Civil Engineering Department, Faculty of Engineering, Hormozgan University
One of the most important issues in the area of coastal structures design is determination of forces and loadings resulted from shallow water wave breaking. In the process of wave breaking, the subsequent particle motion is transformed from irrotational to rotational motion and due to this matter, vorticity and turbulence are generated and the sediment transport is affected by this phenomenon. Therefore, it is necessary to know about the location of wave breaking and other parameters such as the breaker height, breaker depth, etc. Over the last century, several formulas have been presented for predicting the wave breaking onset. These formulas depend on many parameters (e.g. seabed slope, water depth at the location of breaking, offshore wave height, etc.) that need to be known in order to obtain the desired wave breaking parameter (e.g. breaker height). In this study, some of the formulas for predicting wave breaking onset proposed in the recent decade are evaluated using the available laboratory data and it is tried to find out which formula is more suitable in different cases and conditions. A refinement process is carried out for choosing the appropriate data points out of all the available compiled laboratory data. The comparison is carried out in two phases. In the first one, the formulas are compared using all the data and in the second one, the comparisons are made based on the breaker type. These two phases yield to different outcomes. In the first phase, the formula proposed by Delavari et al. has the lowest values of bias, relative error, scatter index and root mean square error and the coefficient of determination of Goda’s formula is the highest. In the second phase, the data are categorized based on the plunging and spilling breaker types and the comparisons are made based on this categorization. The outcomes derived from the first phase are different from the ones derived from the second one.