Abstract
The majority of water catchments in Japan are located in mountainous areas that can produce large quantities of runoff, which may lead to flooding, erosion, and landslides. Thus, it is important to know the minimum total rainfall required to generate surface runoff by estimating the water storage capacity of each catchment. The threshold of minimum total rainfall required to generate surface runoff occurs when at least 95% of total rainfall becomes total loss rainfall such as infiltrates into the ground. The variation in this value is dependent on the catchment characteristics. Based on the relationship between total rainfall and total loss rainfall, the average values of minimum total rainfall required to generate surface runoff and total loss of saturated rainfall were 51.3 mm and 108.5 mm, respectively. Catchments consisting of a smaller area of sedimentary rock and higher values of drainage density, elongation ratio, and catchment width tended to have smaller values of minimum total rainfall required to generate surface runoff.
