Economic design of a sprinkler turf irrigation system

A study was conducted to determine the economic feasibility of adjusting sprinkler overlap to obtain higher uniformity coefficients and ultimately higher water application efficiencies. To calculate the total system costs needed to complete an economic analysis for this study, several turf irrigation system designs were carried out. For this study, an area of dimensions 45 ft x 90 ft (Area 1} and an area of dimensions 600 ft x 400 ft (Area 2} were chosen to represent a typical small and large area, ~espectively. The following square spacing scenarios were chosen for Area 1: (1}15 ft x 15ft and (2}22.5 ft x 22.5 ft. the following square spacing scenarios were chosen for Area 2: (1} 20 ft x 20 ft, (2} 40 ft x 40 ft and (3)50 ft x 50 ft. For each of the five spacing scenarios, different sprinklers were chosen to represent various overlap situations. Once the sprinklers were chosen, the total system cost for each spacing scenario and each overlap situation was calculated. Included in the total system cost were the following: (l}sprinkler heads, (2}piping, (3)valves, (4}backflow preventers (Area 1 only) and(S)water costs. The total system cost was plotted against spacing to wetted diameter ratio (overlap} . The plots were analyzed with a curve fitting computer program (LOOK) developed by Dr. Gregory at Texas Tech University, Department of Civil Engineering. The computer analyses showed that for Area 1 there seemed to be no significant correlation between total system cost and sprinkler overlap. However, for Area 2, computer analysis of the data showed a definite correlation between total system cost and sprinkler overlap. The data best fit a typical power function Y = Al * EXP(A2 *X). The trend showed an increase in total cost as the ratio of spacing to wetted diameter increased or overlap decreased.