Drop size distribution and kinetic energy load of rainstorms in Hong Kong

Data on drop size distribution and kinetic energy load of rainstorms are ba sic for rainfall erosivity indices. A simple and relatively inexpensive ins trument was used to asses the instantaneous intensity and kinetic energy lo ad of rainstorms in Hong Kong. Both the drop size and the instantaneous kin etic energy load of rainfall in Hong Kong are greater than in temperate and subtropical climates. The high kinetic energy results from the large size and greater number of raindrops falling per unit time. A high correlation b etween the kinetic energy of rainfall and the amount of rainfall allows for a convenient estimate of the energy load of storms from the amount of rain fall. Of more significance to the erosion process is the determination that about 74% of the total annual rainfall is erosive, containing about three- quarters of the total annual energy load of the rains. The variability of r ainfall parameters within a rainfall and from storm to storm is shown. The energy-intensity relationship, seasonal and annual distributions of rainfal l erosivity are presented. Copyright (C) 2000 John Wiley & Sons, Ltd.