Nearshore processes

As wind‐generated waves propagate from the deep ocean toward the shore, the decreasing depths begin to influence near‐bottom orbital motions, modifying the wave kinematics. Through the resulting nonlinearities, energy is transferred from typical ocean periods of order 10 seconds to both lower and higher frequencies, until local spectra bear little resemblance to the offshore energy input. In turn, orbital velocities can cause transport of unconsolidated bottom sediments that may eventually result in changes in the beach topography. Thus, the nearshore system is usually considered composed of two components; the fluid forcing and the sediment response. At short time scales, the mobility of the sediment bed is considered to have negligible effect on the fluid dynamics and each component of the problem can be considered separately (i.e. fluid dynamics over a measured topography, and sediment transport under a measured local wave field). At longer scales, changes in bottom bathymetry can be substantial; the feedback between the two component can have a fundamental influence on system behavior.