Monday, July 14, 2014

Applying science to water savings: smart irrigation month 2014

In late June I had the opportunity to join Miami-Dade’s Urban Conservation Unit (U.C.U.) for a day in the field visiting properties participating in Miami-Dade County’s Irrigation Rebate Program.

Front yard turf zone, circa 2011
Playing the classics
The final visit for the day was a home in Coral Gables, the City Beautiful. In 2011, this residence had rehabilitated its potable water irrigation system and installed a weather-based irrigation controller (WBIC). With a landscape that features mostly palms, shrubs and decorative stones, a seven zone irrigation system has no business at this location. In any case, the controller installation was rebated in 2011 and the homeowner asked the team to stop by to see if things were still on the up and up.

No longer on the up and up: Jesus Lomeli and a riser nozzle gone missing
A bit about WBICs
Once we realized where we were, U.C.U. tech Jesus and I had eyes big as saucers. Why? Two words: applied science. Weather-based irrigation controllers require very specific programming for each zone:
  • soil type
  • plant type
  • shade factor
  • sprinkler head type, etc.
All those factors are churning away in this little guy right here
The WBIC model at this location uses these factors along with weather data from an on-site weather sensor/tipping bucket rain gauge to calculate evapotranspiration (or ET). This ET value is then used to generate run times for each zone. When a landscape is designed with hydrozones in mind, much like this one with one turf zone and six tree or shrub zones, a weather-based controller can really work its magic.

Weather sensor: perfectly located and busy doing science 
So after a quick zone by zone wet-check to look for breaks or other problems, we dove into the controller’s “history” feature to track the watering events by date starting from January of this year.

Smart irrigation month is an industry-fostered construct that promotes outdoor water-use efficiency during the month of July, the outdoor water-use peak in the calendar year. The Irrigation Association recommends a plethora of practices from design to technology that, if implemented, can reduce water-use while still maintaining a healthy landscape.

Tree canopy shade is real: front yard turf zone in 2014
Better living through tech
In the best of all possible worlds the property I'm discussing here would have no (or temporary) irrigation. There would be a colorful Florida-friendly groundcover in the shady front area, and all the remaining ornamental areas would continue to live off rain alone. 

Back yard rocky expanse: wait, what...
In this world, however, the weather-based controller was expertly managing water-use for this landscape – irrigating the lone turf zone regularly, and watering the other zones once a month, or once every few months. During especially rainy stretches, the system would not run for weeks. 

Some water-wise options from Ewing Irrigation
The takeaway
There is definitely room for improvement at this location - namely low-volume irrigation in the six tree/shrub zones - but the best decision this homeowner ever made for the landscape (and water bill) was installing a WBIC three years ago. This wasn't the first time Jesus and I had seen a weather-based controller save water this way, but it's the most recent, and on the cusp of smart irrigation month 2014, all the sweeter.

About the author: 
Michael Gutierrez is a water resources 
technician with UF/IFAS in the Ag & Bio 
Engineering Dept. He tweets, blogs and 
also shoots still and video media in South 
Florida, Gainesville and anywhere else a 
camera is handy. (image: Martha Golea)