Bed load sediment transport in sewers at limit of deposition

Sedimentation is a problematic issue concerning sewer system design. In order to reduce sediment deposition in sewer systems, two new equations are presented with a smoothing function and Group Method of Data Handling (GMDH) to estimate minimum ow velocity. For this purpose, dimensional analysis is used to determine the factors aecting sediment transport at limit of deposition. These factors are categorized in ve dierent groups: transport, transport mode, ow resistance, sediment, and motion. Six dierent models are presented for predicting the densimetric Froude number (Fr) using the smoothing function and GMDH. The models presented with these two methods are compared with existing equations. The results indicate that the equations proposed using the smoothing function (MAPE = 5.05, RMSE = 0.24, and AIC = ??43.04) and GMDH (MAPE = 5.39, RMSE = 0.3, and AIC = 72.78) are more accurate than existing models. Furthermore, sensitivity analysis is performed to examine the ecacy of each of the dimensionless parameters presented by the best model in estimating Fr.