Author(s): Yuki Kajikawa; Yuriko Kameda; Ryuta Ibaraki; Masamitsu Kuroiwa

Linked Author(s): Yuki Kajikawa

Keywords: River confluence; River bend; Flood flow; Three-dimensional flow; Numerical analysis

Abstract: Sedimentation is a problem at the confluence of the Sendaigawa River and the Hattōgawa River, which flow through the eastern part of Tottori Prefecture in Japan, and it is necessary to understand the flow during floods to develop countermeasures. Generally, a depth-averaged two-dimensional (2-D) model is used in numerical analysis of a real river for practicality. However, it is known that three-dimensional (3-D) flows occur at river confluences, thus a 3-D analysis is desirable. In this study, flood flow analysis using a 3-D model was conducted to elucidate the flow regime in the confluence area, and a comparison was made with a 2-D model. A comparison of the depth-averaged velocities between the 3-D and 2-D models showed that the 3-D model reproduced the velocities along the low-water channel stronger. Moreover, the results of the 3-D analysis showed that the flow directions at the water surface and the near-bed of the bend after the confluence were significantly different. In particular, the near-bed flow from the Hattōgawa River was concentrated on the inner bank of the bend.

DOI: https://doi.org/10.3850/978-90-833476-1-5_iahr40wc-p0117-cd

Year: 2023