EFFECTS OF WIND-WAVES ON SHORT-TERM VARIATION IN DISSOLVED OXYGEN CONCENTRATION IN COASTAL AREA OF OSAKA BAY

Abstract

 Hypoxic water masses have often been observed in the coastal area at the head of Osaka Bay and many studies have been conducted on its behavior. However, the relationship between wave conditions and hypoxia has not been clarified. In this study, the analysis of field observation data of water quality and wave conditions at Kobe Port was carried out. The results showed that there is relationships between wave height and variation in dissolved oxygen (DO) concentration. Numerical simulations were conducted using the three-dimensional flow-water quality-wave coupled model. In this model, the length scale of the surface-injected turbulence is related to the significant wave height and imposed as a surface boundary condition for turbulent mixing length. The model successfully reproduced the DO concentration and the numerical results suggested that wind-waves contribute to improve hypoxia through enhancing vertical mixing of seawater.