An Experimental Span Device to Determine Precipitation Profiles (Water Application Rate) on Center Pivot Irrigation Systems

On center pivot irrigation systems the application rate intensity increases from the pivot point to the moving end. As a result, application rate may exceed the soil's infiltration capacity. The resulting runoff may cause erosion, reduce the uniformity of irrigation and cause losses in water, energy and crop production. Center pivot irrigation designers must provide information for a safe application rate, depending on soil type and conditions, the slope and the weather, avoiding pounding or runoff on the surface. The goal of this experiment was to determine intensity profiles at the distal end of center pivot irrigation systems equipped with D3000 Pivot Sprayhead (R) and N3000 Pivot Nutator (R) and look for the best theoretical adjusted elliptical profile. A stationary lateral was used to reproduce the distal end of center pivot irrigation systems on 20, 30, 50 and 70 ha irrigated areas, on the basis of 1.2 L/(s.ha) system capacity. The practical way to determine sprinkler's profiles and wetted diameters was to place catch gauges in the precipitation area and record results. After plotting the results, elliptical water application-rate profiles were selected to represent the desired precipitation profiles. The results may be used as guidelines for center pivot irrigation system design when equipped with the sprinklers and the conditions used in this experiment.