FIELD SURVEY ON THE ICE JAM THAT OCCURRED IN MARCH 2023 AND ESTIMATION OF ICE BREAK-UP PERIOD

Abstract

 We conducted a field survey of ice jams that occurred in Hokkaido in March 2023, and attempted to obtain quantitative knowledge of the ice jam phenomenon. The scale of ice jam was evaluated based on the amount of water level rise (∆𝐻) when ice jam occurred. By comparing the past occurrences with those in March 2023 using ∆𝐻, it was found that the water level change ranged from 0.57 m to 4.22 m. There is a positive correlation (r=0.70) between cumulative rainfall before ice jams and ∆𝐻. We tried to apply the method of estimating the time of ice break-up. It was confirmed that the ice thickness variation acceleration 𝑃𝐵 appears before the ice jam occurrence time, and that the time of ice break-up can be estimated.