Present-day use of an empirical wave prediction method

Abstract

Knowledge of the offshore wave climate is key to the design of coastal engineering structures and to the study of shoreline evolution. To date, the available wave data have been limited both in time and space; even though there are several options for obtaining wave data calculated using complex numerical models at basin scale, design issues can in some cases be solved by means of simpler models. This paper shows whether, under certain conditions and in an enclosed basin, an old empirical model can provide results that are good enough to determine the design condition necessary for engineering purposes. The empirical model chosen to answer this question is called Sverdrup– Munk–Bretschneider modified (SMB-X) and was developed based on the indications of the Shore Protection Manual. The model was applied to an area off the northern coast of Sicily (Italy). The results were compared with measurements from a wave buoy. To evaluate whether the model is an efficient tool to calculate the ‘design wave’, a statistical analysis of extreme events is necessary. Such an analysis was performed on the measured wave parameters, on the wave parameters calculated by the empirical model and on those calculated by two spectral models that are as easy to use as the SMB-X

Storm Energy Flux Characterization along the Mediterranean Coast of Andalusia (Spain)

“…For the estimation of the return period of the energy flux (P) of each storm class, the probability of exceedance was fitted with a modification of the Weibull Cumulative Distribution Function (CDF) described in [23,31]:…”

“…where w and u parameters that depend on the location under examination. Using the auxiliary variables X = 100 · ln(2.5 · P) and Y = 100 · ln [ln (1/F(P))] [23,31], in the coordinate system X, Y, the data points should lie on a straight line. Thus, the parameters of Equation (3) can be easily estimated by fitting those data points by means of the least-squares method.…”