Yuki Onda

Grasping wave characteristics during high waves on the Kashiwazaki central coast

INaoyuki nukai

Just after 2:00 pm on August 16, 2022, an accident occurred in which a grandfather who was visiting with a third-grade elementary school boy drowned on the Kashiwazaki Central Coast in Higashiminato-cho, Kashiwazaki City. Typical beaches, such as coast, have relatively gentle slopes, and because breaking waves offshore far from the shoreline, the wave energy reaches the land in an attenuated state. However, on the Kashiwazaki central coast where the accident occurred, wave conditions in the sea area in front of the coast do not attenuate when the wave direction is not affected by the breakwater. Therefore, it can be seen that the Kashiwazaki central coast is a coast where waves that do not break collide with the shoreline and travel up the coast with the same force. Therefore, there is a risk of accidents not only in the water in front of the coast, but also on the sandy beach.
The purpose of this research is the characteristics of currents in front of the coast, and to obtain knowledge for preventing future accidents.
Calculations are performed using CADMAS-SURF 2D to understand the characteristics of the flow in front of the coast. For this purpose, we need topographical data of the Kashiwazaki central coast and wave data at the time of the accident. Therefore, we will grasp the topographical data of the Kashiwazaki central coast through field surveys. Next, we will confirm the waves in Kashiwazaki at the time of the accident. However, waves at Kashiwazaki at the time of the accident are missing, so waves at Naoetsu are used to estimate waves at Kashiwazaki. Using the obtained Kashiwazaki's waves, we will understand the behavior of waves flowing down and up the sandy beach. As a result, it is thought that there is a high possibility that an accident will occur due to waves running up on the Kashiwazaki Central Coast not only underwater but also on the sandy beach.