Author(s): Honoka Okuyama; Yasuhiro Yoshikawa; Hiroshi Yokoyama
Linked Author(s): Hiroshi Yokoyama
Keywords: River Ice; River Ice Breakup and Jamming
Abstract: In Japan and other countries where the temperature drops below zero, rivers freeze in winter. In early spring, when the temperature rises, river ice breaks and flows downstream. Ice jam occurs when river ice flows and accumulates in the river channel. It causes the water level to rise and leads to various disasters. It is necessary to understand the river ice flow phenomenon, but field observations have not been sufficiently performed. This study successfully performed field observations of the river ice flow phenomenon. We analyzed the field observations and investigated the ice jam locations using Sij (ice jam scale). In any river, Sij can find places where ice jams occur at high risk using less information and is a simple formula basis that enables calculation. River engineers can use it at work, and its adaption in an actual river field is being considered. This study aims to clarify the ice jam that occurred in Abashiri River in Japan in March 2020. Field observations enabled us to understand the phenomena of ice jam initiation, breakage, and re-flow caused by rainfall and melting snow. Surveillance camera images showed that the maximum velocity of the river ice flow was 2.7 m/s at the time of the ice jam and 3.5 m/s at the time of the ice breakup. We found that an ice jam tends to occur in the meandering area. We were able to identify the danger points of the ice jam using the ice jam scale in comparison with the field observation results.
Year: 2022