Droplet size data from the sprinkler (R.C. 160-S) fitted with nozzles shapes square, rectangle, triangle and circle were studded in this work. A total 48 indoor tests were conducted. The pressure range was between 138 kPa (20psi) and 241.5 kPa (35psi) at 34.5 kPa (5 psi). Droplet size diameters were measured using the immersion method and Image Pro software. Nozzle pressure and shape had a major influence on droplet size. Higher pressure promoted smaller droplets over the entire application profile especially near the perimeter. Generally, the mean droplet sizes was larger for noncircular nozzles at a given distance from the sprinkler, but circular nozzle produced the largest droplet size at the outer perimeter of the pattern, that's because of long throw of circular nozzle than noncircular.

Sprinklers with circular and noncircular nozzles were tested to determine the water application patterns. Circular nozzles usually produced greater wetted radii than noncircular nozzles. Noncircular nozzles have the advantages of providing an acceptable water application pattern over the entire precipitation profile at low operating pressure. Noncircular nozzles (square, rectangular and triangular) were compared to circular nozzle for water application profiles with 100% overlapping. The over irrigation percentage was higher for circular nozzle than all shapes of noncircular nozzles.

Recently maintenance operation is considered one of the main axes of engineering management of pressurized irrigation systems. There for the aim of this research work was to select the most suitable maintenance programs to improve drip irrigation systems laterals performance, and decrease the damages caused by emitter clogging as a result of bad maintenance applications. The physical maintenance programs included lateral end flushing with two different operation times"5, 10 minutes at the end of each irrigation", at four interval times "weekly, Biweekly , monthly, and at the end of each season". The flushing 5minutes was applied once continuous, and the other intermitted. The systems performance was evaluated through three parameters: discharge, clogging, and pressure through seven evaluation criteria mentioned in the research. The results showed that biweekly flushing for 5 min. continuously (MS 1 P 1 2) proved to be the best flushing with fresh water program which decreases clogged emitters 44.21 % to be closer to the standard (control) with 4.85 %. Also partially clogged emitters decreased by 46.7 %, Emission uniformity(EU%) increased 19.4 %, and distribution uniformity(DU%) 13.9 % more than the control treatment. (MS 1 P 1 2) was followed by the weekly flushing for 10 min. continuously. (MS 3 P 1 1) as it raised (DU%) with 12.3 % and gave the highest value of pressure uniformity (UP%) that reaches 93.14%.

A finite difference numerical model was developed to determine the mean droplet size diameter at any distance from a sprinkler as a function of nozzle shape, size and pressure. Droplet size data from square, rectangle, triangle and circle nozzle orifice shapes verified the model. Data for model prediction were generated throughout lab experiments. Nozzle pressure and shape had a major influence on droplet size. Higher pressure promoted smaller droplets over the entire application profile. Noncircular nozzles had a large droplet size at the same distance from sprinkler but circular nozzle had the largest droplet size near the perimeter.

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