A field performance evaluation of drip emitters: pressure versus discharge

  • Khumoetsile B. Mmolawa


Field evaluation of irrigation systems (drip) can form a basis for decision making as to whether the irrigation system needs rehabilitation, overhaul or even dismantling if found to be very uneconomical. A comprehensive field evaluation of irrigation systems involves determining the overall efficiency of the system, for example, determining water use efficiency, field operating efficiency and water management practices in use. However, the objective of this study was to evaluate the operating pressure–discharge relationship for Naan-tif emitters against their manufacturer's recommended pressure-discharge relationship. Three fields in the Gaborone region (Kumakwane, Thamaga, Legotlhong ) were selected for the evaluation. Naan-tif emitters at these fields were evaluated by measuring discharges (volumetric method) from emitters at field operating pressure. The results show that all the Naan-tif emitters evaluated at the three farms had higher average discharge as compared to the manufacturer's recommendation at the field operating pressure. In conclusion, besides pressure fluactuations, clogging of emitters due to poor water quality and poor management practices can also cause emitters to perform outside recommended pressure and discharge values.

(Botswana Journal of Technology: 2002 11(2): 54-57)

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eISSN: 1019-1593