Anti-clogging evaluation for drip irrigation emitters using reclaimed water

Emitter clogging has a direct impact on the required operating time and benefit of a drip irrigation system, especially when using reclaimed water. Thus, accurately evaluating its anti-clogging ability is important to select an appropriate emitter under specific conditions. In his paper, a drip irrigation emitter clogging experiment was carried out, and the dynamic outflows of 14 emitter types using 3 kinds of reclaimed water and the groundwater in the experiment station in Tongzhou, Beijing, were tested. Then, the drip irrigation emitter anti-clogging ability evaluation index (Ia) was proposed, based on the measured emitter clogging characteristics. Ia ranked in consistent with average discharge variation rate (Dra) among different types of emitters. Thus, Ia is a valid performance indicator to evaluate anti-clogging ability, and an emitter with a relatively large value of Ia has a better anti-clogging ability. According to the calculated Ia, the same type of emitter showed better anti-clogging ability with the groundwater than with the reclaimed water, while cylindrical emitters were more likely to clog than flat emitters. Additionally, Ia was mainly affected by flow path length (L), flow path width/depth ratio (RW/D) and average near-wall water shear force (τ), as Ia increased with shorter L, smaller RW/D and larger τ. Furthermore, the quantitative estimating model of Ia was established through dimensional analysis and was predicted by an emitter’s rated outflow (Q) and flow path geometrical parameters (L, W and D).