Stage-Discharge Prediction for Converging Compound Channels with Narrow Floodplains

Momentum transfer between the main channel and the side flood plains tends to increase the floodplain shear whereas the main channel shear decreases. The increase and decrease in shear are greatly influenced when a compound channel is with non-prismatic flood plains. In converging compound channels water flow on the floodplain crosses over water flow in the main channel, resulting in increased interactions and momentum exchanges. An experimental analysis concerning the distribution of shear stress in the main channel and floodplain for both prismatic and non-prismatic compound channels under different over-bank flow conditions are performed. New equations are developed for predicting boundary shear stress distribution for a compound channel with the non-prismatic flood plain. Using these expressions the stage-discharge relationships for both prismatic and non-prismatic compound channels of lower width ratio have been successfully estimated. The efficiency of the models has also been verified by applying natural river data sets. Author