Sufficient amounts of water must reach the soil in order to nourish plants. However, it is estimated that as much as 50% of this water is wasted due to over-watering (21). New irrigation control technologies offer simple and reliable ways to reduce such waste by fitting watering schedules to site conditions.
Weather Based Irrigation Controllers (WBIC)
WBIC are intended to trigger irrigation cycles according to local weather forecasts. The system receives information via Wi-Fi from a constantly updating weather database and is able to estimate soil moisture levels in order to determine the optimal amount of water needed; this can reduce water consumption by eliminating unnecessary automated irrigation cycles.
Research
Research conducted in Ipswich, Massachusetts examined the use of WBIC in residential and municipal settings from 2005 to 2007 (23).
Evaluation:
Results:
Moderate savings were seen in residential buildings. Saving proved to be higher for households that were already over-watering. Significant savings of approximately 0.11 m3/m2/year or 121,000 gal/acre/year were estimated for municipal athletic fields.
Evaluation:
- Residential – Comparison of outdoor water use of residences with WBIC (experimental group) to neighboring residences without the system (control group). Furthermore, a comparison was made between the experimental group’s actual water consumption prior to WBIC installation (2003-2004) to the estimated volume of water that would have been applied by the WBIC during that same period.
- Municipal – Comparison of actual water use prior to WBIC installation to simulated water use with WBIC for same time period (2003-2004), using known historic weather records, for 5 athletic fields.
Results:
Moderate savings were seen in residential buildings. Saving proved to be higher for households that were already over-watering. Significant savings of approximately 0.11 m3/m2/year or 121,000 gal/acre/year were estimated for municipal athletic fields.
On-campus Implementation
WaterSense, a partnership program by the U.S Environmental Protection Agency, has a special label for water efficient products, which include irrigation controllers. Labeled controllers are weather-sensitive, third party certified and meet EPA criteria for water conservation, promising irrigation adequacy greater than 80% and irrigation excess lower than 5% (24). A list of all labeled controllers, made by over 15 different manufacturers, can be found on epa.gov.
The University of Houston’s Master Construction Specifications for Landscape Irrigation call for Base-line’s BaseStation 3200 irrigation controllers (25). These are advanced controllers with many specifications but do not meet WaterSense criteria. Certified WBIC can be tested on the university campus, ideally on athletic fields: large, exposed areas of turf.
Drawing upon results from the aforementioned Ipswich study, we can calculate hypothetical water savings associated with the University of Houston’s athletic field irrigation. Here, we considered six athletic fields on the UH campus and use the resulting savings of
0.11 m^(3)/m^(2)/year to gauge possible savings.
The University of Houston’s Master Construction Specifications for Landscape Irrigation call for Base-line’s BaseStation 3200 irrigation controllers (25). These are advanced controllers with many specifications but do not meet WaterSense criteria. Certified WBIC can be tested on the university campus, ideally on athletic fields: large, exposed areas of turf.
Drawing upon results from the aforementioned Ipswich study, we can calculate hypothetical water savings associated with the University of Houston’s athletic field irrigation. Here, we considered six athletic fields on the UH campus and use the resulting savings of
0.11 m^(3)/m^(2)/year to gauge possible savings.
Although the annual savings 0.11 m^(3)/m^(2)/year were used from the Ipswich study, they can be adopted for our purposes. The Ipswich region receives an annual average of 46.81 inches of rain, which is comparable to Houston’s annual average of 49.77 inches of rain (27,28). Furthermore, plants demand less watering in the colder New England climate than in the warmer Texas climate, which makes it reasonable to assume that over-watering is at least as serious of a problem in Houston, if not more so.
Nevertheless, theoretical annual savings of over 2.3 million gallons of water, and nearly $10,000 in payments, per year strongly supports possible implementation of weather based irrigation control for athletic fields and other green spaces in the UH campus.
Nevertheless, theoretical annual savings of over 2.3 million gallons of water, and nearly $10,000 in payments, per year strongly supports possible implementation of weather based irrigation control for athletic fields and other green spaces in the UH campus.
Devices & Costs
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ConclusionThe city of Houston is located in a humid subtropical climate zone and receives rainfall every month of the year amounting to roughly 50 inches of rain annually (28). Implementation of weather sensitive irrigation control can lead to a significant reduction in excess watering, especially in the hot summer months when over-watering is more common.
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