Golf Course Irrigation System Design
Start with the fairways first then design greens and tees
Fairway design should include
Sprinkler models
Total gallons per minute needed
Pipe sizes
Solving for average fairway width
Single-row or multi-row?
Reduce the number of different sprinkler models
Select the proper sprinkler size and model
Determining average fairway width
Use good judgment
Avoid measuring diagonally across fairway
Average width= total average width of all fairways/total number of fairways
Solving for effective coverage
Talk about sprinkler head coverage explain
See figure2.4
Sprinklers are uniform to about 65% of diameter to almost nothing at the edges
Figure 2.5, 2.7, 2.9
Table 2.1
Sprinkler selection
Average fairway width and effective coverage desired
Sprinkler effective coverage
Is the relation ship of the amount of or depth of water obtained at a given distance from
the sprinkler That is:
Sprinkler head_________30ft_________50ft____60ft________80ft_______100ft
1in
.75in
.5in
.25in
0in
Desired effective coverage
Is the amount or depth at a given distance from the sprinkler
Figure 2.10 and 2.11
A effective coverage of 70% of diameter is good
Table 2.2
Sprinkler models and performance characteristics
Base Pressure (PSI)
Discharge Rate (GPM)
Diameter or radius (FT)
Precipitation rate (in/hr)
Maximal spacing, one row (FT)
Nozzle sizes (in)
Check out your catalogs
Pressure
The distance or diameter of coverage with a specific nozzle depends on the pressure at
the nozzle itself
When water is discharged pressure head is converted to velocity head which sends water
away from sprinkler
If the nozzle size increases (from wear) and pressure stays the same precipitation rates
will increase
However larger nozzles(from wear) will increase flow which will increase friction loss
which will in turn reduce pressure thus reducing coverage of the sprinkler
Pressure variation vs. sprinkler discharge
A 20 percent variation in base pressure (PSI) will result in a 10 percent variation in
sprinkler flow (GPM)
Part circle sprinklers
Compare part circle with full circle heads
In smaller turf situations part circle and full circle heads can be placed in the same zone if
the precipitation rates are matched
However in large turf situations part circle heads and full circle heads are placed on
different zones
Other factors to consider during the design process
Wind
Use the smallest practical radius off throw
Use the lowest trajectory angle 32 degrees is ideal but 22 to 27 degrees gives optimal
radius while minimizing water application distortion
If average wind speeds exceed 5 mph heads should be spaced closer together
Slope
Heads should be perpendicular to the slope being irrigated
Precipitation rate should not infiltration rate
Spacing across the slope should be reduced when the slope exceeds 10 percent
Up and down the slope the radius is longer going down and shorter going up
Factors to consider for sprinkler selection
Models meet your requirements
How reliable is your distributor
Mid range pressure should be selected
Performance will differ from catalog
Do not mix different types of sprinklers on the same circuit
Application rates must be the nearly the same between sprinklers
Full circle, half circle, quarter circle heads should have matched precipitation rates or be
placed on different circuits
Operating pressure should be uniform
Pressure variation to be with in 20 percent
Solving for Sprinkler Spacing
Single row
You need to know how far a sprinkler can be spaced and still do an efficient job under
normal conditions
Spacing
Figure 2.17
Resulting distribution with overlap
Figure 2.18
Wind spacing
Figure 2.19 and 2.20
Single speed vs. 2 speed sprinklers
The recommended spacing for single row sprinklers is head to head 50% spacing or
plateau-to-plateau 60% spacing
Explain figure 2.21 and 2.22
Solving for the total number of sprinklers to cover all fairways
Use a compass or circle template set to scale to represent the spray diameter of the
sprinkler selected
You the designer are responsible to properly space and to cover the fairways accordingly
After you complete the coverage it is just a matter of counting the heads
How to do it:
Start at greens
Do not let circle touch the putting surface
Location of the first fairway sprinkler from green the edge of first head’s radius should be
10 feet from the green Explain why
Often you want better coverage near the green (approach area) so 2 heads in the is area is
just fine
Coverage of wide fairways areas
Use double row design refer to chapter six page 125-130
Solving for rate of water application (inches per hour)
Can not do for one sprinkler because water distribution varies
Figure 2.33 and 2.34
In a single row in the overlapped areas
96.3 x gpm (1 sprinkler)
In/hr = ---------------------------------Spacing (% diameter) x 80% diameter
Do sample problem
For a double row design using square spacing precipitation rate is determined:
gpm (one head) x 96.3
In/hr = ---------------------------------SxL
Where: S= spacing (ft) sprinklers on line
L= spacing (ft) between lines
Sample problem