (2005, 2007), the measured Manning's n shows that the independence on flow velocity and the linear relationships can be well assumed between and flow depth. Moreover, the surface area additionally caused by the leaves significantly increases the momentum absorbing area of plants, so as presented by James et al (2004), the leaves increase the value of n clearly and the influence of leaves on n increases with the increasing flow depth.…”

Section: Analysis Of Influence Of Mean Vegetation Density On Unsubmermentioning

confidence: 93%

“…On the other hand, some researchers dropped the influence of characteristics of vegetation from their analysis and tried to make relatively common conclusions. Generally they conducted experiments with replicas of some species of vegetation made to scale the biomechanical properties from real vegetation, such as Carollo and Ferro et al (2002), Ni and Gu (2005, 2007, and Wilson et al (2003), or with real vegetation directly, such as Petryk and Bosmajian (1975), Jarvela (2005) and James et al (2004).…”

Section: Introductionmentioning

confidence: 99%

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Study on roughness coefficient for unsubmerged reed in the Changjiang Estuary

Lin

et al. 2011

Acta Oceanol. Sin.

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The influence of density, foliage and stem flexibility on the roughness coefficients under unsubmerged conditions, such as Manning's n, is investigated experimentally. An instrumentation system has been developed for measuring the flow rate ranging from 0.1 to 0.3 L/s under the condition of different artificial foliated reeds. Based on the experimental results, the influence on the relationship between n with different density, foliage, flexibility and flow depth is discussed. It is found that the foliage and the density are the important factors affecting Manning's n. At a range of relatively low velocity and relatively large bending stiffness of stem, Manning's n is not influenced significanthy by the flexibility of stem.

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Flow and scour constraints on uprooting of pioneer woody seedlings

Bywater‐Reyes

Wilcox

Stella

et al. 2015

Water Resources Research

112

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Scour and uprooting during flood events is a major disturbance agent that affects plant mortality rates and subsequent vegetation composition and density, setting the trajectory of physical‐biological interactions in rivers. During flood events, riparian plants may be uprooted if they are subjected to hydraulic drag forces greater than their resisting force. We measured the resisting force of woody seedlings established on river bars with in situ lateral pull tests that simulated flood flows with and without substrate scour. We quantified the influence of seedling size, species (Populus and Tamarix), water‐table depth, and scour depth on resisting force. Seedling size and resisting force were positively related with scour depth and water‐table depth—a proxy for root length—exerting strong and opposing controls on resisting force. Populus required less force to uproot than Tamarix, but displayed a greater increase in uprooting force with seedling size. Further, we found that calculated mean velocities required to uproot seedlings were greater than modeled flood velocities under most conditions. Only when plants were either shallowly rooted or subjected to substrate scour (≥0.3 m) did the calculated velocities required for uprooting decrease to within the range of modeled flood velocities, indicating that drag forces alone are unlikely to uproot seedlings in the absence of extreme events or bar‐scale sediment transport. Seedlings on river bars are most resilient to uprooting when they are large, deeply rooted, and unlikely to experience substrate scour, which has implications for ecogeomorphic evolution and river management.

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Flow resistance of emergent vegetation

Cited by 113 publications

References 8 publications

Model-Based Analysis of Macrophytes Role in the Flow Distribution in the Anastomosing River System

Model-Based Analysis of Macrophytes Role in the Flow Distribution in the Anastomosing River System

Study on roughness coefficient for unsubmerged reed in the Changjiang Estuary

Flow and scour constraints on uprooting of pioneer woody seedlings

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