Revisiting the derivation of bulk longshore sediment transport rates using meta-heuristic algorithms

During recent decades, different formulas have been developed to estimate longshore sediment transport rates through calibration using a wide variety of datasets, applicable for a range of particular wave and beach conditions. The equations that have shown the best capability to predict Bulk Longshore Sediment Transport Rate (BLSTR) are the formulas derived by CERC and by Kamphuis. In the present study, the five process parameters as used in the Kamphuis formula are accepted. The CERC formula includes only two of the five process parameters used in Kamphuis’ formula. A renewed optimization to derive the power of the five Kamphuis’ process parameters using an extensive dataset by Bayram was performed by Mil-Homens. In addition to this valuable effort, our contribution introduces two innovations. Firstly, the power coefficients of the five Kamphuis process parameters are optimized using a broad range of meta-heuristic algorithms. Secondly, the optimization is not based on the Bayram dataset as carefully collected and reviewed from published manuscripts but on a methodologically more homogeneous Iranian dataset acquired for port design and port management purposes. Independently from the results by Mil-Homens derived from the Bayram dataset, our study confirms these findings based on a totally different dataset. Specifically, the weaker impact of wave period and the stronger impact of the median grain diameter are in accordance with each other. The latter finding provides a stronger support for the mutual cancellation of the impact of slope and grain diameter in BLSTR, lending explanatory support to the CERC formula once beach slope and grain size are not known