Evaluating engineering parameters affecting irrigation efficiency with particular reference to trickle irrigation systems

Abstract

The current study was carried out at Nubaria Research Station. Seven emission devices extensively used in trickle irrigation system were hydraulically characterized under laboratory conditions. The types ofthe tested emitters were as the following: A: labyrinth- long path, B: orifice, C: orifice-vortex, D and E: spiral- long path, F: self-flushing, compensating-long path and G: self-flushing, compensating-orifice. Tests were conducted under different operating pressures ranging

from 50 Kpa to 350 Kpa for types A, B, C, D and E. This range was extended to 500 K.Pa for compensating emitter types F and G. The coefficient of manufacture variation C.V was calculated and plotted against pressure. Then emitters were classified based on ASAE and ISO- standards. Results showed that emitter E was with the highest values of C.V followed by emitter B, D and F whereas emitters A, C and G were characterized by lower values of this factor. Data showed also that the C.V value varied with pressure. The discharge exponent of the flow rate and operating pressure head equation was found and used to evaluate the emitter flow sensitivity to pressure. The lower the value of x, the more pressure- compensating device is. Emitters A, B and C were categorized as turbulent flow, non­ pressure compensating, whereas both emitters D and E were classified as partially turbulent flow, non- pressure compensating types. On the other hand, emitter F was categorized as compensating type while, emitter G was fully compensating one.