For comprehensive management for marine debris, a key issue is to develop a numerical tool for generation, movement and deposition of floating litter in rivers, one of main sources of marine debris.In this study, we evaluated fracture conditions of herb in a river under flood conditions. For this purpose, we conducted field measurements for the amounts of herbs before and after the floods, and ADCP measurements in the Edogawa River. The measured results indicated that herb-fracture conditions under various fluid forces were evaluated for leaves and stalks, separately. A 2D river-flow simulation was performed to evaluate the outflow of herbs in the field site using the above modeling of herb-fracture conditions.
