1 INTRODUCTION
Wave climate plays a very important role in all coastal projects. However, in most
cases, little (if any) wave data are available for engineering construction and planning.
Field observation and physical modeling of waves are extremely difficult, costly, and time-
consuming. Buoys are far away from the project site, and remote-sensing instruments do
not systematically provide wave data at the desired resolution in the near shore region.
Since no data-recording instrument can anticipate future sea states, the desired sea-state
information may be obtained and plans evaluated with reliable mathematical modeling
techniques.
It is essential to have reliable information on wave conditions for many coastal and
ocean engineering problems.
The most important wave conditions for design and
assessment in project studies in the area of interest include the wave heights, wave periods
and the dominant wave propagation directions. Typically, these wave parameters are
obtained from a wave transformation model that transfers the wave data collected at some
remote deep water site to the location of the project in the near shore. As waves move
from deeper waters to approach the shore, these fundamental wave parameters will change
as the wave speed changes and wave energy is redistributed along wave crests due to the
depth variation between the transfer sites and the presence of islands, background
currents, coastal defense structures, and irregularities of the enclosing shore boundaries
and other geological features. Waves undergo the severest change inside the surf zone
where wave breaking occurs and in the regions where reflected waves from coastline and
structural boundaries interact with the incident waves.
Until recently, the linear wave ray theory was used for wave transformation by
tracing rays from deep water to the project site near shore.
The effects on wave
propagation of the wave height and direction along the wave crest are ignored in the ray
theory since this theory assumes that wave energy propagates only along a ray and thus,
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