2025 Volume 77 Issue 5 Pages 3-10
In this study, we collected literature on driftwood disaster cases over the past 40 years, organized basic data on watershed area, rainfall, and the volume of driftwood generated and transported to examine changing trends. Furthermore, the relationship between the volume of driftwood generated and transported, the volume of sediment production, and the peak flood discharge was clarified. As a result, the median watershed area where driftwood disasters occurred was 0.6 km2 between 1980 and 2000, and 1.7 km2 after 2000. Recently, driftwood has occurred even in large watersheds, and the volume of driftwood itself has been large. Additionally, the upper limit line of the volume of driftwood generated and transported per unit area was generally increasing.
