The wetted area uniformity of the rainfall generated by different sprinkler nozzles

Abstract

Since the 1930s several conceptions of rainfall simulators were developed to perform runoff experiments, soil water infiltration, water erosion, persistence of phytosanitary products, etc. The uniformity of the rainfall generated is a parameter used to validate a rainfall simulator conception design. On this subject, this work aimed at identifying the wetted area uniformity of the rainfall generated by different sprinkler nozzles. The study was divided in two stages: experimental data collection; and, calculation of wetted area uniformity. In the first stage it was used an experimental bench to generate rainfall. The experiment was carried out under completely randomized, factorial 3 x 3 x 3 experimental design, with 27 treatments and six replications (162 experimental units). The treatments were a combination of three sprinkler nozzles (P1, P2 and P3), three sprinkler heights from the ground (1.1 m, 2.1 m and 3.1 m), and three water pressures (50 kPa, 100 kPa and 150 kPa). A mesh of 289 plastic collectors was used for stored the water volume of the rainfall generated from the experimental units. In the second stage, it was calculated the water distribution uniformity using the Christiansen Uniformity Coefficient (CUC) for the areas of 2.56 m², 1.44 m², 0.64 m² and 0.16 m². As a result, the higher the water pressure and sprinkler nozzle height and smaller the land plot, the greater the tendency to get CUC values classified as good or excellent. The sprinkler nozzle P1 showed the best results, so the conclusion is the wetted area uniformity is an important parameter to consider in the selection of sprinkler nozzles in the rainfall simulators design.