Partitioning of splash and storage during raindrop impacts on banana leaves

Abstract

The rainfall interception processes that affect water distribution into storage, splash and dripping from foliage were investigated for banana leaves with different inclinations, in relation to incident rain drop diameter, kinetic energy and fall height. Drops of 2.3, 3.5 and 6.0 mm were released from various heights onto leaf samples of different ages and flexibility, with adjustable inclinations. Water volumes stored on the samples and those splashed, dripped and evaporated from the samples were measured. Splash occurrence depended on fall height according to the Weber number. It always occurred for 2.3-mm drops striking the target at 92.6% of their terminal velocity, and for release heights greater than 0.14 m for 6.0 mm gravity drops. Splash and storage depended on drop diameter and decreased as leaf inclination increased from 0° to 17° then remained stable beyond that. Splash and drop kinetic energy were strongly linked since the proportion of splash increased with drop kinetic energy which conversely had a limited effect on storage. For leaf inclinations from 27° to 47°, splash of 6.0-mm drops increased up to 40% in comparison with splash measured for leaf inclination of 17°, inducing water sweeping away from the sample surface as non-vertical dripping. In our range of conditions, leaf age and flexibility had no significant effect on storage and splash. Finally, these results allowed us to develop the empirical relationships needed for application of a rainfall interception model to banana plants in order to simulate water flows under the plants to manage erosion, agrochemical leaching and disease propagation hazards.