Departmental Bulletin Paper Seasonal Variability of Wave Characteristics and Related MOrphological Indices on the Kaetsu Coast,Ishikawa,Japan

Nguyen, Trinh Chung  ,  Yuhi, Masatoshi  ,  Ueno, Takuya

48pp.17 - 28 , 2017-03-28 , 金沢大学環日本海域環境研究センター = Institute of Nature and Environmental Technology Kanazawa University
This study investigates the seasonal variability of wave characteristics and related morphological indices on the Kaetsu Coast in Ishikawa, Japan based on long-term wave data observed at Kanazawa Port from I 971 to 2012. First, the seasonal variations of wave energy flux are investigated in combination with the directional distribution. Most of the incoming wave energy is concentrated in the winter season, in which high waves from the WNW, NW, and NNW direction frequently impact the coastline. Second, the characteristics of wave breaking in the near shore area, and breaker height and depth, are examined. Re­lated morphological indices such as the closure depth and the Sunamura index are also estimated. The seasonal variations of these properties indicate common patterns, in which the values are highest in winter, medium in spring and autumn, and lowest in summer. The cumulative probability of breaker depths varies significantly from season to season. The estimated closure depth also indicates distinct seasonal changes. These results indicate that the cross-shore width of significant morphological change is substantially var­iable according to the time. The estimations of the Sunamura indices suggest that the shoreline is advanced during the summer, while shoreline recessions generally occur in other seasons. The transitions from shoreline recessions to shoreline advances are deduced to occur in March. and from advances to reces­sions in September. Third, an analysis ofinfragravity waves is conducted. The patterns of the daily as well as monthly variations of infragravity wave heights are similar to that of wind waves. A strong linear cor­relation exists between the heights of infragravity waves and wind waves.

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