Shigeo KINOSHITA

Basic Research on Accident of Coast in Niigata Prefecture

Tokuzo HOSOYAMADA

The beach accident while bathing in the sea happens frequently every year. In the accident of a shallow sea area, there is a rip- current. A very fast flow has been generated in the sands coast. Recently, there is a rip- current generated because the coast structure increases. In this research, the rip- current in the vicinity of the coast structure of Niigata Prefecture was clarified.
Then, the accident in a past beach was investigated. As a result, the accident occurred by the whole area of the coast. The wind at the accident was featureless. Waves are chiefly incidence from the north-northwest. Then, it observed it in the locale at those conditions. In the observation, two rip- currents were able to be discovered. One is a circulating flow. The maximum flow velocity was 0.67m/s.Another is a rip- current that goes straight from the coast. The maximum flow velocity was 1.58m/s.These had been generated at the similar weather and the walrus condition.
In this research, it has been understood the rip- current is generated in the Niigata Prefecture coast. Moreover, those scales became clear.