A Laboratory Rainfall Simulator for Infiltration and Soil Detachment Studies

A laboratory rainfall simulator with high intensity precision and nearly uniform rain distribution was developed for studying rain infiltration into soils and soil detachability by rainfall. The rainfall simulator consists of an assembly of closely packed hypodermic syringes with plungers driven by a common plate. Rainfall intensity is determined by controlling the plunger speed at variable motor speeds. Rain is distributed uniformly by superpositioning three independent motions—rotation, and perpendicular and linear motions in the horizontal plane. Rainfall intensities were generally within 2.5% of predicted values. The average coefficient of variation of rain distribution for various rainfall intensities over a 100‐cm2area was reduced from 31.9% with no motion to 8.5% with rotation and linear motions.