Discrepancies in Design Wave Based on Source and Location of Wave Data

The determination of design wave height is fundamental to most coastal and ocean engineering applications. While the design wave height analysis and selection may appear to be a straightforward and routine analysis, significant discrepancies in results can occur based on the original data source used as well as extremal analysis techniques utilized. The availability and quality of wave data for use in coastal and oceanographic studies is a common initial hurdle for most applications. If wave data is available at all, it can be available in a wide variety of forms and periods of record. This paper will investigate the implications of the various wave data sources on resultant design wave climate determination. Extremal analysis techniques are also evaluated. Results presented herein show that reliance on deepwater buoys to define transitional depth wave climate may underestimate extreme wave heights. Wave Information Study Phase II data provide lower design wave estimates by as much as 3 to 4 meters. Nearshore wave estimates along the Oregon coast are higher by 3 meters compared to the northern Oregon coast. Selection of the storm threshold in the Peak-Over-Threshold method of extremal analysis significantly affects the results.