Rediscovering significant wave height and the roots of coastal engineering thinking

摘要

This discussion presents insight into some of the most basic concepts and premises of coastal engineering which have lost physical significance - or worse, have been allocated undeserving attributes because of the pure application of mathematical calculations without regard to the associated physics. The most classic example is the misuse of the "significant wave height." The discussion extends further into understanding how these false attributes can lead to serious errors in design. Breakwaters are designed using values of hindcasted significant wave heights substituted into stability formulas developed from monochromatic waves; sediment transport rates are computed for single value wave heights as if that value represents every wave in a storm; wave period sensitive phenomena such as refraction and diffraction, or even the response of floating objects are oversimplified because the effect of a single representative wave period is assumed to describe the full behavior of the sea. In this paper, these same common coastal engineering parameters and relationships are explored to discover how the physics of the nearshore actually work and how that understanding can be used to cure many coastal maladies.