The hydraulic performance of large-diameter gated fluming, commonly used in furrow irrigation, was investigated using computational fluid dynamics (CFD). The continuity and the momentum equations governing the fluid in the system were solved numerically for a steady incompressible and turbulent flow using a realizable software model. The CFD results were compared with the laboratory measured results and those obtained using a hydraulic simulation model. The CFD results showed a good correlation with the measured data and those generated using the software. The velocity head in the pipeline had no influence on the magnitude of the outflows possibly due to the unique shape of the outlet. The pressure head recovery across the outlets was greater than the energy loss along the pipe; hence, the pressure and discharge increased towards the downstream end. The CFD approach was found to be an appropriate tool for detailed analysis of the hydraulic characteristics of gated irrigation pipelines.

The International Network of Irrigation Testing Laboratories (INITL) undertook a sprinkler intercomparison testing exercise to generate data for an objective comparison of the performances of the different facilities and identify opportunities for further improvements. Three impact sprinklers were tested in four laboratories in accordance with established standards. The plots of flow rate-pressure profiles were found to be consistent, and correlated to those obtained from previous studies. Although there were slight variations in the measured flow rate data, the mean flow rates at each pressure level were the same for the three sprinklers, and the shapes of the radial distribution profiles were similar. The deviations of reconstituted flow rates (from the measured) of at least two tests in each facility were found to exceed the recommended limit. The sprinkler software developed by INITL was found to have a good correlation with a related commercial software program.

The International Network of Irrigation Testing Laboratories (INITL) undertook a laboratory inter-comparison testing exercise of three sets of drippers in the period 2013 and 2014. The four testing facilities that participated in this exercise are based in following countries: Australia, Brazil, France and China. The objective of the testing programme was to compare results from different independent testing facilities to enable individual laboratories identify potential opportunities for improvement of their performances. This would also facilitate the INITL to make proposals for harmonisation of the testing methods. The maximum coefficient of variation, cᶹ, at the manufacturer's recommended operating pressure of 100 kPa, was found to be 3.76%, which was significantly smaller than the 7% recommended by ISO 9261 [5] as the maximum allowable variation of the flow rate of the test sample. The emitter exponent was determined to be approximately 0.5 which is consistent with results obtained from past studies. At the operating pressure of 100 kPa, it was found that although the average flow rates from the participating laboratories were similar, there was a difference in the dispersion of data. Datasets for the 4 Lh‾¹ dripper model fitted a normal distribution model, while on the other hand, some data sets for the 2 and 8 Lh‾¹ dripper models were not normally distributed. A higher dispersion of measurements can be interpreted as a higher instability of the testing conditions. The variance for the 2Lh‾¹ dripper model was found to be homogeneous, while non-homogeneous for the other two models. The latter implies that at least one of the laboratories presented an uncertainty of measurement significantly different from the others. The measurement uncertainty undertaken in this study demonstrated that there were opportunities to improve the measurement process. Recommendations and suggestions for harmonisation of test procedures and improvements in individual laboratories are also identified in this paper.

The catch can method is traditionally used for evaluating performance of drip systems. Two variations of this method are commonly applied in laboratory testing of drippers: the sequential and the simultaneous method. This study compared uniformity and measurement uncertainty of the two methods, with the overall aim of improving irrigation water management. The simultaneous method was found to have a lower coefficient of variation(Cν) and measurement uncertainty, indicating that it is more accurate than the sequential method. In all the tests, however, the Cν was determined to be <5%, which is acceptable as per the current reference standard.

Agriculture is by far the largest consumer of fresh water, contributing to approximately 70% of all withdrawals annually on a global scale. However, with the increasing human population, it is facing competition for the scarce water resources from domestic and industrial users. This has led to the promotion of irrigating methods, particularly the drip system, that are considered to be more water and labor efficient [10].

Surface irrigation methods are simple, mostly gravity driven and therefore have lower energy requirements. However, these systems are often seen as being inefficient both in labour and water usage. As the competition for the scarce water resources and greater emphasis on environmental conservation gain ground, more focus has been directed towards surface systems. On the one hand, some irrigators have converted to pressurised systems which are seen to be more water efficient. This is reflected in the decline of 28% of the proportion of irrigated land in Australia under surface irrigation in the last two decades and a decrease from 30 to 19% in the proportion of agricultural establishments using the system between 2002 and 2009. This trend has been corroborated by data obtained from US irrigation surveys. On the other hand, the surface system has experienced improvements ranging from upgrades of physical irrigation infrastructure and hardware to advanced management practices including computer simulation modelling. There are also emerging concepts and on-going research in surface systems that have the possibility to confer significant benefits to the users of these systems. Conversion of the irrigated land from surface to pressurised systems and the decline of the proportion of the irrigators using the system is expected to continue into the future. However the surface system will nonetheless remain important. Selected crops such as rice require to be grown using surface methods. There is also a chance that the rising energy costs might curtail the adoption of pressurised systems.