Review

Irrigation Science

, Volume 26, Issue 6, pp 451-458

First online:

Emitter discharge variability of subsurface drip irrigation in uniform soils: effect on water-application uniformity

  • M. GilAffiliated withDepartment of Rural Engineering, E.T.S.I Agrónomos Universidad Politécnica de Madrid Email author 
  • , L. Rodríguez-SinobasAffiliated withDepartment of Rural Engineering, E.T.S.I Agrónomos Universidad Politécnica de Madrid
  • , L. JuanaAffiliated withDepartment of Rural Engineering, E.T.S.I Agrónomos Universidad Politécnica de Madrid
  • , R. SánchezAffiliated withDepartment of Rural Engineering, E.T.S.I Agrónomos Universidad Politécnica de Madrid
  • , A. LosadaAffiliated withDepartment of Rural Engineering, E.T.S.I Agrónomos Universidad Politécnica de Madrid

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Abstract

Emitter discharge of subsurface drip irrigation (SDI) decreases as a result of the overpressure in the soil water at the discharge orifice. In this paper, the variation in dripper discharge in SDI laterals is studied. First, the emitter coefficient of flow variation CV q was measured in laboratory experiments with drippers of 2 and 4 L/h that were laid both on the soil and beneath it. Additionally, the soil pressure coefficient of variation CV hs was measured in buried emitters. Then, the irrigation uniformity was simulated in SDI and surface irrigation laterals under the same operating conditions and uniform soils; sandy and loamy. CV q was similar for the compensating models of both the surface and subsurface emitters. However, CV q decreased for the 2-L/h non-compensating model in the loamy soil. This shows a possible self-regulation of non-compensating emitter discharge in SDI, due to the interaction between effects of emitter discharge and soil pressure. This resulted in the irrigation uniformity of SDI non-compensating emitters to be greater than surface drip irrigation. The uniformity with pressure-compensating emitters would be similar in both cases, provided the overpressures in SDI are less than or equal to the compensation range lower limit.