Dynamic Model for Water Distribution Pattern of Center Pivot Irrigation System

In order to evaluate performance of the center pivot irrigation systems, an understanding of water application characteristics of these systems is necessary. A new model and its computer program are developed to calculate applied water depth and coefficient of application uniformity of center pivot systems. The model uses water distribution pattern of stationary single spray nozzle as an input and simulates center pivot overall water distribution pattern. For this purpose, two static and dynamic square grids are considered. The static grid is obtained by dividing irrigated field to square components. The dynamic grid is resulted from adapting a grid with square components on water distribution pattern of single spray nozzle and is moved with moving spray nozzle on the center pivot lateral. Dynamic grid is moved over static grid. Water depths received in the field are determined in static grid components via considering water applications rates in dynamic components. Distribution patterns are overlapped in areas covered by adjacent spray nozzles. The model outputs are water depths received in the field in all components of the static grid and water application uniformity coefficient. In order to evaluate and validate the model performance, several experiments were conducted in the field and the model was run for the same conditions. The results showed high accuracy of the model in simulating water distribution patterns of the center pivot irrigation systems.