Raindrop production for laboratory watershed experimentation

A technically efficient method for producing artificial raindrops is presented. This approach is based upon broad basic requirements to be adopted in the systems engineering for an experimental investigation on watershed hydraulics. Modular construction of the raindrop-producing device is adopted, allowing variable time distribution and areal coverage of rainfall intensities from 0.75 to 13 in./hr. Theoretical and photographic comparisons are made for the formation and velocity determination of 0.126-in. (3.2-mm) drops produced through polyethylene tubes of 0.023 in. ID. Procedures and formulas are given for making such determinations under other conditions. The proposed rainfall producer provides fast response to on-off commands and produces in the laboratory controllable simulated storms of flexible time and areal distribution patterns.