Old 05-04-2014, 07:52 PM
OttoIrrigation OttoIrrigation is offline
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MP Rotators and Wind Speed

Assume Hunter MP Rotators are installed "by the book" according to Hunter for turf irrigation on a residential site. Assume a mix of zones, some with MP1000's, some with MP2000's, some with MP3000's, and some with MP3500's. Assume irrigation controller has access to wind conditions (sustained wind speeds, gust speeds, and wind direction) on site through a Davis Weather Station or similar. Assume irrigation controller can also read one or more soil moisture sensors located in the turf's root zone.

Broadly speaking, at what wind speeds should scheduled irrigation be either 1. deferred until less windy or 2. modified (if deferral inadvisable because of soil moisture level) to compensate for wind conditions.

I realize there's going to be a lot of "it depends" in the answer (e.g. "It depends on the radius"), so rather than splitting hairs or building a computer simulation, at this point I'm just interested in getting a rough idea from those who have experience with the MP Rotators under various wind conditions.
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Old 05-05-2014, 09:17 AM
Kiril Kiril is offline
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Location: District 9 CA
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You can't reasonably do it for gust speeds, only for sustained wind speeds. I would probably set the threshold somewhere around 12-15 MPH sustained wind speed in order to be reasonable assured you will be able to irrigate when you need to at the appropriate time of day. At this wind speed you will get some pushing around of the stream, but it won't be really bad. Ideally you would want suspend irrigation when sustained wind speeds are in excess of 8 MPH, but I feel that would be too restrictive with respect to water windows at the appropriate time of the day. At speeds up to 8 MPH, the MPRotator does a good job of maintaining DU, and certainly far better than any type of spray nozzle.

That all said, you will need logic to determine when the need to apply water overrides the desire to prevent wind drift. I would probably look to set an absolute upper threshold for all sprinkler type irrigation to be suspended regardless of current soil moisture, say 20 MPH, then work your way down from there based on how close the soil is to PWP for a particular hydrozone. The closer the soil is to the PWP, the higher the allowed sustained wind speed is.

Last edited by Kiril; 05-05-2014 at 09:27 AM.
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Old 05-05-2014, 09:48 PM
deekay1622 deekay1622 is offline
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Somewhere between 12 to 35 MPH according to Hunter.

I've seen the pattern stay pretty tight in winds of about 10 MPH (mas o menos). From there it can start to get pushed around in gusts around 20 MPH. I've never been measuring wind speed at these times, just a guesstimate by those of us observing at the time.

Mayber the Hunter TECH guy on this board has the best answer for you.

I have a simialr problem at some of my sites near the Altamont Pass (largest concentration of wind turbines in the world according to Wikipedia). It blows so hard, so often (insert joke here) that getting water down efficiently becomes an excersise in futility.

MP Rotators are a good option in high wind areas IMHO.
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