Distorção da distribuição de água aplicada por sistemas autopropelidos de irrigação em condições de vento

Abstract

Distortion in spatial water distribution by sprinklers due to windy conditions can be modeled by six empirical parameters. These parameters define the drift and range shortening according to Richards & Weatherhead theoretical model (1993). Determination of these parameters is performed through water distribution trials using rainguns mounted on traveling machines. The objective of this study was to develop a computational routine, written in Visual Basic 6, to adjust wind distortion parameters from data obtained by the water distribution trials of traveling machines. A first (Steepest Descent Method) and second (Newton Method) order numerical procedure was used to adjust wind distortion parameters. As input to the computational routine, data were used from water distribution trials held under two different wind conditions, with a PLONA-RL250 sprinkler operating at 392 kPa working pressure, 14 x 5 and 14 x 7 mm nozzle sizes on a traveling machine with a wetted sector angle of 240º and traveling speed of 30 m h-1. In the adjustments of the parameters to the computational routine, 1.521 and 2.307 mean deviation values were found between estimated and observed values of water depths. Based on the estimated parameters, it is possible to simulate spatial distribution of water of the sprinklers for any wind orientation and speed values that do not exceed the ones in which the parameters were determined.