Abstract
The perturbation in hydraulic networks for irrigation systems is often created when sudden changes in flow rates occur in the pipes. This is essentially due to the manipulation of hydrants and depends mainly on the gate closure time. Such a perturbation may lead to a significant pressure variation that may cause a pipe breakage. In a recent study, computer code simulating unsteady flow in pressurized irrigation systems—generated by the farmers’ behavior—was developed and the obtained results led to the introduction of an indicator called the relative pressure variation (RPV) to evaluate the pressure variation occurring into the system, with respect to the steady-state pressure. In the present study, two indicators have been set up: The hydrant risk indicator (HRI), defined as the ratio between the participation of the hydrant in the riskiest configurations and its total number of participations; and the relative pressure exceedance (RPE), which provides the variation of the unsteady state pressure with respect to the nominal pressure. The two indicators could help managers better understand the network behavior with respect to the perturbation by defining the riskiest hydrants and the potentially affected pipes. The present study was applied to an on-demand pressurized irrigation system in Southern Italy.
Highlights
Pressurized irrigation systems have been developed during the last decades with considerable advantages as compared to open canals
The strong variation of the discharges flowing into the network due to the variation in the demand is the first provoker of perturbation in pressurized irrigation systems
The strong variation of the discharges flowing into the network due to the variation in the of 14 first provoker of perturbation in pressurized irrigation systems
Summary
Pressurized irrigation systems have been developed during the last decades with considerable advantages as compared to open canals. They guarantee better services to the users and a higher distribution efficiency [1]. On-demand systems are designed to deliver water at the flow rates and pressures required by on-farm irrigation systems, considering the time, duration, and frequency as defined by the farmers [2]. In pressurized systems operating on-demand, a group of hydrants operating at the same time is known as a configuration. Changing from a configuration to another is the main origin of perturbation in pressurized irrigation systems [3]. Many authors [4,5] have emphasized that improving the performance of existing irrigation schemes is a critical topic to decrease excessive water use and enhance system efficiency
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