A modified portable rainfall simulator for soil erosion assessment under different rainfall patterns

Rainfall simulators are devices used in studies on erosion and water infiltration in soil and have different classifications and operating characteristics. Most of these devices simulate rainfall with constant precipitation intensity (PI), which does not represent the characteristics of natural rainfalls and may lead to significant differences in studies on soil and water losses. Here we have developed an automatic PI control system for a rotating simulator equipped with nozzles, through the regulation of the shutter disc rotation, to simulate different rainfall patterns. We have set up an electronic control system that acts on the motor power frequency inverter, allowing the user to enter the desired rainfall pattern through a text file, recorded on a micro SD memory card. For evaluation purposes, different rainfall patterns were programmed for 40 min duration, with maximum PI peaks of 110 mm h(-1) and total depth of 30 mm. The new panel of the modified simulator, built with user-friendly interface, enables the selection of the desired rainfall pattern and the operating mode (manual or automatic). The rainfalls were adequately simulated and, even with variation in PI, the modified simulator showed application uniformity above 75%.