The present invention provides a system and method for maintaining desired pressure levels in an irrigation system when the flow rate available to the irrigation system is reduced below the system's required flow rate. According to a first preferred embodiment, the present invention teaches a method which includes the steps of: receiving and storing irrigation system information including sprinkler specifications, flow rates and pressure requirements； receiving and storing an irrigation plan to be executed including the target amount of an applicant to be applied to a target area； determining an available flow rate to the irrigation system； determining a required flow rate of the irrigation machine； comparing the available flow rate to the required flow rate to determine whether the available flow is sufficient for the system based on the sprinkler specifications； adjusting the pulse rate of the sprinklers to reduce the require flow rate to at least the available flow rate； and calculating and selecting a lower ground speed required to apply the target amount of applicant to the target area based on the selected pulse rate for the sprinklers.
