Yamasita Akifumi

Study on grasp of flow condition of the rip current to occur in sandy beach Coast
Hosoyamada Tokuzou

The rip current accident occurs every year, but the identification of the scene is difficult. Some observation data of the rip current are accumulated by the field work of the study of the past, but it is individual surges, rip current under the topography condition.Because it was difficult to confirm the rip current visually, speed of the rip current, an outbreak interval depended on what kind of factor or grasped it and examined the grasp technique of flow condition of the rip current in the sandy beach coast.I define the local flow to flow out to the offing as rip current from the neighborhood of shore, and, in this study, observation analyzes it.I perform a field work and observe behavior of the real rip current.I carried out the field work at the Ajirohama shore of Niigata on December 9, 2015.I spray sea surface coloring agent on the local shore at the time of an investigation and visualize rip current. I shoot the state that sea surface coloring agent scatters from the air in UAV. I grasped behavior of the rip current from a picture.I compared the observation level with the estimation level and was able to calculate an equal value.In the shore where topography data are known, it is possible for estimation in rip current speed from a surge condition to some extent if I use a calculating formula of the rip current speed that I used in this study.