Abstract
An intensive research was conducted in a small headwater basin (0.56 ha) in the Tama Hills to clarify the mechanism of stormflow generation. Field observation was carried out during and after the 130.5-mm rainstorm of Oct. 7-8, 1979.
The relationship between subsurface water behavior and stormflow generation was established at each stage of the rainstorm by using fifty-six observation wells and forty tensiometers. Three contributors to stormflow generation, subsurface stormflow in the A-horizon, saturation overland flow, and flow from the shallow groundwater body, were recognized. A quantitative analysis of the observed results revealed that the subsurface stormflow in the A-horizon was the most important contributor to stormflow generation in the experimental basin. In such a region as Japan, where rainstorms with a total rainfall of more than 100 mm often occur, much more attention should be concentrated on the role of the A-horizon in stormflow generation.
