Abstract
The previous measurements of throughfall and stemflow have been used to provide a quantitative estimate of rainfall interception in the Kiryu Experimental Catchment (34°58'N, 136°00'E). This catchment is situated in a mixed-stand of Akamatsu, Japanese red pine (Pinus densiftora SIEB. et ZUCC.) and Hinoki, Japanese cypress (Chamaecyparis obtusa SIEB. et ZUCC.). Rainfall interception has two components; one is the attached and stored water on the canopy, evaporating after the rain, and the other is the evaporating water during the raining period. The maximum amount of attached water on the canopy has been estimated as an average of 1.92mm in this catchment. This value agrees with the amount of attached water on leaves calculated from the standing crop and the storage capacity of each leaf. The estimated average evaporation rate during the raining period is 0.1618mm/hr. A predictive model of rainfall interception in forest canopies is shown. The amount of attached water and the evaporation rate during raining period has been used in this model. Annual rainfall interception has been calculated with this model for the six years from 1972 to 1977. The annual interception was 290_??_390mm (18.5_??_22.9 percent of the annual precipitation). Annual interception is decreasing, but its ratio to precipitation is increasing as the annual precipitation is decreasing.
