Equivalent Roughness for Shallow Channels

Channel sections with different roughnesses along the water perimeter are often encountered in design problems. Typical design problems include partly lined canals and tunnels with different construction materials used at the bottom and the side. It is necessary to compute the equivalent roughness coefficient for any hydraulic computation in open channels and in channels with ice cover. Two formulas have been developed herein for the equivalent roughness coefficient in shallow open-channel flow.