Designing and manufacturing a portable rainfall simulator

Rain simulation is a method widely used in detecting hydrological and erosional processes. Most portable samples are inconvenient and challenging to transport, have high water consumption and energy demand. The objective of this study was to design and test a rainfall simulator characterized by the following innovative features: 1) Easily transported and assembled in the field, thereby allowing the necessary experimental replicates, and 2) Applicability on different slopes. The first calibration step was related to the spatial distribution of rainfall, the stability of the rainfall intensity, and the reproducibility of the rainfall intensities over time (among successive experiments). Next, the drop size distribution (DSD) and the related rainfall characteristics (median volumetric drop diameter D50 and mean kinetic energy per unit area and unit depth) were evaluated by the flour pellet method. A fluorescent tracer method was used to measure the velocity of falling drops. According to the findings, the Christiansen uniformity coefficient (Cu) of the developed rainfall simulator varies from 77-87% for rainfall intensities of 35-75 mmh-1 . The best rainfall distribution was achieved for rainfall intensities of 55 and 75 mmh-1 , with rain droplet sizes ranging from 0.6 to 3.8 mm. The raindrop velocity was also measured by photo-shooting and revealed a velocity rate of 2.7-5.7 ms-1 . The system allows rainfall simulation on the fields and under laboratory conditions. Moreover, using the simulator, erosion, runoff, and sediment production under natural and intact soil conditions can also be examined with the highest possible accuracy.