Understanding the distribution characteristics of an individual irrigation sprinkler or spray nozzle is necessary to improve the uniformity of any sprinkler system.Relevant factors affecting the improvement of the irrigation performance of sprinkler systems are the engineering factors (i.e. operating pressure, riser height of sprinkler / nozzle, sprinkler type, deflector plates, and nozzle diameter), and the climatic factors (i.e. wind speed, air humidity and air temperature). It is important to highlight that this study has been focused on center pivot sprinkler irrigation system as it is the widely used sprinkler irrigation system in new lands of Egypt ( Toshka, Sinai and Nobaria).Therefore, five different types of spray nozzles, used on center pivot irrigation system, have been tested and evaluated. Several outdoor single-sprinklers and overlapped - sprinklers irrigation tests have been conducted for determining: water application rate, uniformity of water distribution, and application efficiency, under different engineering and climatic conditions.
Various sprinkler types - pressure -riser height combinations were used and the variation of application rate and weather conditions (i.e. air temperature, relative humidity, and wind speed) were measured during the test. A statistical approach has been used with these data to estimate water distribution uniformity coefficient CU, and water application efficiency AE, using a linear model. CU, and AE as sprinkler irrigation performance parameters, were estimated as functions of the sprinkler type, nozzle characteristics, riser height, operating pressure, and wind speed. Other climatic and engineering factors were not of significant effect on the CU or AE in this study. The model can be a useful tool to select the operational conditions (e.g. working pressure, riser height, nozzle type)
that can be suitable for certain environmental conditions ( air temperature, relative humidity, etc.) to improve water distribution uniformity CU and water application efficiency AE.