2024 Volume 80 Issue 27 Article ID: 24-27030
In this study, we analyzed the frequency of heavy rainfall events and meteorological factors in the Ishikari River basin over the past several decades. Observations indicate that the frequency of heavy rainfall events has increased since the late 1990s, especially the number of events caused by stagnant fronts has doubled. The 1981 flood, the largest ever recorded in the basin with average daily precipitation exceeding 100 mm/day, is known for being caused by a front and a distant typhoon that brought heavy rainfall over a two-day period. Furthermore, using historical experiments of ensemble climate prediction information, it was found that the probability of a heavy rainfall event exceeding the historical maximum was more than twice that of a heavy rainfall event caused by a frontal pattern than by a combination of a frontal pattern and remote typhoon.
