Development and validation of a modified model to simulate the sprinkler water distribution

Water distribution uniformity is important for the design of a sprinkler irrigation system. The movement of enormous water droplets after leaving the sprinkler nozzle significantly affect the water distribution of an individual sprinkler. Based on modified mathematical models of droplet dynamics and evaporation, a method for simulating droplet motion was proposed, and a corresponding software was developed as well. Using the given radial water distribution data of an individual sprinkler, the software can predict the water distribution of an individual sprinkler or a solid-set sprinkler irrigation system under different sprinkler spacing combinations and various environmental parameters. The corresponding combined application rate (P¯), coefficient of uniformity (CU) and evaporation loss rate of an irrigation system could be calculated. The model was validated by indoor and field experiments. The side length of the grid elements constituting the square region was recommended as 0.5 m and the number of spray directions was 180 in the simulation. The results of model validation showed that the simulated radial water distribution of an individual sprinkler agreed well with the measured values, with a confidence coefficient of 0.899. The average relative errors in P¯ and CU between the measured and simulated values were 3.46% and 2.46%, respectively. The developed software package was capable of predicting the water distribution of sprinkler irrigation systems with relatively high accuracy under the conditions investigated.