Model development for energy dissipation over gabion stepped weirs using GEP and GMDH techniques

A gabion stepped weir is a permeable weir that consists of a gabion box fllled with stone aggregates. It is cost-effective structure used for the dissipation of water flow energy from upstream to downstream. Gabion weir also allows the movement of aquatic life and transportation of physical and chemical substances present in water. In this study, energy dis-sipation in terms of inverse relative energy dissipation (IRED) over gabion stepped weir has been studied. It was observed that the existing predictor does not give a reasonable estimate for IRED. Therefore, the data have been reanalysed to develop a generalized regression equation for IRED. Generalized models using Gene Expression Programming (GEP) and Group Method of Data Handling (GMDH) were also developed. The predictions based on GMDH model (R = 0.979, E = 0.96 and RMSE = 0.314) were found more satisfactory than those given by traditional regression equations (R = 0.929, E = 0.91 and RMSE = 0.557) as well as those given by the GEP model (R = 0.959, E = 0.94 and RMSE = 0.476). Sensitivity analysis shows that the Froude number before the jump is the most important parameter for the prediction of IRED.