HYDRAULIC PERFORMANCE OF LOW PRESSURE DRIP IRRIGATION APPROPRIATE FOR SMALLHOLDINGS

Abstract

The objective of this study was to analyze the hydraulic performance of low-pressure drip irrigation system on emitter discharge, coefficient of variation, emission uniformity and friction losses. Therefore, a laboratory and field experiments were conducted to assess the hydraulic performance of three drip lateral types [Gr (4 Lh-1/30cm), Flat-tape (2 Lh-1/30cm) and T-tape (10 Lh-1/m)]. Discharge rates were measured at four different low- pressure heads (0.4, 0.6, 0.8 and 1 bar). Results show that the discharge of emitter is increased with increasing pressure and decreasing of lateral length, which implied that the combination between pressure and lateral length has a direct impact on the emitter's hydraulic performance of low- pressure drip irrigation systems. Consequently, the low operating pressure combined with short laterals resulted in the emitters produce the desired discharge with good performance parameters. As well as, high emission uniformity coefficient (90-97%) was observed at 30 and 40 m lengths for all lateral types and all operating pressure. For the types of Flat-tape and T-tape with a length of 50, 40, and 30m, all values of friction losses were acceptable at different operating pressures. The use of a low operating pressure less than1 bar indicated that it was an excellent operation condition in spite of that it was greater than the operating pressure in the range recommended by this dripper manufacturer. Furthermore, the use of low-pressure drip irrigation systems using the combination of low pressure and short laterals would reduce the energy requirements of operating smallholdings irrigation system.