IA rolls out 3 new, free irrigation tools

December 5, 2013 -  By

The Irrigation Association (IA) developed three new spreadsheets designed to assist irrigation designers and/or irrigation auditors. The tools are available for free download to all IA members.

Pipe sizing calculator

The IA pipe sizing calculator is a spreadsheet that assists landscape designers in sizing pipe in small systems as well as assists instructors in demonstrating the differences between the friction factor method and the velocity method for sizing pipe.

To use the tool, designers lay out a pipe network with up to 12 legs or pipe sections. Next, they designate the flow in each section, the incoming pressure and the allowable percentage of pressure loss. Users select whether their design will be based on friction or velocity. The spreadsheet picks the proper pipe size for the pipe section and shows the total friction loss in addition to the velocity and friction loss for each section. The pipe size for velocity and friction methods are shown side-by-side for comparison. Designers also may choose to override one of the methods to insert the pipe size of their preference. The spreadsheet calculates velocity and friction loss for the chosen pipe size.

Dripline calculator

The dripline calculator is based on the principles of soil physics and the standardized parameters for IA’s five basic soil classifications. It assists users in the design and layout of a dripline. Designers normally have to choose from a variety of row spacings, emitter spacings and emitter flow rates. Manufacturers give some guidelines, but the guidelines vary from one manufacturer to another. The dripline calculator allows users to input the soil type, row spacing, desired width of the wetted pattern, root depth, evapotranspiration and efficiency. In return, the spreadsheet recommends emitter spacing and flow rates.

Using this recommendation, users select the closest available emitter spacing and flow rate from a drop-down menu. The spreadsheet shows the application rate, the infiltration rate, the maximum time that the system can be run without having water penetrate deeper than the root zone, the recommended daily run time, and the run time necessary to achieve the desired width of the wetted pattern. If the selected values result in the application rate exceeding the infiltration rate, a warning message appears. Similarly, if the recommended run time to achieve pattern width exceeds the maximum daily run time, a warning message appears.

Irrigation scheduling calculator

The third spreadsheet is a modified version of the auditor spreadsheet. Users input site data and specific details about an audit, including run time, catch data and collector size. The distribution uniformity is calculated along with the precipitation rate and scheduling multiplier. That data is carried over to two commonly used scheduling methods: soil moisture irrigation schedule or watering days schedule. The user selects a time period for scheduling, important turf or plant information, and a soil texture category. The spreadsheet then calculates the important scheduling parameters (i.e., available water, plant available water and allowed depletion). The scheduling of the lower boundary and upper boundary are calculated, and the user selects the run time.

Site conditions that might dictate multiple starts are considered, but users also can input observed time to runoff. A scheduling summary is produced showing the water to be applied, the irrigation interval (in days), the cycle starts per day and the minutes per cycle. Similarly, the watering days schedule produces a scheduling summary, but the irrigation interval is constrained to whatever restrictions are placed on watering. The choices of restrictions are daily, every other day, every third day, every fourth day, every fifth day or once a week.

The tool will soon feature a destination diagram depicting a plot of depth versus area. The diagram will show the maximum possible efficiency given the distribution uniformity and will give a visual representation of under-watered and over-watered areas.

For more information about these tools, contact IA Education Director Bob von Bernuth at bob@irrigation.org.

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