## Economic design of a sprinkler turf irrigation system

##### Abstract

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.