Calculation of sprinkler droplet-size spectrum from water distribution radial curve

Obtaining droplet-size spectrum data for agricultural sprinklers is important for predicting wind drift, evaporation losses and droplet effects on the soil. The collection of this data using the pellet method is time consuming, and the more modern optical methods are expensive. Here, an indirect method based on a mathematical approach is proposed, combining the results of a ballistic-analytical model with water distribution radial curve data. The final results of the model were compared to experimental data for droplet-size spectra available in the literature and showed a better agreement than the results of another indirect method based on a ballistic model using a Runge-Kutta numerical solution. This indirect method can be used in models for the design of sprinkler irrigation systems, useful to obtain a good uniformity of water distribution to optimize water use.