MEASUREMENT OF SWIMMING ABILITY IN RIP CURRENT AND MODIFY ESTIMATE EQUATIONS OF RIP CURRENT

Abstract

 One of the causes of water accidents that occur near the coast is the rip current. The rip current has the relationship with the wave height, and the current velocity of the rip current occurres corresponds to the wave height. Videlicet, even though when the low height wave occurs, a corresponded low speed current of the rip current occurres in the area, and the water accident caused by this low speed current sometimes occurred. When we play in the water at the coastal area, we move by some moving method, for example, we move by walking in the shallower than a waist depth water area, however, we move by swimming in a deeper than the tip of the foot depth water area. In the other, we move by only hand rowing at the toes barely reached the bottom area. The each moving speed is different, and the rip current speed that each method can be handled is different. Therefore, we measured the moving speed of each method, and grasped the rip current speed that each method can be handled. Secondary, we tried to modify the calculation method about the velocity of the rip current. In this case, only the wave conditions and the depth information are needed. Before modifing the new method, we conducted the some field survey. When we conducted the field survey, the rip current was pigmented by the sea water colorant, and the pigmented current was recorded as the aerial photography by UAV.