Portable rainfall simulator and plot unit for use in field studies of infiltration, runoff and erosion

Equipment is described for determining infiltration, surface runoff, and soil- and nutrienterosion characteristics of field sites. The equipment is robust and portable, and can be rapidly assembled, operated and dismantled by one person. The 10 x 6 ft plots are enclosed by a mild-steel top, jointed side-sections, and an angle-iron collecting drain with an outlet leading to a container of suitable size. Simulated rainfall is supplied to the plot from drums of water by means of a mobile engine-driven centrifugal pump fitted with a by-pass valve. The rain is directed on to the plot with a hand-operated boom and nozzle from which the amount and intensity of the rainfall are controlled. This equipment delivers simulated rain with median drop size of 1.3 mm at an intensity of 320 points h-1and a terminal velocity of 26 ft sec-1. These values are generally similar to those found for comparable natural storms. Some field applications are described.