Lateral flushing regime for managing emitter clogging under drip irrigation with saline groundwater

Water scarcity forces saline water to be used in the Bohai Rim Region, China. However, emitter clogging is a persistent and widespread problem in drip irrigation systems when irrigating with saline water. To find a suitable lateral flushing regime for drip irrigation systems using saline groundwater, the objective of this study was to evaluate the effect of five different lateral flushing frequencies. The lateral flushing frequencies were at 1-, 5-, 10-, 30- and 50-day intervals using saline and fresh groundwater. The total duration of irrigation was 100 days, with a total application of 122 h for each water source. The drip irrigation system consisted of hydrocyclone separator, disc filters and screen filters with inline-labyrinth emitters and thin-wall laterals. The results of this experiment are trusted only at such conditions, and show that emitter discharge and uniformity decreased in all treatments. Flushing laterals every 5 days was adequate to control emitter clogging for drip irrigation systems applying the fresh groundwater, while the other three less flushing frequencies failed to prevent clogging. Emitters in the saline groundwater treatments clogged earlier and more severely than those in the fresh groundwater treatments. Five flushing frequencies under drip irrigation using saline groundwater failed to prevent clogging. Based on the findings above, to better control emitter clogging, freshwater is suggested to be used to flush laterals following irrigation with saline groundwater and longer flushing duration is recommended, which needs further study.