Application of a network camera system for cusp formation on the Hachigasaki beach, Ishikawa, Japan

摘要

海象特性や漂砂のメカニズム解明には，沿岸波浪や地形変動モニタリングの技術開発が不可欠である．本研究では，鈴木ら(2008)の手法に基づき，ネットワークカメラを活用した画像観測システムを構築し，石川県珠洲市鉢ヶ崎海岸に適用して長期連続観測を行うとともに，現地測量との比較やメガカスプ地形の変動解析を通じてその適用性を検証した．その結果，ネットワークカメラによる汀線位置の定量化手法は十分な精度を有することを確認した．また，メガカスプの発生・消滅と入射波特性との相関解析に本システムを適用し，鉢ヶ崎海岸におけるカスプ地形の発達特性と入射波特性との関係を示した． We have developed a local remote sensing system that allows the quantification of nearshore morphology. In this system a network camera is installed on a high building. The camera is connected to a laptop computer which controls the data acquisition procedure. Image processing such as averaging (time exposure) and rectification are conducted in order to examine the morphological variation. The system has been applied to the field observation of Hachigasaki Beach, Ishikawa, Japan. Continuous observations have been conducted since November 2007. The comparison between image analysis and ordinary field survey shows good accuracy of the measurement. Various morphological features have been captured such as the formation of cuspated features of shoreline. These results show the high capability of the developed system to remotely measure the coastal morphology on sandy beaches.