MATHEMATICAL MODEL FOR WAVE DEFORMATION IN SHOALING WATER AND DETERMINATION OF BOTTOM FRICTION OF SILT BEACH

Wave is one of the important dynamic factors on coastal zone. Since most ports and coastal projects are built in shoaling water, the wave parameters in shoaling water should be given for planning and design work. Generally speaking, from the meteorological elements only the deep water wave parameters can be obtained, and the wave observation stations are often set at different water depths. It is therefore necessary to calculate the wave parameters in shoaling water. In this paper, We deal with the mathematical model for wave deformations in shoaling water, in which both the refraction due to water depth variation and energy dissipation due to bottom friction in the process of the propagation of the wave are taken into consideration and the water oscillation is assumed to be linear simple harmonic wave. In the case of wave traveling over a long distance in shoaling water, the effect of energy dissipation due to bottom friction upon the attenuation of wave height has been taken into account. In this present study, using the wave records measured simultaneously at water depths of-16m and -5m in LIAN-YUN PORT, We have determined the friction coefficient for silt beach. For combination of H～T, the bottom friction coefficient f=0.01 is recommended.