A Prediction Model of Labyrinth Emitter Service Duration (ESD) under Low-Quality (Sand-Laden Water) Irrigation

The reasonable evaluation of emitter service duration and appropriate emitter selection have become an important way to improve the efficiency of drip irrigation systems, and also provide a basis for the wide application of drip irrigation technology in agricultural and landscape irrigation. During field irrigation, both irrigation uniformity (CU) and relative average flow (Dra) play crucial roles in crop growth, so it is not appropriate to evaluate emitters based on one of these factors alone. In this study, a new comprehensive index for measuring the operating life of emitters-the emitter service duration (ESD) was established for selecting emitter products in the field. The indoor drip irrigation experiment was carried out under nine kinds of sand-laden water, and the emitters' service duration, based on irrigation uniformity and emitter flow, was tested. By analyzing the individual effects and the comprehensive effects of them, the comprehensive measurement index of the ESD was established and the Pearson bivariate correlation analysis was used to explore the influencing factors. The results showed that the lower the quality of the irrigation water, the smaller the value of the ESD, which meant that the emitters were more likely to be blocked. Different irrigation water sources had different effects on the ESD, which were mainly caused by the characteristic size. Two dimensionless characteristic parameters (W/D and A(1/2)/L) are significantly correlated with ESD. Based on W/D and A(1/2)/L, the ESD prediction model was obtained and the accuracy could reach 86%. It could provide an accurate method for selecting emitters under different water source conditions, which is beneficial for the safe, efficient, and long-term operation of a drip irrigation systems using a low-quality water source.