Shear Stress Partitioning for Idealized Vegetated Surfaces

Thompson, Anita M.; Wilson, Bruce; Hansen, B.

doi:10.13031/2013.16102

Cited by 33 publications

(31 citation statements)

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“…The effects of vegetation on flow have been explored for submerged 405 vegetation Nepf, 2002, 2006;Jarvela, 2002;Liu et al, 2008;Nepf and Ghisalberti, 2008) and emergent vegetation (Nepf, 1999;Nepf and Vivoni, 2000;Jarvela, 2002;Thompson et al, 2004, Liu et al, 2008 when placed on the channel bed. This analysis was extended to examine the effects of vegetation on turbulence structure with vegetation on the floodplain (Thornton et al, 2000;McBride et al, 2007;Yang et al, 2007) and on the streamside (White and Nepf, 2007); however, the effects of vegetation on sloping streambanks have not been analysed.…”

Section: Introductionmentioning

confidence: 99%

Vegetation impacts on near bank flow

Hopkinson

Wynn

2009

Ecohydrology

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Vegetation is an important component of stream restoration designs used to control streambank retreat, but vegetation effects on near bank flows need to be quantified. The goal of this research was to evaluate how three-dimensional velocity structure and turbulence characteristics vary with three vegetation treatments: tree, shrub and grass. A second order prototype stream (Tom's Creek in Blacksburg, Virginia, USA) with individual reaches dominated by each vegetation treatment was modelled in a research flume using a fixed-bed Froude-scale modelling technique. One model streambank of the prototype stream was constructed for each vegetation type and compared to a bare control (only grain roughness). Velocity profiles perpendicular to the flume model boundary were measured using a three-dimensional acoustic Doppler velocimeter. Three-dimensional velocity records, turbulent kinetic energy characteristics, and Reynolds stresses were analysed. The addition of vegetation on a sloping streambank increased the free stream streamwise velocity as compared to a bare streambank. Velocity in the downstream direction decreased in the area close to the streambank boundary for all vegetation treatments. Tree turbulence intensity and Reynolds stress distributions were similar to the bare condition due to the sparse tree placement characteristic of mature forests. The turbulence caused by the upright shrub treatment increased turbulent kinetic energy and Reynolds stresses near the streambank, particularly at the toe. The flexible grass vegetation folded and protected the streambank, reducing shear stress near the boundary.

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Section: Introductionmentioning

confidence: 99%

Vegetation impacts on near bank flow

Hopkinson

Wynn

2009

Ecohydrology

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“…This was expected as soil erodibility parameters suggested highly erodible soil properties and also because the presence of heavy vegetation on the bank face, which can significantly decrease the applied τ reaching the detachable soil particles or aggregates [9,[51][52][53][54][55]. This highlights the need to account for the impact of vegetation or meanders on applied τ during model setup and calibration.…”

Section: Implications For Lateral Retreat Predictionmentioning

confidence: 88%

“…Applied τ can be impacted by the presence of meanders (increased τ) or bank face vegetation roots and/or above-ground biomass (decreased τ) [28,[51][52][53][54][55], which is not taken into account in the one-dimensional calculation of τ [9] in CONCEPTS. Because the model does not allow for the direct adjustment of τ, an ν-factor can be used to indirectly adjust τ by adjusting erodibility parameters as discussed in Langendoen et al [42] and Daly et al [37]:…”

Section: Adjusting Erodibility Parameters During Model Calibrationmentioning

confidence: 99%

Watershed Variability in Streambank Erodibility and Implications for Erosion Prediction

Enlow

Fox

Guertault

2017

Water

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Abstract:Two fluvial erosion models are commonly used to simulate the erosion rate of cohesive soils: the empirical excess shear stress model and the mechanistic Wilson model. Both models include two soil parameters, the critical shear stress (τ c ) and the erodibility coefficient (k d ) for the excess shear stress model and b 0 and b 1 for the Wilson model. Jet erosion tests (JETs) allow for in-situ determination of these parameters. JETs were completed at numerous sites along two streams in each the Illinois River and Fort Cobb Reservoir watersheds. The objectives were to use JET results from these streambank tests to investigate variability of erodibility parameters on the watershed scale and investigate longitudinal trends in streambank erodibility. The research also determined the impact of this variability on lateral retreat predicted by a process-based model using both the excess shear stress model and the Wilson model. Parameters derived from JETs were incorporated into a one-dimensional process-based model to simulate bank retreat for one stream in each watershed. Erodibility parameters varied by two to five and one to two orders of magnitude in the Illinois River watershed and Fort Cobb Reservoir watershed, respectively. Less variation was observed in predicted retreat by a process-based model compared to the input erodibility parameters. Uncalibrated erodibility parameters and simplified applied shear stress estimates failed to match observed lateral retreats suggesting the need for model calibration and/or advanced flow modeling.

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“…The proposed framework includes learning and pedagogy theory in combination with gaming requirements [5][6][7][8] and aims to establish a conceptual model that will be used by the game designer or educational practitioner when designing serious games for effective learning.…”

Section: Serious Games Conceptual Frameworkmentioning

confidence: 99%

“…Game mechanics and game rules define the details of the game [6]. If the game genre is a Real Time Strategy (RTS), for example, then it may require game mechanics of resource management and territory control.…”

Section: Game Mechanicsmentioning

confidence: 99%