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ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #99795
Title: MODELING DISTRIBUTION UNIFORMITY FOR MOVING IRRIGATION SYSTEM WITH SMALL SPRAYING NOZZLES

Author
item OMARY, MOHAMMAD - UNIVERSITY OF CA
item Sumner, Harold

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/23/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: The effectiveness of an irrigation system for applying pesticides depends on several variables such as water flow rate and nozzle spacing. A model and computer program were developed to calculate water application depth and uniformity of a center pivot irrigation system equipped with small spray nozzles. Data collected from static distribution patterns from a single spray nozzle were used with moving irrigation system inputs, including spray nozzle spacing, moving velocity, cycle time, and percentage of moving time, in a computer program to determine desired irrigation depth and uniformity. Data collected to validate the computer program indicated that the model predicated 98.4 percent of the measured uniformity and water uniformity was 14 percent better for a cycle time of 30 sec than for a cycle time of 60 sec. This computer program can assist engineers in irrigation system design to determine spray nozzle spacing, flow rate, and cycle time to provide good water distribution and desired irrigation depth

Technical Abstract: A model and computer program were developed to calculate water application depth and uniformity coefficient for small spray nozzles mounted on a center pivot irrigation system. The program requires two basic inputs. First, the experimental data for the static distribution pattern of the spray nozzle, including collection time, spacing between collection cups, cups opening radius, and volume of water collected in the cups at a specific pressure and height are required. Second, irrigation system inputs including spacing between spray nozzles, distal end tower moving velocity, distance of spray nozzle from the pivot, move stop cycle time, or cycle time, and percentage of moving time are needed. The outputs are water application depth and uniformity coefficient. Experiments were conducted to validate the simulation for various moving velocities, spacing between spray nozzles, cycle times, and percentage of moving time. Results showed the uniformity coefficient of water distribution was 98.4 percent of the predicted coefficient and that by changing cycle time or percentage of moving time, the uniformity coefficient was improved by as much as 14.2%.