The name of the irrigation game today is conservation. Conserve water. Conserve energy. Conserve labor and maintenance.

The approaches are many and varied. Technical papers, magazine articles and literature have provided us with a great deal of information on how to accomplish conservation while continuing to design and maintain acceptable landscapes. A great deal of that information is devoted to changing our ways of thinking about irrigation and to detailing the hardware and techniques to employ these new ideas.

As one of these primary forces, low volume irrigation has already become an accepted way of life in many areas for many applications. Drip emitters, low volume bubblers, and mini or micro sprinklers have done much to convert our concepts of overall watering to the spot placement of water only where it is needed in beds at the root zones of ornamentals and trees or in limited low volume areas of groundcover or color. Installation techniques and details have been devised to help insure permanency, efficiency and vandal resistance of these systems.

The gradual acceptance and growing understanding of the concepts of low volume irrigation are contributing to increased efficiency in most landscaped areas other than turf. Low volume subsurface irrigation systems under various turfgrasses have been tried for years with unsatisfactory results, especially in areas that do not receive supplemental rainfall during the irrigation season. Studies in Florida, California and Georgia have confirmed these conclusions in the past. Continuing long-range tests with the latest subsurface equipment are now underway at the Center for Irrigation Technology (CIT) at California State University in Fresno, California. Research results are not expected for another two to three years.

Until subsurface or other technologies can be proven effective for irrigation of turfgrasses, we must still be dependent on sprinklers for the maintenance of turf areas. The secret of success (including efficiency) of sprinkler irrigation for turfgrasses is uniformity of coverage. It’s an accepted fact that a turf sprinkler system will be operated long enough to apply the minimum water requirement to the weakest spots in the system. The greater the uniformity of distribution, the less the need to overwater a large portion of the system to cover the few weak spots.

For most irrigation designers the design of a system for maximum uniformity has been primarily a judgment call. Most often the manufacturer’s recommended spacing for a given sprinkler is the basis for that best judgment. All too often those figures have been based solely on the concept of a percentage of the sprinkler’s throw or its diameter of coverage. Occasionally designers have obtained sprinkler profiles from manufacturers and laboriously worked out the accumulative precipitation rates for given spacings. A sprinkler profile is a graphic depiction of the distribution of water by a sprinkler from the head to the furthest point of throw, usually in the form of a graph.

A software program (for IBM and compatible computers) that analyzes data and provides the information required by a designer to make decisions on spacings and uniformity has recently been released by the Center for Irrigation Technology (CIT). This program, dubbed SPACE for Sprinkler Profile And Coverage Evaluation, has been developed for analyzing sprinkler patterns. It is a refinement of software as a part of the testing and evaluation program at CIT.

Unlike other software programs developed for irrigation management or for design and estimating assistance based on arbitrary sprinkler spacing and performance characteristics, SPACE uses actual test data to generate a coverage profile for a given sprinkler. That profile can then be used to perform appropriate uniformity and efficiency calculations on the simulated application pattern, including the popular densogram display and scheduling coefficient determination. The densogram is a visual display of uniformity in which light areas of coverage are projected as light areas on the screen pattern and the heaviest areas are darkest. The scheduling coefficient is a multiplier generated to determine run times foe systems that will apply adequate water to the lighter areas in the pattern.

Such software can be used for comparative purposes by determining the uniformity of coverage for various sprinkler, nozzle, pressure and spacing combinations including both triangular and rectangular configurations. Existing systems can also be evaluated. By placing catchments equally across a repeated coverage area and taking readings after a timed test, data can be placed in the program to evaluate the system uniformity.

The SPACE program from CIT is available as an independent program complete with a user’s manual. Also available is a companion disk containing ClT’s file of independent test data on some 200 sprinkler patterns. Interested parties may also subscribe to receive semiannual updates of a sprinkler data file containing the most recent results on all makes and models of sprinklers tested. For information contact: Center for Irrigation Technology, Cal State University, Fresno, CA 937-400-0981.

At least one other similar software program is under development. Hunter Industries now uses software that is almost identical and may, in fact, be made compatible with the SPACE program. We understand that other programs of the same type are, or will soon be under development.

This family of computer programs for irrigation could be the foundation upon which many others may be built. The knowledge of computer generated spacing patterns for maximum uniformity of distribution based on individual sprinkler profiles can be easily applied to other software programs for system design. It can be proven that some sprinklers with certain types of profiles can be spaced farther apart, retaining maximum uniformity at a lower precipitation rate. All of this information can be joined to create efficient irrigation systems from test proven facts without the laborious calculations and comparisons previously required.

For irrigation consultants and designers, the benefits of these programs should be obvious. Not so obvious, however, is the potential for use by those who must evaluate irrigation systems for adequacy and, hopefully, efficiency. Just think of the simplicity and accuracy of plugging in the planned spacing and the profile of the specified sprinklers and receiving an immediate feed back of precipitation rates and uniformity of distribution, along with a visual densogram display and a scheduling coefficient.

Chet Sarsfield has been in the irrigation industry for 40 years. He is the owner of Irrigation Technical Services and one of the founders of the ASIC. Sarsfield is an honorary member of the ASIC and CLCA. He also is a member of ASAE, ALCA, NCTC, SCTC and the IA. He has served The Irrigation Association as a director and chairman of the landscape irrigation committee, planning council and public affairs committee and as a member of the Certification Board of Governors.