Hydraulics of large diameter gated flexible fluming

Gated flexible or “layflat” fluming is used in furrow irrigation to supply water to individual furrows. Laboratory experiments were conducted to establish the flow characteristics of these pipes under the low heads and high flow rates typical of furrow irrigation of cotton in Australia. Two different diameters of layflat were used in the study, 222.8 and 425 mm. Proprietary 50 mm diameter outlets (gates) were installed in the layflat at 1 m spacings. Tests were conducted at various pressures and flow rates to determine; the geometric characteristics of the fluming and their relationship to pressure, the friction loss coefficient for the fluming with and without the outlets installed, and the head-discharge characteristic for the outlets. It was shown that the fluming is capable of supplying the desired flow rates (about 6 l s−1 per furrow) at pressure heads