首页|Spatial and Temporal Variability of Water Application via a Center Pivot
Spatial and Temporal Variability of Water Application via a Center Pivot
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NETL
NSTL
Asce-Amer Soc Civil Engineers
The effect of discrete movement of center-pivot towers on water distribution uniformity is a phenomenon difficult to demonstrate in the field; thus, in this paper, the dependence of uniformity of water application on the movement of the towers was investigated. To accomplish this, global navigation satellite system (GNSS) receivers were installed on three center-pivot towers to track their location during system operation. The data obtained were modeled by a computer program developed in Visual Basic for Applications, in an Excel software spreadsheet. Analysis of the temporal behavior of water depths due to the movement of each tower was described by Fourier series analysis. The results showed that towers closer to the center of irrigated circle presented longer stopping times, shorter movement times, and lower speeds, which together resulted in greater variability in applied water depth. Irrigation uniformity was affected by the misalignment angle between center-pivot spans, with uniformity being greater with smaller misalignment angles. Misalignment angles below 2° are not recommended because they result in very short cycle times (time in motion), which can cause the alignment sensors in the towers closer to the pivot point to fail, and therefore prevent movement. Finally, the amplitude of water depths as a function of tower movement increased when the misalignment angle increased. With the Fourier series analysis, regarding the interval between dominant peaks, it is possible to verify the influence of the equipment stoppage time on the water application cycles of each tower, and consequently on the overall uniformity.
Discrete movementIrrigation performanceSimulation of irrigation uniformity
Fidel Luis Rodrigues Tambo、Luiz Antonio Lima、Michael Silveira Thebaldi、Flavia Vilela Correa
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Faculty of Environmental Engineering and Natural Resources, Dept. of Agricultural and Environmental Engineering, Universi-dade Zambeze, Alfredo Lawley Ave., 1018, Matacuane, Beira, Sofala 2100, Mozambique
Dept. of Water Resources, Universidade Federal Lavras, Campus Universitario, P.O. Box 3037, Lavras, Minas Gerais 37.200-900, Brazil
NETL
NSTL
Asce-Amer Soc Civil Engineers
