LONG-TERM VARIATION OF WAVE CHARACTERISTICS ON THE KAETSU COAST, JAPAN

抄録

 Kaetsu Coast is located on the middle north coast of Japan. This area has been suffering from various problems, including the progress of severe coastal erosion, frequent occurrence of rip current accidents, reduction of coastal habitats, and others. In order to cope with these problems, physical understanding of long-term wave characteristics is essentially important as basic engineering information. Accordingly, this study examines the long-term wave data observed at the Kanazawa Port in duration 1971-2012 in order to clarify the long-term as well as the seasonal characteristics in significant wave properties. On the overall, the seasonal variation in wave height, period, and direction is shown to be significant. The monthly-mean wave height and period are correlated with 2nd order polynomials very well. For the long-term variation, the annually-mean significant wave height indicates no significant trend. On the contrary, the Lepage statistical test detected an abrupt increase in the annually-mean significant wave period around 1990. In relation to these changes, the long-term variation in monthly-mean wave characteristics shows that the wave slope becomes smaller in the last two decades. The Mann-Kendall statistical tests demonstrated that the monthly-mean wave height and period in July have significantly increased during the study period. Several attempts have been made to correlate these features with climate changes.