A comparison of two variable intensity rainfall simulators for runoff studies

Two different rainfall simulator designs were developed in order to obtain variable rainfall intensities with drop sizes and energies similar to natural rain. One of the rainfall simulators was constructed using a full-cone jet nozzle and achieved variable rainfall intensities by means of a solenoid valve (RS1). The second one (RS2) used three plane-jet nozzles to obtain variable rainfall intensities by varying the number of nozzles working simultaneously. Both rainfall simulators provided realistic rainfall intensities (between 20 and 80 mm h−1), drop sizes, and kinetic energies for runoff experiments, with uniformities ranging from 80 to 92%. The design using plane jets (RS2) provided a more realistic drop-size distribution for Mediterranean regions and lower cost (solenoid valve and power supply were not necessary) than that using solenoid valve (RS1).