Yukiko MATSUNAGA
Predistion of Wave Conditions for Nesting in Mid-Niigata Coastal Area
Tokuzo HOSOYAMADA
In the Sea of Japan coast including Niigata coast, by the strong winds such as typhoon in summer and monsoon in winter, which causes high waves. Due to high waves, it occurs that ships can't sail, the land is encroached and roads and houses are flooded and damaged by overtopping waves. When provisions for these businesses, it is important to analyze wave conditions of this area. But, in Niigata Prefecture, observations of wave conditions can get only two points of Naoetsu and Niigata. In case of other areas in Niigata Prefecture, there is a need to obtain wave conditions anew with observation or prediction by computational model.
this study, by using the third generation wave spectrum models SWAN nested run of 3 phases, which was computed to predict the wave conditions in mid-Niigata coastal area. And the prediction accuracy is improved by nesting. The computational periods are March, August,November and December,2008.
First, it was confirmed that the computed results are predicted correctly by comparing observations of NOWPHAS at Naoetu. In the wave height and the wave direction, results are good accuracy. And by nested run the prediction accuracy is somewhat improved. Also, the conditions of sea wind in mid-Niigata was obtained by objective analysis data used for wind input data. In the area, the wind direction from WSW, W and WNW are high frequency. In particular, the wind velocity is especially strong in December.
Next, in Izumozaki,the wave direction from WNW and NW has been dominated. It was because Izumozaki are located in between the Sado Isle and the Noto Peninsula. By shielding effects of these, waves are incident from between these. In case of the direction of WNW, the wave heights are higher on the side of northwest edge of the Sado Isle in Sea of Japan. But in the mid-Niigata coastal area, affected by the Noto Peninsula and the Sado Isle, the wave heights are smaller. However, because the shielding effect is small compared with other coastal areas, so the wave height is higher.
Thus, the SWAN nested run can be predicted accurately. And the wave conditions in mid-Niigata coastal area can be analyzed by comparing to other areas
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