Precipitation Rates

September 06, 2010

As I write this on a rainy Labour Day morning, it occurs to me that it's a good opportunity to explain precipitation rates, one of the most fundamental aspects of irrigation design. With irrigation, we're essentially "creating" our own rain. The challenge is to do it as well as nature does, with a relatively even distribution of water across the landscape (particularly for lawns). As an experiment, if you were to put out some catch cans on your lawn while it was raining, and then measured the amount collected in each, you would see a pretty consistent amount of water collected in them (unless they were placed under an obstruction like a tree or something, of course). This is what we call a "Matched Precipitation Rate" in the industry, when every section of an area, such as a lawn or a garden bed, is getting close to the same amount of water applied to it by the irrigation system. And when areas are being evenly watered, they tend to be evenly healthy and green as well.

So when we're designing a system, the trick is to try to achieve that "Matched Precipitation Rate." This can be a challenge. It has always been very difficult using the traditional "spray" and "rotor"-style sprinklers to achieve matched precipitation rates. The primary reason for this is that, for instance, a rotor that sprays 30 feet (the radius) and puts out 1 Gallon of water Per Minute (1 GPM for short) will be putting out the same amount of water, no matter what the arc of its rotation is set for- 90, 120, 225, or 360 degrees, it will still be applying 1 GPM to that area (and the same rule applies to sprays as well).

To illustrate this problem, in the diagram below we have 3 round lawns, each measuring 60 feet across, and cut into four 90 degree quadrants. In the centre of the first one is a 1 Gallon Per Minute, 30 foot radius rotor-style sprinkler set to rotate in a 90 degree arc; in the centre of the second, a 1 GPM, 30 foot rotor set in a 180 degree arc; and in the third a 360 degree rotor with the same radius and GPM. If we then turned all the sprinklers on, we could measure and observe that the 90 degree rotor was putting down 1 GPM in its quadrant; the 180 degree rotor was putting down .5 GPM in each of its 2 quadrants; and the 360 degree rotor was only putting down .25 GPM in each of its 4 quadrants. You can imagine then, if we put these all together in one lawn, running at the same time, no matter how we arranged the sprinklers we would end up with very different precipitation rates across the lawn. It gets even worse if one area is 30 feet wide, then the lawn narrows to 24 feet, then down to 15, which is an example of a common scenario. Precipitation Rates Diagram

It also helps to understand that, traditionally, radiuses (distance) and flow rates (GPM) have been closely tied together, not leaving much room for flexibility. You couldn't just have three rotors throwing 30 feet, with one at 1 GPM, another at 2 GPM, and a third at 4 GPM (which would solve our problem very easily). It was a problem the engineers couldn't solve. So there have been 2 ways for irrigation designers to deal with this problem. The proper way was by separating all the sprinklers with different arcs into different zones of irrigation. So all the 360 degree rotors would be put on one zone together, that would operate as a group; the 180 degree rotors would have their own zone, and the 90s would have one as well. Then you would schedule the 360 degree zone to run for 4 times as long as the 90, and the 180 degree zone twice as long as the 90. That way, you would achieve a matched precipitation rate in the area.

The problem was, this could be an expensive option. Separating a sports field into different zones is one thing, but in a typical residential backyard, it can get a little pricey to have all those separate zones in one area. Which led to the second way of dealing with this problem: ignore it. Just stick all the different sprinkler arcs together on one zone, and if one area isn't getting enough water, just set the run time longer. So parts of the lawn would usually get over-watered, to compensate for the poor coverage in other parts.

Fortunately, there is a product that alleviates this problem. The Hunter MP Rotator multi-stream rotor is a marvel of engineering, designed expressly to allow sprinklers with different radiuses (up to 30 feet) and arcs to be mixed together in one zone, and still achieve Matched Precipitation (which is what the "MP" in the name stands for), just like Mother Nature! This is illustrated in the diagram below:

MP Rotator Diagram

Island Waterwise uses MP Rotators on nearly all of our installations, and also very frequently when we're making improvements to existing systems. We'd love to show you what they can do in your landscape. Just click on the "contact us" link above to send an e-mail, or call us at one of the numbers listed below. We'll be happy to come to your property and prepare a free estimate, either for installing a new system for you or making improvements to your existing system.

(To read more information on MP Rotators, follow this link, and to view a video on them, click here).

Thanks very much for visiting our website. If you have any questions about this article, or anything else related to irrigation in general, just drop me a line and I'll do my best to help.

Best regards,.

Mike Isacson, CIC, CID, CIT, CLIA, CIS (what do these letters mean? Click here to find out!)

Owner, Island Waterwise Irrigation Inc.

UPCOMING EVENTS: On September 29th, Island Waterwise owner Mike Isacson will be co-teaching the IIABC Certified Irrigation Technician (CIT) Level 1 Course at Royal Roads University, along with Karen Hounsome of Eljay Irrigation in Saanichton. Thanks to the CRD for their sponsorship of this course. For registration information, click here.

November 22-26- The Irrigation Industry Association of BC (IIABC) will be hosting its annual Convention and Trade Show at the Inn at Laurel Point in Victoria BC. For more information, click here.

Washington -- The Yankees' bullpen may have checked different on a daily basis this past time, but as Dellin Betances was able to learn at the the season, Mariano Rivera's presence and advice were still just a quick meaning away.

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Finishing third behind Bright Sox slugger Jose Abreu and Angels pitcher Matt Shoemaker to the American League Jackie Robinson Newbie of the Year Award, as decided on by the hockey Writers' Association of America, Betances said that His picked up pointers that should help him build on of which impressive campaign.

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'Mariano has always been a great mentor, even to this day,In . Betances said Monday on hockey Network. 'He's always had a beneficial outlook, and for him, the crucial element was keeping things simple. No matter what happens, you ignore that day and tomorrow is usually a new day. His ended up being always great about that.'

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The 26-year-old Betances as well as Rivera bonded first as teammates and after that in the history books, because Betances shattered Rivera's franchise single-season record intended for strikeouts by a reliever, logging 135 strikeouts in 90 innings.

Rivera set the old mark in 1996, eye-catching out 130 men throughout 107 2/3 innings as an elite setup male for John Wetteland en route to your global Series championship. With Jesse Robertson's next move uncertain, Betances continues to be mentioned as a possible future nearer, and it would be no surprise in case Rivera offered more guidance with the role.

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'The success that I received this year, I remember [Rivera] giving me a call through the bullpen coach [Gary Tuck] and telling me to slow factors down and just try to continue to be consistent,' Betances said.

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A Washington City product who still treasures their ticket stub from David Wells' Before 2000 perfect game, Betances went 5-0 using one save and a 1.40 ERA in 75 appearances overall after being named to his initial Opening Day roster.

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'It's the very best feeling ever,' Betances mentioned. 'I grew up a Yankees supporter, I went to David Wells' great game. For me to have this coming year wearing the pinstripes, it's actually a dream come true.'

Once touted to be a top starting-pitching prospect, the 6-foot-8 Betances had trouble with his control in the Modest Leagues and was demoted for you to Double-A at the end of 2012, where the Washington yankees began the process of converting your pet into a reliever.

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The adjustments became predominant this spring, as Betances delivered his way onto the team and eventually moved into the build role in front of Robertson, showcasing a fastball in the high 90s together with a nasty slurve that prompted many swings and misses. Any time Betances was ahead in the rely, opponents batted just .076 against him.

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Betances led all AL prescriptions in innings pitched, holding foes to a .149 batting normal and ringing up the many strikeouts by a rookie reliever due to the fact Mark Eichhorn of the Blue Jays fanned 166 adult men in 1986.

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'I felt like my own program that I had in the actual offseason leading into Spring Coaching helped me a lot,' Betances mentioned. '[Manager] Joe [Girardi] was big in communicating with us guys inside bullpen, just making sure everything was all right and felt wonderful. If we needed a day, His was always there to give you that.'

Washington, Fla. -- The Twins changed a slow start Sunday in addition to rallied to defeat the Marlins, 4-2, within a Grapefruit League game on Hammond Stadium.

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Minnesota fell into a young 2-0 hole, but scored the actual game's final four extends -- including two in the bottom in the seventh -- to secure the victory. With runners about second and third, a couple outs and the game deadlocked at 2, Twins shortstop Eduardo Escobar roped a line drive into left field that will scored both runners on what proved to be the game's important play. Escobar was caught in the rundown and was sooner or later tagged out between third and fourth on the play, but the damage had been done by that point.

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The game started with a battle involving two starting pitchers each going through his former team, because Twins sent Ricky Nolasco to the mound and Miami turned to Kevin Slowey, though neither factored into the decision. Each pitcher tossed five innings and departed with the game tied at A couple of.

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In his five innings, Slowey limited his former club to two operates with four hits, while eye-catching out one and jogging another. Nolasco, meanwhile, allowed a couple of runs on seven hits along with struck out three as part of his first start since being referred to as Minnesota's Opening Day starter.

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'It felt good,' Slowey said. 'It ended up being good to build off of last outing and be able to throw more breaking balls and see them working in counts against large league hitters. Having the possiblity to stretch out to five innings was excellent, too. I'll just be ready for any role, whatever that might be.'

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The Marlins jumped out to an early guide when they pieced together three direct hits to start the second inning, the last of which was an RBI bunt single by simply Reed Johnson that put New mexico ahead, 1-0. Nolasco, however, then compelled designated hitter Viosergy Rosa to soil into a double play, and secondly baseman Justin Bohn grounded out a single batter later to end the threat.

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'I thought it was good over-all,' Nolasco said. 'I didn't stroll anybody and it was good to work out of the stretch. Definitely, you don't want to work that much out of your stretch, but that's where you intend to make your most important pitches, so that it was good.'

Miami added a different run one inning later when catcher Rob Brantly reached on a fielder's selection, moved to second on a crazy pitch then scored over a Jeff Baker single to center field to force the lead to two.

The Twins responded to back in the bottom of the inning, having right fielder Oswaldo Arcia leading off with some sort of towering fly ball of which carried to the warning course in left field for a triple. His scored just one batter later on a groundout simply by catcher Kurt Suzuki.

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Two innings later, Minnesota put together an additional rally to even the ranking at 2. Veteran selected hitter Jason Kubel worked the leadoff walk from Slowey and later arrived around to score on an Arcia give up fly to center field.

The play temporarily evened the report and ultimately set up Escobar's game-winning hit as the Twins improved to 7-7-3 inside Grapefruit League play, and also the Marlins fell to 11-6-2.

Up Next: Shortstop Pedro Florimon is expected to make his Grape fruit League debut Monday, in the event the Twins head to Sarasota, Fla., to take on the Orioles in an NHL.TV transmit. Florimon has been recovering from having his appendix removed on Feb. 18. Right-hander Kevin Correia will get the start for Mn, opposite Baltimore newcomer Ubaldo Jimenez. The first frequency is scheduled for Seven:05 p.m. ET within the first of two straight nights games for the Twins.