A comprehensive irrigation audit can help golf facilities save substantially on water usage and cost. Photos by Michael D. Vogt
Few people would welcome an IRS audit, but you might want an irrigation audit. These audits can be beneficial in golf course water savings, power savings and irrigation equipment longevity and could result in better all-around turf conditions.
It’s impossible to see where all the water goes after it leaves the sprinkler head and to what degree distribution uniformity is achieved. A well-designed and maintained watering system will deliver a uniform amount of water throughout its irrigation
pattern, thus eliminating wet and dry spots.
However, even the best sprinkler/nozzle combinations fall short of perfect uniformity. Watering systems with poor uniformity must apply greater volumes of water to an area to achieve the same results as a system with good uniformity, most often resulting
in a wet golf course, especially later in the irrigation season. Sprinklers typically used on golf courses fall into three categories as identified by the Irrigation Association’s Certified Golf Irrigation Auditors manual. These are:
- 80% or greater distribution uniformity (excellent, achievable).
- 70% distribution uniformity (good, expected).
- 55% or less distribution uniformity (poor).
Golf course irrigation system audits
Many golf courses decide to perform audits to discover how much water is being applied to the course — and where. An irrigation audit is a thorough analysis of the operation of this complex system of water delivery on modern golf courses.
A comprehensive audit covers the following:
- Water supply.
- Pumping system(s).
- Piping system.
- Pipe fittings.
- Valves.
- Sprinklers.
- Control system.
- Management practices.
- Water distribution.
Irrigation audits are effective in documenting irrigation system efficiencies, and a well-written report can be an excellent tool for communications to members, boards of directors, committee members and owners to better understand one of the superintendent’s
most important and complex tools.
Members and owners seldom see the irrigation system. An audit will help them understand the significant investment, maintenance expense and operational cost of one of the largest, most complex systems on the course.
Part of the audit entails the use of catchments to determine distribution uniformity.
Distribution uniformity
Distribution uniformity (DU) is a critical measure of the irrigation system’s ability to apply water uniformly to the turfgrass. A value of 100% represents perfectly uniform coverage of water to a predetermined area; however, perfect uniformity
never occurs, even with rainfall.
For golf course irrigation audits, DU is generally calculated by identifying the volume of water that is applied to the driest 25% of the test area and dividing it by the average volume throughout the test area. This is also expressed as the lower-quarter
distribution uniformity or DULQ.
DULQ is an important component of the audit and points out the areas of low efficiency in order for a plan to be formulated and to begin to address irrigation system flaws, saving water and power and improving playing conditions and turf health through
drier surfaces.
DULQ is calculated through the use of catchments (collection devices). Each catchment that is used in the test must have the same opening area or “throat” and must be stable enough that it cannot be relocated or knocked down by operating sprinklers.
The proper placement of catchment devices is critical in conducting a water-distribution audit. The catchments should be placed in a grid throughout the entire target audit area.
The system check
Before the catchments are placed for the DU test, a simple system check is required. This check includes:
• Sprinkler check: Activate each sprinkler in the test zone to inspect and correct any tall grass around the sprinkler. Sprinklers should be level and free of physical damage that needs attention.
• Nozzle check: Make sure proper nozzles are used. Also, be certain that nozzles are not cracked, broken or otherwise distorted.
• Conditions check: The audit should be conducted under normal system operating conditions. Normal irrigation run times are in the evening, when wind conditions are less pronounced. As a rule, audits should not be performed with
wind conditions that exceed 5 mph.
• Pressure check: The water-delivery system should be tested for pressure at the zone being calculated. Pressure checks should be performed on static pipe and with sprinkler operation. Both pressures should be recorded. System
pressure can dramatically affect DU. Proper pressures can be adjusted at the head in some cases; the manufacturer’s specifications for nozzle size should be followed.
• Document: Sketch a map of the zone to be tested. Use an existing drawing if available. Show all sprinklers, nozzle type, rotation arc, model number, operating pressure and pairings if wired to operate together with other sprinklers.
Sample golf irrigation scheduling worksheets for systems with 62% (top) and 83% (bottom) DULQ.
Lay out the catchments, begin DU test
After the above system test, the actual DU catchment test can be performed. The catchment devices should be placed in a grid sequence 12 to 15 feet apart.
Run sprinklers in a normal sequence that would simulate an irrigation event for the unique zone being examined. The minimum time prescribed for the DU test is 15 minutes so that the catchments can accumulate sufficient water for measuring. All sprinklers
in the test zone should run for an identical time.
Record the volumes on the site map of each catchment and perform the calculations.
DULQ can be calculated by the average volume of the lower quarter of catchments times 100 divided by the total average of catchments, or:
DULQ = (average of lower quarter catchments x 100)/average of all catchments
Remember:
- 80% or greater distribution uniformity (excellent, achievable).
- 70% distribution uniformity (good, expected).
- 55% or less distribution uniformity (poor).
What does DULQ really mean?
DULQ is a percentage that can be calculated into what is referred to as a run-time multiplier (RTM). This number factors in a given value that indicates you must run your tested portion of the irrigation system a multiple of X to get proper coverage in
the driest spots.
Once all the data is collected, a golf irrigation scheduling worksheet can be constructed. Figures 1 and 2 are sample worksheets for a course with 62% or 83% efficiency. Based on the two examples, the savings in water for the more-efficient system would
be:
That’s a savings of 150,000 gallons on just this one green. Now, multiply the number of gallons times the number of greens. The number of gallons is substantial. Based on 19 greens at an average course, that’s a whopping 2,850,000 gallons
— just on greens. But also notice in the examples in figure 1 and 2, the precipitation rate (PR) increased by 0.04 inches per hour on the 83% DULQ green. We’re applying less water time at a slightly higher PR. Note: That’s if you
could increase efficiencies by 21%. In most cases, older systems cannot achieve these efficiencies.
The irrigation audit bottom line
By auditing the irrigation system, a superintendent can find additional savings in water, power and system life. An irrigation audit and a good irrigation system maintenance program always pay for themselves.
Select only a Certified Golf Irrigation Auditor (CGIA). They know golf courses and the workings of a complex golf irrigation system. Also select an auditor who has no affiliation with a company that sells irrigation supplies. An auditor with no bias will
ensure a proper audit takes place without regard to furthering his or her business.
After the audit is performed, map out an action plan based on recommendations from the CGIA, and let the local community know that the club is concerned with the area’s water resources — concerned enough to keep water consumption to a minimum
through careful management of water, and additionally, the use of electric power.
The overall efficiency of the irrigation system is dependent on the golf superintendent’s devotion to protecting natural resources. The best-operated and best-maintained irrigation system a superintendent can attain is an end to that goal.
Michael D. Vogt, CGCS, CGIA, is a GCSAA Lifetime Member who has been a member for 48 years. A Penn State graduate and former president of the Illinois Turfgrass Foundation, Vogt received the foundation’s Distinguished Service Award in 1990. He currently
serves as capital asset manager for Club Benchmarking.