1.Manning Equation

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1.Manning Equation
V R 2/3 S 1/2 n
Where v average flow velocity r hydraulic
radius s channel slope (unitless) n Manning
roughness coefficient
R A/P A Area P Wetted Perimeter

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1.Manning Equation
For the South River S 0.0009 n 0.04
Q 1.49AR 2/3 S 1/2 n
Where Q average flow velocity (ft3/s) R
hydraulic radius (ft) S channel slope
(unitless) n Manning roughness coefficient
R A/P A Area (ft2) P Wetted
Perimeter (ft)
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A. Sediment Transport 1. Shear Stress
tc hc ?w g S
Shields Equation
tc tc (?s ?)gD50
tc critical boundary shear stress ?s, ?w
grain density (assume 2.65 g/cm3) and water
density g gravitational acceleration (981
cm/s2) D50 median bed material grain size
tc dimensionless critical shear stress (the
Shields number) (0.03 for sand 0.047 for
gravel/cobble)
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A. Sediment Transport 2. Critical Flow
Depth
tc hc (?wgS)
hc critical flow depth to mobilize
sediment tc critical boundary shear
stress ?w water density g gravitational
acceleration (981 cm/s2) S Average bed slope