PROGRESS OF EROSION AND WAVES NEAR THE COASTAL EMBANKMENT DURING TYPHOON HAGIBIS ON THE SURUGA COAST

Abstract

 Waves from Typhoon Hagibis were observed by observation equipment installed near the embankment of the Suruga Coast. Five ultrasonic wave gages, three capacitance wave gages, and a far-infrared camera were used for continuous observation at 0.3-second intervals.

 As a result of Typhoon Hagibis, sixty waves reached the vicinity of the embankment during the observation period, and these waves caused vertical beach erosion of about 20-50 cm. The erosion process was classified into four stages according to the erosion speed. From the images taken by the far-infrared camera, the average flow velocity during uprush and down-rush of the measured section was determined and compared with the amount of drift sand, which was found to be correlated with the cube of the flow velocity during the rapid erosion stage.