Abstract
Forest influences the dynamics of water, sediment, and materials both globally and locally since the forest canopy intercepts precipitation and changes water volume and quality reaching soil surface. The author has measured raindrops and throughfall drops to estimate erosivity in the forest, however, it is found that drop data is useful tool for physical clarification of precipitation partitioning process by trees. The method was developed to partition whole throughfall into free throughfall, splash throughfall, and canopy drip using raindrop data both open and throughfall. Foliage height to generate canopy drips can be estimated by their fall velocities. The theory on the interface between solid (a plant surface) and liquid (a water drop) could explain the difference of canopy drip generation processes among different canopy species and between leafy and woody surfaces, as well as throughfall generation process in different canopy layer structures. This paper illustrates not only the fun, but the usefulness, importance, and future prospects on the raindrop studies.