ABSTRACT
A "wave" is the generic term for any (periodic) fluctuation in water height, velocity or pressure. This chapter will be restricted to wind-generated waves. The term sea is often used for "fresh" waves, where the driving wind force is still active, in contrast to swell. Swell is the name for waves that were caused by wind, but possibly long ago (days) and far away on the ocean (thousands of km), travelling on with the, slowly dissipating, energy gained from the wind. For the pressures and velocities in non-breaking, short waves, the linear wave theory is a valuable and comprehensive tool to get an idea of orders of magnitude and of the influence of parameters such as wave height, period, water depth etc. Wave heights are limited due to breaking. Wave load reduction is possible with various devices e.g. dams, screens, floating breakwaters etc. For an effective wave reduction, these structures must have large dimensions compared with water depth or wavelength.
