Author(s): Yutaro Hashimoto; Keisuke Yoshida; Md. Touhidul Islam
Linked Author(s): Keisuke Yoshida
Keywords: Diversion weir vegetation sandbank diversion flow rate Dupuit-Forchheimer law
Abstract: Effective river management requires a thorough understanding of how vegetation dynamics influence flood flow characteristics. This study explores the impact of vegetation on diversion flow rates in the Asahi RiverHyakken River system in Japan, using three-dimensional (3D) numerical simulations with the DupuitForchheimer law. We modeled flow resistance under two conditions: a planned flow rate of 6,000 m3/s and a historical maximum of 4,251 m3/s. The simulations incorporated various vegetation scenarios, including the 3D distribution derived from 2017 Airborne Laser Bathymetry (ALB) measurements, complete sandbank vegetation removal, and full bamboo replacement. Our results reveal that vegetation type plays a crucial role in flow resistance and distribution. Tree vegetation, with its high washout potential, reduces resistance and redistributes flow, while bamboo remains structurally stable, especially during high-flow events. These findings emphasize the need for adaptive river management strategies that account for the distinct mechanical responses of different vegetation types, such as the susceptibility of trees to lodging and the resilience of bamboo.
Year: 2025