[M-IS09] Ocean Plastics, an earth science perspective

[MIS09-07] An experiment in predicting beach litter abundance using a particle tracking model with consideration of the effect of leeway drift

*Fukushige Hiroki¹, Shinichiro Kako^1,2, Tetsuya Taneda¹, Akira Tsujimoto³, Atsuhiko Isobe⁴ (1.Kagoshima University , 2.Japan Agency for Marine-Earth Science and Technology, 3.Shimane University, 4.Research Institute for Applied Mechanics, Kyushu University)

Keywords:Beach litter, Beach litter prediction experiment, Particle tracking experience, Leeway drift, Webcam, In-situ beach observation

Hindcasting/forecasting the abundance of beach litter and its variability is very important for efficient and effective countermeasures against marine litter. Therefore, this study conducted a beach litter forecasting experiment in the East Asian marginal seas in conjunction with regional ocean circulation model and particle tracking experiments. To verify and improve the accuracy of the model, a webcam has been installed on the beach at Mitsu-cho, Izumo City, Shimane Prefecture, and the webcam monitors the beach images sequentially every one hour. However, the model used in this study does not implement optimal leeway drift for litter washed ashore on the Mitsu beach. Therefore, in this study, particle tracking experiments were conducted with various types of leeway drift and compared it with the actual amount of litter washed ashore on the beach. The accuracy of the model was verified using the results of in-situ surveys on the Mitsu beach and the beach images taken by webcam. The results showed that the model was able to reproduce seasonal variations in litter and rapid increases of litter abundance. However, it was found that the proportion of countries of origin of the litter differed from that observed on the beach. Possible causes of these factors will be discussed in detail during the presentation.