Development of empirical regression-based models for predicting mean velocities in asymmetric compound channels

• Asymmetric rectangular compound cross sections channels were investigated.
• The geometry effect on different mean velocities was investigated.
• Regression analysis was used in the prediction of mean velocities.
• The different mean velocities were generalized with high accuracy.

In this paper, the authors present experimental results of overbank flow in asymmetric rectangular compound channels considering both smooth and rough flumes. The mean velocity distributions in the main channel, floodplain, and the whole cross-section were measured for nine different test models constructed with variable main channel width and step height. The mean velocity measurements are then related to a dimensionless parameter called the relative depth defined as the ratio of the depth above the floodplain bed to the depth above the main channel bed. The variations and interactions of the three outlined mean velocities have been investigated with respect to relative depth. A set of single-variable regression models has been developed for estimating the three mean velocity types using relative depth as the only independent variable. Another set of multiple-variable regressions models has been derived using two additional dimensionless parameters which take into account the width dimensions of the constructed asymmetric compound channel. The application of several key statistics and validation procedures has indicated the high significance and reliability of the developed models in predicting the three mean velocity types. The predicted mean velocities can then be used to estimate the corresponding channel flow rate using the continuity equation.