Design wave height selection in intermediate-depth waters

Abstract Two methods are compared for selection of design wave height for maritime structures in intermediate-depth water. One is the Composite Weibull distribution (CWD) method by Battjes and Groenendijk (2000) and another is the breaker index method by Goda (1974). The former is found inappropriate for practical use because of its inherent tendency of underestimating maximum wave height in intermediate-depth waters. Underestimation is caused by its artificial setting of the Weibull shape parameter at k2 = 3.6. A sample calculation for the offshore significant waves with H1/3 = 8.3 m and T1/3 = Tm − 1,0 = 12.5 m is presented to compare H0.1% by the CWD method and H1/250 by the breaker index method to demonstrate their differences. The present paper discourages use of the CWD method in design works in intermediate-depth waters, and recommends the breaker index method instead.