Accuracy of Reference Evapotranspiration Estimation by Two Irrigation Controllers in a Humid Climate
Publication: Journal of Irrigation and Drainage Engineering
Volume 140, Issue 6
Abstract
Increasing municipal water demand has led to new innovations in water-saving technology. Evapotranspiration-based irrigation controllers, also known as weather-based irrigation controllers, are a technology that use evapotranspiration (ET) estimates to schedule irrigation. Although real-time on-site data collection could help improve data quality, limited data parameters collected or simplified reference evapotranspiration () estimation methods from an on-site sensor could potentially have an impact on estimated values for stand-alone controllers. Conversely, collection of data from off-site weather stations that are not representative of the local conditions could lead to inaccurate estimations for local irrigation sites. The Weathermatic SL1600 and Toro Intelli-sense controllers were selected for testing because of the different methods of data collection and estimation. This study was conducted in two locations: Wimauma and Gainesville, Florida. In Wimauma the Weathermatic controller significantly overestimated compared to on-site estimates using the ASCE-EWRI standardized method () by 9–15% for the duration of the study, while sent to the Toro controllers was similar to on-site estimations (1–3%) for the duration of the study. However, the Weathermatic controller overestimated for every season (fall: 5–8%; winter: 6–8%; spring: 11–16%; summer: 22–25%), and the Toro controller overestimated in the summer seasons (12%) and underestimated in the winter seasons (17%). In Gainesville, the Weathermatic and Toro controllers both overestimated compared to on-site (30 and 10%, respectively). However, when compared to using data from the Gainesville National Oceanic and Atmospheric Administration (NOAA) weather station, the of the Toro controller was consistent with the equation and location of the weather data that were likely used by the weather service to calculate , indicating that this was likely the data source for the sent to the Toro controller. Overall, sent to and used by the Toro Intelli-sense controllers was closer to on-site estimations than that which was estimated by the Weathermatic SL1600 controllers on site.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The authors thank the support staff of the Agricultural and Biological Engineering Department and the Gulf Coast Research and Education Center for assistance in this research.
References
American Society of Civil Engineers-Environmental, and Water Resources Institute (ASCE-EWRI). (2005). “The ASCE standardized reference evapotranspiration equation.” ASCE-EWRI, Reston, VA.
Carrow, R. N. (2006). “Can we maintain turf to customers’ satisfaction with less water?” Agric. Water Manage., 80(1–3), 117–131.
Davis, S. L., Dukes, M. D., and Miller, G. L. (2009). “Landscape irrigation by evapotranspiration-based irrigation controllers under dry conditions in southwest Florida.” Agric. Water Manage., 96(12), 1828–1836.
Dukes, M. D. (2012). “Water conservation potential of landscape irrigation smart controllers.” Trans. ASABE, 55(2), 563–569.
Grabow, G. L., Ghali, I. E., Huffman, R. L., Miller, G. L., Bowman, D., and Vasanth, A. (2013). “Water application efficiency and adequacy of ET-based and soil moisture-based irrigation controllers for turfgrass irrigation.” J. Irrig. Drain. Eng., 113–123.
Hargreaves, G. H., and Samani, Z. A. (1985). “Reference crop evapotranspiration from temperature.” Appl. Eng. Agric., 1(2), 96–99.
Hydropoint. (2003). “WeatherTRAK ET everywhere data service technical overview.” Hydropoint Data Systems, Petaluma, CA.
Jensen, M. E., Burman, R. D., and Allen, R. G. (1990). “Evapotranspiration and irrigation water requirements.”, ASCE, New York.
Mayer, P. W., et al. (1999). Residential end uses of water, American Water Works Association Research Foundation, Denver, CO.
Shedd, M. L. (2008). “Irrigation of St. Augustine grass with soil moisture sensor and evapotranspiration controllers.” M.S. thesis, Univ. of Florida, Gainesville, FL.
Trajkovic, S. (2007). “Hargreaves versus Penman-Monteith under humid conditions.” J. Irrig. Drain. Eng., 38–42.
U.S. Bureau of Reclamation (USBR). (2007). Weather and soil moisture based landscape irrigation scheduling devices: Technical review report, 2nd Ed., Denver, CO.
Weathermatic. (2009). “Technical specifications: Smartline SL1600 series controllers.” Garland, TX, 〈http://www.weathermatic.com/sites/default/files/Technical%20Specs%20-%20SL1600.pdf〉.
Information & Authors
Information
Published In
Copyright
© 2014 American Society of Civil Engineers.
History
Received: Aug 16, 2013
Accepted: Dec 26, 2013
Published online: Feb 20, 2014
Published in print: Jun 1, 2014
Discussion open until: Jul 20, 2014
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.