On the recession of berm breakwaters

Abstract

Berm breakwaters are coastal structures with a rather wide armor layer made of a wide range of stone sizes. These structures are allowed to reshape in response to wave action and as a result, become more stable. Prediction of berm breakwaters' recession is one of the most important tasks in the design of berm breakwaters. Hence, several experimental studies have been carried out on the stability of berm breakwaters and several formulas for predicting the recession are obtained based on them. First, the existing databases were scrutinized to provide a comprehensive databank. Then, it was used to develop a new formula for the berm recession, which includes effects of most important structural characteristics such as front slope, berm height, armor size, density and grading as well as sea state parameters such as wave height, wave period, and water depth. The proposed formula's physical reasoning and accuracy metrics indicated that it outperforms existing formulas, especially in the practical range, i.e., shallow waters with recession between 0.5 and 10 times the armour size. A sensitivity analysis of the Sirevåg berm breakwater was conducted to illuminate the performance of various formulas and the influence of different parameters, Additionally, design recommendations are provided for practitioners.