Analysis of water application with semi-portable big size sprinkler irrigation systems in semi-arid areas

• This experiment characterizes the distribution of water on semi-portable big size sprinkler systems.
• Evaporation and drift losses in semi-arid areas have been modelled.
• The proposed modelling equations use operating pressure, wind speed and vapour pressure deficit.
• Irrigation uniformity has been analysed depending on the climatic parameters and the design characteristics of the system.
• To suggest different recommendations for helping about the management of sprinkler irrigation systems.

Sustainability of irrigated agriculture depends heavily on getting a high efficiency application for the irrigation. It is very important to understand the factors that affect to irrigation uniformity and discharge efficiency, especially using semi-portable big size sprinkler. There are not studies conducted with big size sprinklers which work on high flow rates and big layouts spacing. In this paper, the spray losses (Ls) and water distribution of sprinkler irrigation system with semi-portable big size sprinkler on semi-arid areas have been characterized. The factors affecting on discharge efficiency and irrigation uniformity were analysed (working pressure, irrigation layout and weather conditions). The field tests were conducted in outdoor conditions with a single sprinkler system. Six predictive equations were obtained to estimate drift and evaporation losses. The proposed equations use operating pressure, wind speed and vapour pressure deficit. The results show an increment of 3.26% for Ls for each increment of 1 m s−1 of wind speed. Spray losses rise up to 22.7% at 450 kPa operating pressure when wind speed and vapour pressure deficit increased up to 4.2 m s−1 and 6 kPa, respectively. A significantly effect of wind is appreciated on the spray losses and water distribution pattern under different conditions with regard for working pressure and sprinkler spacing. This behaviour is very similar to obtained with medium size sprinklers. Technical criteria can be used to optimize irrigation management according to the design factors and the climatic parameters.