Transformation of Monochromatic Waves from Deep to Shallow Water

Source: https://erdc-library.erdc.dren.mil/jspui/ Prediction of nearshore wave characteristics is an essential part of any study dealing with the determination of littoral transport or longshore currents. Since it is more efficient to determine the deepwater wave as opposed to in shallow water where many points are needed because of bottom effects, it is necessary to transform those deepwater values into shallow-water characteristics. This study reviews the state-of-the-art techniques for transformation of monochromatic surface gravity waves from deep to shallow water over a varying bathymetry. Nonlinear effects are considered and particular emphasis is put on the determination of breaking wave characteristics. For a plane sloping bottom, a new "hybrid" wave theory is introduced which gives improved results for breaking characteristics as compared with existing theories. This hybrid theory uses cnoidal wave height transformation and linear wavelength transformation. Nomographs are presented for easy determination of breaking wave angles and other characteristics such as depth, wave height, and wavelength from given deepwater characteristics and bottom slope.