LOCALLY CONCENTRATED DAMAGE AT SHIMONIIKAWA COAST, TOYAMA BAY, JAPAN DUE TO GIANT SWELL WAVES

Roshan Suminda Ranasinghe, Yutaro Fukase, Shinji Sato, Yoshimitsu Tajima

Abstract


This paper summarizes results of the preliminary research work, which was completed on identifying and assessing the details of locally concentrated damage along the Shimoniikawa coast, Toyama Bay, Japan due to high swell waves (Yorimawari waves, in Japanese), which occurred on 24th February 2008. A comprehensive analysis has been performed on water surface elevations converted from the total water pressure data, which were obtained at Tanaka observation point from 14th February – 29th February 2008 to investigate the strength of these waves. The spectrum analysis showed a perceptible development of long wave components during this event, which was generated by the nonlinear (secondary) interactions of free waves. Several other mechanisms were also found to be in existence, which were responsible for the high wave overtopping and damage due to concentration of waves at some sites along the Shimoniikawa coast. Furthermore, numerical simulations have been performed to verify the wave transformation and concentration of waves at damaged sites using a model developed based on Nwogu (1993) Boussinesq-type equations.

Keywords


swell waves; spectral density; nonlinear interactions; Boussinesq-type model; wave-current interaction

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