Computer-controlled variable intensity rain simulator

Natural rainstorms have dynamic intensities; thus, a large portion of total precipitation may be received during a short time. Natural rainstorms also have both variable drop sizes and kinetic energy. Accurate studies of sediment transport and infiltration require realistic duplication of natural rain kinetic energy and intensities. Rain simulator designs must be capable of producing dynamic multiple intensities and corresponding multiple drop sizes to simulate variable kinetic energies. Many simulators are capable of producing rain with multiple and, in some cases, dynamic intensities, but a simulator that can vary both the intensity and kinetic energy is needed. Our objective was to design and build a rain simulator for field use that realistically duplicated natural rain storms. A computer-controlled solenoid-valve multiple nozzle type rain simulator was developed. The computer not only controls solenoid valve activation of the rain simulator during operation but also measures runoff and records rain application and runoff data to a log file for processing. The simulator has control software that controls and monitors all processes. The rain simulator is capable of uniformly applying water (coefficient of uniformity = 84-94%) with a dynamically changing intensity of up to 200 mm h-1 and kinetic energies ranging from 15.0 to 23.5 J m-2 mm-1. Uniformity of application was achieved by oscillating the nozzles in two directions. Field operation of the simulator is enhanced by its portability. The measurement area is easily modified using in-line handrail connectors to change support frame dimensions, thus accommodating infiltration and chemical or sediment transport studies