SIRIAS: a simulation model for sprinkler irrigationII. Calibration and validation of the model

The SIRIAS model has been developed to simulate water distribution of a sprinkler pattern distorted by wind, thereby eliminating the necessity of carrying out laborious in-field tests to determine water distribution in a irrigation system. The model is based on the application of a ballistic theory to drop movement distorted by wind. The necessary data correspond basically to the radial distribution test of the sprinkler. The model has been calibrated and validated using field tests for the different combinations of sprinkler–nozzle–height. The following internal performance parameters of the simulation model SIRIAS are considered as optimal: number of throw directions (180), drop diameter increment (0.05 mm), number of iterations per second (50). The corrector coefficients that best fit the simulated and in-field measured water distribution pattern at 350 kPa for block irrigation tests were: K1=1.85 and K2=0.15. The mean absolute error in block irrigation CU values was 2.7%.