In recent decades, on-demand irrigation systems have been promoted to increase water useIn recent decades, on-demand irrigation systems have been considered to increase water use efficiency. In this study, the assessment of two traditional rotational pressurized irrigation systems in the Foggia Province (Italy) was carried out. Irrigation system A has an area of 564 ha with 319 pipelines and 251 hydrants and irrigation system B has an area of 445 ha with 280 pipelines and 214 hydrants. The nominal discharge of each hydrant is 10 l/s. In each of the irrigation systems, using the COPAM model 1000 different operation scenarios were investigated. To evaluate the performance of the systems Relative Pressure Deficit (RPD) and Reliability (RI) indices were used. Results showed that the systems are quite flexible and allow to increase the required discharge up to 1.6 times the discharge of the peak period, if needed. With such increased discharges, it is impossible to guarantee the RPD ( ) and RI (RI= 1) indices in 47% of irrigation system A hydrants and 36.9% of irrigation system B hydrants. An updated methodology for optimizing the pipe diameters starting from the current situation was also implemented. Around 23% of pipelines in each system were changed with such methodology. After the new optimization, the number of unsatisfied hydrants in both systems decreased by 94.1% (from 118 to 7 hydrants) and 82.3% (from 79 to 14 hydrants), respectively. Therefore, with such methodology, the irrigation system performance can be improved.
