2022 年 16 巻 4 号 p. 80-86
Previous studies have proven that rainfall–runoff characteristics in headwater catchments are affected by many factors, including topography, geology, and vegetation. However, only a few studies have explained the geological effects on rainfall–runoff characteristics based on observations from various catchments. In this study, we conducted runoff observations in 19 headwater catchments in two forests with different geological characteristics; based on these observations, we further conducted direct runoff and hydrograph recessions analyses. The runoff characteristics of the catchments were significantly affected by their local geological settings. Some catchments did not follow average trends, especially catchments with large baseflows, because of the effects of geological structures, such as dips and strikes in sedimentary-rocks and joints in granite. These catchments were likely to have wetter riparian zones, thereby facilitating direct flow, even in the case of reduced rainfall.
