Roughness of Loose Rock Riprap on Steep Slopes

Rice, Charles E.; Kadavy, Kem C.; Robinson, K. M.

doi:10.1061/(asce)0733-9429(1998)124:2(179)

Cited by 74 publications

(42 citation statements)

References 5 publications

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“…The model is also compared with the empirical formulae specific to rough ramps (Table 2), in particular, the work of [1] with hemispherical macro-roughnesses, which are put on pebbles of characteristic size k s = 0.019 m. The formulae from [5,7] are also assessed since they are used frequently. These relationships do not depend on concentration since the obstacles are assumed to be in contact.…”

Section: Input Parametersmentioning

confidence: 99%

“…, and C f is the bed friction coefficient obtained from the formula given by [7,26]. As no bed friction in the wake of an element is considered, α is lower than 1 − Γ.…”

Section: Emergent Roughness Elementsmentioning

confidence: 99%

“…To mitigate these problems, many studies have sought to describe experimentally how friction changes with water depth, slope, or Froude number. However, the formulations set out often seem to be limited to their particular domains of investigation [5][6][7] and rarely allow treatment of flow over beds that may be emergent, confined, or completely submerged. Such significant variations in water depth or slopes are common in models of fish habitat, floodplains, or mountain rivers.…”

Section: Introductionmentioning

confidence: 99%

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A Semi-Analytical Model for the Hydraulic Resistance Due to Macro-Roughnesses of Varying Shapes and Densities

Cassan

Roux

Garambois

2017

Water

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A friction model resulting from investigations into macro-roughness elements in fishways has been compared with a broad range of studies in the literature under very different bed configurations. In the context of flood modelling or aquatic habitats, the aim of the study is to show that the formulation is applicable to both emergent or submerged obstacles with either low or high obstacle concentrations. In the emergent case, the model takes into account free surface variations at large Froude numbers. In the submerged case, a vegetation model based on the double-averaging concept is used with a specific turbulence closure model. Calculation of the flow in the roughness elements gives the total hydraulic resistance uniquely as a function of the obstacles' drag coefficient. The results show that the model is highly robust for all the rough beds tested. The averaged accuracy of the model is about 20% for the discharge calculation. In particular, we obtain the known values for the limiting cases of low confinement, as in the case of sandy beds.

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Section: Input Parametersmentioning

confidence: 99%

“…, and C f is the bed friction coefficient obtained from the formula given by [7,26]. As no bed friction in the wake of an element is considered, α is lower than 1 − Γ.…”

Section: Emergent Roughness Elementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Semi-Analytical Model for the Hydraulic Resistance Due to Macro-Roughnesses of Varying Shapes and Densities

Cassan

Roux

Garambois

2017

Water

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“…N is the ratio between bed friction force and drag force, a is the ratio of the area where the bed friction occurs on a x Â a y and s is the ratio between the block area in the x, y plane and D 2 (for a cylinder s = p/4), C f is the bed friction coefficient from Rice et al (1998) (Cassan et al, 2014). C f is calculated by:…”

Section: 3mentioning

confidence: 99%

Design of emergent and submerged rock-ramp fish passes

Cassan

Laurens

2016

Knowl. Manag. Aquat. Ecosyst.

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-An analytical model is developed to calculate the stage-discharge relationship for emergent and submerged rock-ramp fish passes. A previous model has been modified and simplified to be adapted to a larger range of block arrangement. For submerged flows, a two-layer model developed for aquatic canopies is used. A turbulent length scale is proposed to close the turbulence model thanks to a large quantity of data for fully rough flows from the literature and experiments. This length scale depends only on the characteristic lengths of arrangements of obstacles. Then the coefficients of the logarithmic law above the canopy can also be deduced from the model. As a consequence, the total discharge through the fish pass is computed by integrating the vertical velocity profiles. A good fit is found between the model and commonly observed values for fish pass or a vegetated canopy. The discharge of the fish pass is then accurately estimated for a large range of hydraulic conditions, which could be useful for estimating fish passability through the structure.

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“…In a study on sloping weir, Rice et al [5] conducted an experiment on riprap placed loosely on top of a sloping waterway. This study proposed a new formula by combining the relationship with roughness coefficient proposed by Manning and Darcy-Weibach with experiment data from Abt et al…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Flow Characteristic in Sloping Weir

Kang¹,

Kim²,

Yeo³

et al. 2014

ENG

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Drop structure is a key hydraulic structure used in river improvement projects for flood control purposes. However, as demand for riparian construction techniques with environmental considerations is increasing both domestically and internationally, discontinuation of aquatic organisms as a result of high head is raised as a serious issue associated with the existing drop structures. Accordingly, it has become necessary to install a drop structure with a mild slope rather than the existing drop structures with high head, so that the structure can function as a migration channel for fish, which is severed by the existing drop structures, and also improve surrounding landscapes. In this study, which was initiated based on the necessity as such, a drop structure of mild slope was defined as sloping weir and flow characteristics under different conditions were analyzed through a hydraulic experiment. Focusing on efficiency according to energy dissipation that takes place according to different gradients of sloping weir, particle sizes of riverbed materials and the effect of hydraulic jump occurring at the downstream of a structure, this study aimed at identifying flow characteristics according to the conditions of sloping weirs. The hydraulic experiment was carried out on a variable-slope channel measuring 0.6 m in width and 20.0 m in length. As for riverbed materials, materials with two particle sizes (16 mm and 25 mm) were selected. For the experiment, models with different slope ratios to the structure, such as 1V:2H, 1V:3H and 1V:4H, were created. For flow conditions and hydraulic jump locations, an amount of water satisfying four water level conditions by stage was flown according to water level at the inlet area. Then, eight points were selected from inlet area, drop area, jet flow area and downstream area by controlling water level at the downstream area and adjusting the location of hydraulic jump occurrence. Water level (y), flow velocity (V), length of hydraulic jump (Lr) and distance of hydraulic jump occurrence (L j ) were measured at the eight points.

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Roughness of Loose Rock Riprap on Steep Slopes

Cited by 74 publications

References 5 publications

A Semi-Analytical Model for the Hydraulic Resistance Due to Macro-Roughnesses of Varying Shapes and Densities

A Semi-Analytical Model for the Hydraulic Resistance Due to Macro-Roughnesses of Varying Shapes and Densities

Design of emergent and submerged rock-ramp fish passes

Experimental Study on Flow Characteristic in Sloping Weir

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