Effect of canopy thickness and canopy saturation on the amount and kinetic energy of throughfall: An experimental approach

To investigate how canopy thickness and canopy saturation affect the amount and kinetic energy of throughfall, we conducted indoor experiments using a 9.8‐m‐tall transplanted Japanese cypress (Chamaecyparis obtusa) and a large‐scale rainfall simulator with spray nozzles at a height of 16 m. The amount of throughfall and raindrop sizes and velocities were measured at twenty‐four points under four canopy structures generated by staged branch pruning. Decreasing the canopy thickness resulted in increases of the initial throughfall amount, volume proportion of large throughfall drops, the number of drops with high velocities, and throughfall kinetic energy. Compared to a saturated canopy, a canopy undergoing wetting had lower throughfall amounts and volume proportion of large drops, but higher mean drop velocity. Canopy thickness affected throughfall generation by affecting the processes of canopy saturation and drop generation within the canopy.