Modeling of Water Distribution under Center Pivot Irrigation Technique

Aiming to quantify the impacts of the center pivot irrigation technique on soil moisture dynamics and to improve irrigation crop water needs, a mathematical model was developed to estimate the water distribution pattern of a center pivot. The model is based on the ballistic theory modeling of a single sprinkler radial curve that simulates the trajectories of the droplets discharged by the sprinkler's nozzle. Subsequently, a water distribution pattern of a sprinkler irrigation technique (and ultimately center pivot) can be accurately estimated. This paper describes the theoretical and mathematical approaches of the developed model and its application in the case study, which was Las Tiesas farm in the area of Barrax, Spain, because the model was expanded to take into account the presence of not only one center pivot but multiple ones. In the case study, several center pivots with different characteristics in terms of size and hourly irrigation rates are present. The model correctly estimates the water distribution as it takes into account the different spatial (different sizes of pixels) and temporal basis (hourly and daily basis) and correctly estimates the water distribution when compared with satellite data. The results are given by the model, which is strictly done in the following order: simulating droplets trajectories, water distribution radial curve of single sprinkler, overlapped sprinklers patterns, and center pivots water distribution radial curve and patterns. The mathematical model gives the water distribution pattern under a center pivot irrigation system on a daily and hourly basis. The model can be adjusted to give the results not only for one center pivot but for two or more as desired.