Channel maximum shear stress can be used in selecting different linings for channels. Channel maximum shear stress is calculated from unit weight of water, depth of flow in channel and channel bottom slope. The software calculates and displays channel maximum shear stress and maximum depth in the SWMM engine, SewerGEMS Dynamic Wave engine, and GVF Rational engine calculation.

Channel Maximum shear stress is given by:

τ_d = γdS_o

where:

τ_d = shear stress in channel at maximum depth, N/m2 (lb/ft2 )

γ = unit weight of water, N/m3 (lb/ft3 )

d = depth of flow in channel, m (ft)

S_o = channel bottom slope, m/m (ft/ft)

For calculating channel maximum shear stress, channel maximum depth is needed. For the SWMM and GVF Rational engines, the maximum depth at channel start and stop sections at all time steps is used. For the SewerGEMS Dynamic Wave engine, the maximum depth at channel start, stop, and middle sections is used.

Result Fields

Shear Stress (Maximum): Shear Stress corresponding to the Depth (Maximum).

Depth (Maximum): Maximum depth in the channel determined by comparing depths at each end of he channel(start and stop) and the middle of channel across all time steps.