The authors are appreciated for presenting a rapid prediction method of hydraulic performance evaluation for emitters with labyrinth channels. In that procedure, a variable pressure loss coefficient (PLC) was proposed as the evaluation index of an emitter's hydraulic performance. As a matter of fact, the authors' previous work (Zhang et al. 201 1b) was focused on the same concern with testing the hydraulic performance of specific types of emitters with labyrinth channels. In that procedure (Zhang et al. 201 lb), the combined pressure loss coefficient (PLC) was also proposed as an evaluation index which incorporates the effects of frictional and local losses in labyrinth channels. Regarding the same concern, Zhang et al. (2011a) proposed an alternative procedure for testing hydraulic performance of three of the most commonly available high-head in-line drip-tape emitters under different working-head conditions ranging from 0.2 to 10 m, especially for low-head conditions. This analysis (Zhang et al. 2011a) mainly deals with the calculation of the coefficient of manufacturing variation (Cv) and the emitter flow exponent (x), regarding different phases of water pressures. For the design problem of testing emitter hydraulic performance, these three successively published procedures (Zhang et al.
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