Effects of drip irrigation circuit design and lateral line lengths: I—On pressure and friction loss

Abstract

Laboratory tests were conducted at the Irrigation Devices and Equipment’s Test Laboratory, Agricultural Engineering Research Institute, Agriculture Research Center, Giza, Egypt. The experimental design of laboratory experiments was split in randomized complete block design with three replicates. Laboratory tests carried out on three irrigation lateral lines of 40, 60, 80 m under the following three drip irrigation circuit (DIC) designs; 1) one manifold for lateral lines or closed circuits with one manifold of drip irrigation system (CM 1 DIS); 2) closed circuits with two manifolds for lateral lines (CM 2 DIS), and 3) traditional drip irrigation system (TDIS) as a control. The aims of the work were to study the effect of drip irrigation circuits (DIC) and lateral lines lengths (LLL; where): (LLL 1 = 40 m, LLL 2 = 60 m, and LLL 3 = 80 m) on pressure head (PH) and friction loss (FL). Regarding to LLL and according to PH values, DIC designs could be ranked in the following ascending order: TDIS < CM 1 DIS < CM 2 DIS. The differences in PH among DIC designs were significant at the 1% level. The depressive effects of LLL on PH could be ranked in the following ascending order: LLL 1 < LLL 2 ≤ LLL 3 . Differences in PH among LLL treatments were significant at the 1% level except that between LLL 2 and LLL 3 . The effects of interactions among: DIC × LLL on PH were significant at the 1% level with some exceptions. The highest value of PH (9.5 m) and the lowest one (6.05 m) were achieved in the interactions of CM 2 DIS × LLL 1 and TDIS × LLL 3 , respectively. The shapes of the energy gradient lines were affected by DIC and LLL treatments used through their effect on ?H/H ratio. However, they followed similar trends. According to the FL values, DIC and LLL treatments could be ranked in the following descending orders TDIS > CM 1 DIS > CM 2 DIS and LLL 1 > LLL 2 > LLL 3 . The differences in FL among DIC and LLL were significant and the effects of interactions among DIC × LLL on FL were significant at the 1% level. The maximum and minimum values of FL were obtained in the interactions: TDIS × LLL 3 and CM 2 DIS × LLL 1 , respectively. Therefore, the CM 2 DIS system is recommended for use where technically feasible.