Discussion: Comparative study of breakwater crown wall – calculation methods

Abstract

Contribution by Jorge Molines This paper (Negro Valdecantos et al., 2013) presents an extensive and useful comparison of existing formulas to estimate wave forces on crown walls. The paper also provides valuable insights into crown wall behaviour, suggesting the use of formulas for prior sizing and recommending, in any case, tests on a physical model in order to confirm the final design. The authors helpfully advise to use more than one method to obtain results closer to reality, always taking into account the test conditions under which each formula was developed.

Overtopping layer thickness and overtopping flow velocity on mound breakwaters

“…Table 10 shows the median rMSE on measured logQ and dimensionless wave forces using Eqs. (13), (16), (18), (19) and 21with overtopping predictions given by Eqs. (1) to (6) and the CLASH Neural Network.…”

“…Several prediction methods are given in the literature to calculate wave forces on crown walls, usually associated with a 0.1% probability of exceedance (see Negro et al [18]); however, these methods show significant discrepancies (see Molines [19] and Negro et al [5]). USACE [20] described the methods reported by Jensen [21] and Pedersen [2] to evaluate wave forces on crown walls.…”

“…The far right column in Table 10 shows the median rMSE of predicted wave forces and moments on the crown wall using the I1H7O1 model (test data) used to develop Eqs. (13), (16), (18), (19) and (21). The CLASH Neural Network provided the best overtopping estimations for Pedersen [2] and Molines [8] data, and the best wave force and overturning moment estimations based on wave overtopping.…”

“…Eqs. (13), (16), (18), (19) and (21) allow for an easy estimation of wave forces on crown walls based on logQ and Fc/L0p. They make it clear that higher dimensionless overtopping rates inevitably generate higher dimensionless wave forces on crown walls.…”

Editorial

“…We also welcome a discussion (Negro Valdecantos et al, 2014) of one of our previously published papers: Comparative study of breakwater crown wall -calculation methods (Negro Valdecantos et al, 2013). The contributors add to the information provided in the original paper by identifying further work since available that could assist those working in this field.…”