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5.1: Introduction

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    This chapter deals with the near-shore hydrodynamics that are important for sediment transport. It treats mean and oscillatory water levels and currents induced by waves, wind and tides. Relatively a lot of attention is paid to waves and wave-induced currents because of their effectiveness in transporting sediment in the surf zone.

    The following aspects of waves are described:

    • Linear wave propagation effects in shoaling waves (until wave breaking): increasing wave heights, decreasing wavelengths and refraction towards normal incidence (Sect. 5.2);
    • Non-linear transformation of the wave shapes from initially symmetric, sinusoidal profiles, to asymmetric, pitched forward profiles characteristic of near- breaking waves (Sect. 5.3);
    • Wave dissipation in the wave boundary layer and its effect on wave-orbital velocities, bed shear stress and net wave-induced flow (called Longuet-Higgins streaming) close to the bed (Sect. 5.4);
    • Wave-induced water level changes in breaking waves such as the set-up (raising of the water level) at the coast, and wave-induced flow in breaking waves: a circulation current in the cross-shore direction (within the lower part of the water column an offshore directed undertow) as well as a longshore current along the coast (Sect. 5.5).

    Subsequently Sect. 5.5 describes wind-generated set-up and currents. Section 5.7 is dedicated to tidal propagation in coastal waters. Last, Sect. 5.8 discusses some other long wave phenomena in coastal waters, viz. seiches and surf beat.

    This page titled 5.1: Introduction is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Judith Bosboom & Marcel J.F. Stive (TU Delft Open) via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.