The hypothesis of a linear relationship between wetted area of a sprinkler and the wind velocity which is assumed by the Richards & Weatherhead semi empirical model for simulation of wind effects on gun type water application distribution was evaluated. Distances from the Plona-RL250 gun type sprinkler to the upwind, crosswind and downwind edges was determined in 53 field testes, held under different wind conditions and were used to evaluate the suitability of the proposed linear relationship. A linear least square fit for each set of data indicates that, for each 1 m s-1 increase in wind velocity, there is: (i) a 6.3% decrease on the distance to the upwind edge (R² = 0.737); (ii) a 7.3% decrease on the distance to the crosswind edge (R² = 0.850); and (iii) a 1.3% increase on downwind edge distance in relation to the no-wind radius of throw. These results indicate that, for the range of wind velocities considered in this study (from 0 up to 5 m s-1) the linear relationship between sprinkler reach and wind velocity can be accepted.
irrigation; semi empirical model; simulation
