Existing Problem: A Standard 27 degree Trajectory Gun with a Ring Nozzle

The base system for the comparison includes a traveler system with a 1,000 ft hose. The base system has speed compensation and an efficient water delivery system. A standard 27 degree trajectory gun with a ring nozzle is in use. The suggested alternative is to replace the gun assembly and change to an 18 degree trajectory tapered bore nozzle. The lower trajectory will not throw water as high resulting in less evaporation during application. A tapered bore nozzle must be used to provide the same overlap and uniformity of coverage at the lower discharge trajectory angle.

Water Conserving Practice: 18 degree trajectory tapered bore nozzle.

¹Potential No. of Irrigation Systems Affected	1200
Estimated Water Savings (%)	5 (0 to 10)
²Average Year Water Savings (million gal.)	969
³Dry Year Water Savings (million gal.)	1662
Est. Cost of Full Implementation on Avg. System ($, 1998)	$1,500
Statewide Costs for Full Implementation ($, 1998)	$1,800,000
Cost / Unit of Water Saved in Average Year ($, 1998 / million gal.)	$1857

Estimated water savings for this alternative range from 0 to 10 percent with an average of 5%. Greater savings will result if larger nozzles with higher operating pressure are converted. Time of day application would also affect savings with greater savings realized on those systems operated predominately during daylight hours.

Of the 4,000 traveler systems currently in use, approximately 1,200 could benefit from this modification. The potential water savings would be 969 million gallons annually on average, and 1,662 million gallons in a dry year. The average system costs for this modification is $1,500. With full statewide implementation, the total cost for 1, 200 systems would be about $2.8 million with a water savings cost/benefit ratio of about $1,857 per million gallons saved.

Source: Evans, R.O., K.A. Harrison, J.E. Hook, C.V. Privette, W.I. Segars, W.B. Smith, D.L. Thomas, and A.W. Tyson. 1998. Irrigation conservation practices appropriate for the Southeastern United States. D.L. Thomas (ed.) Geologic Survey Project Report No. 32. Georgia Geologic Survey, Georgia Department Of Natural Resources, Environmental Protection Division, Atlanta, GA 30334. 43p.