The TUFLOW Bed Shear Equations are given as: 

Metric Units: 

where:

 = Density

 = Gravity

 = Velocity

 = Manning's n

 = Depth

Units are in N/m2

In US Customary Units, the total bed shear stress is given as: 

Where:

  = Specific weight of water

R = Hydraulic Radius

S = Energy Slope

Manning's Energy Grade Line Slope in English Units is given as: 

Where: 

 = Specific weight of water

R = Hydraulic Radius

S = Energy Slope

CME =1.486 in English units and 1.0 in SI units

Where: 

 = Density

 = Gravity

In channels where the width is 10 times greater than Depth (R), then (R) is taken is Depth ().

With substitution, we get: 


With cancellation and roundup, we get: 

Units are in lb/ft2


On this section: