Smart Irrigation Controllers Research Articles

Smart Irrigation Controllers in Residential Applications and the Potential of Integrated Water Distribution Systems

Smart Irrigation Controllers in Residential Applications and the Potential of Integrated Water Distribution Systems

Why Is Residential Irrigation So Hard to Optimize?

Irrigation of residential landscapes is one of the largest demands for municipal water suppliers. However, it is often done inefficiently and is a concern for limited capacity and low pressure. Why, really, is residential landscape irrigation so inefficient, and why is it so difficult to optimize? The problem, as we suggest framing it, comes down to four C’s: conditions, components, controls, and customers. The conditions for efficient irrigation are too complex, sprinkler components are too imprecise, sprinkler controls too simplistic, and most water customers are too untrained as irrigators. Any management system with so many weaknesses is sure to be inefficient. Better plant choices, better landscape layouts, and precision irrigation technology are obvious solutions. Beyond these solutions, we recommend further development of smart irrigation controllers that account for the complexity of irrigation conditions and allow remote control by the water supplier. For an incentive, owners can opt-in and occasionally have their irrigation delayed or skipped if the water supplier needs to shed demand. We call this an “integrated water distribution system” where one benefit is a discretionary water demand that can be coordinated between suppliers and customers.

The Conservation Potential of Smart Irrigation Controllers for Over‐Irrigators

Key TakeawaysWith water demand projected to rise substantially in Florida, strategically designed and targeted conservation programs are important for reducing overall water use.According to a Florida study, over‐irrigators could cut their monthly water bills by more than $35 by using a smart irrigation controller.Utilities stand to benefit from establishing effective conservation programs; in the case of this study, water demand could drop by 1.62 mgd if smart irrigation controller rebates are targeted to over‐irrigators.

Comparing Smart Irrigation Controllers for Turfgrass Landscapes

Recent advances in irrigation technologies have led many states to incentivize homeowners to purchase United States Environmental Protection Agency WaterSense-labeled, smart irrigation controllers. However, previous research of smart controllers has shown that their use may still result in excess water application when compared with controllers manually programmed to replace actual water loss. This study compared kentucky bluegrass (Poa pratensis) irrigation applications using three smart irrigation controllers, a conventional irrigation controller programmed according to Cooperative Extension recommendations, and the average irrigation rate of area homeowners in Utah during 2018 and 2019. Of all the controllers tested, the manually programmed controller applied water at amounts closest to the actual evapotranspiration rates; however, smart controllers applied from 30% to 63% less water than area homeowners, depending on the controller and year of the study. Kentucky bluegrass health and quality indicators—percent green cover and normalized difference vegetation indices—varied between years of the study and were lower than acceptable levels on several occasions in 2019 for three of the four controllers tested. Compared with the results of similar studies, these findings suggest that the effects of smart irrigation controllers on turfgrass health and quality may vary by location and over time.

Long‐term performance of smart irrigation controllers on single‐family homes with excess irrigation

Long‐term performance of smart irrigation controllers on single‐family homes with excess irrigation

Selecting High-Impact Landscape Irrigation Conservation Behaviors: Formative Research to Inform Behavior-Change Efforts

Background This work addresses the increasing prevalence of water scarcity. Droughts are projected to worsen as a result of climate change and urbanization, increasing the need for all sectors to reduce the amount of water used. Home landscape irrigation represents an important opportunity to reduce water use in the United States. Focus of the Article This formative research study used social marketing techniques to estimate potential impact of irrigation water conservation behaviors, weight and prioritize the behaviors to guide behavior selection in the context of residential irrigation conservation. Research Objective The objectives were to estimate (1) the potential impact of, (2) current adoption levels and likelihood of adoption of, and to (3) prioritize various landscape irrigation water conservation behaviors. Program Design/Approach When addressing any issue, including water scarcity, identifying target behaviors is the first, foundational step for a successful social marketing campaign. This research focuses on formative social marketing research to inform local interventions designed to reduce the amount of water applied to residential yards across the United States. Importance to the Social Marketing Field This study outlines a process to compare and prioritize water conservation behaviors with the goal of reducing residential landscape irrigation usage. We demonstrate a technique for obtaining this type of formative research, the lack of which can serve as a barrier to change agents promoting behaviors in any context. Methods We employed a two-pronged quantitative survey research approach to collect technical experts’ impact ranking and U.S. residents’ current adoption levels and likelihood of adopting potential irrigation water conservation behaviors. The 14-member expert panel was selected using purposive and snowball sampling techniques, and the residential sample ( N = 2601) was recruited using purposive sampling. Results Mean weights ranged from −46.55 to 61.13. Singly considering impact, current adoption levels, or likelihood of adoption would result in a different behavior receiving priority for a campaign (eliminating irrigated areas in landscapes, installing smart irrigation controllers, and following local watering restrictions, respectively). However, when these values were considered together, installing drought-tolerant plants in the yard had the greatest overall weight. Limitations A possible conceptual limitation of this case study was the national scope of our research. The findings provide valuable baseline data for behavior change practitioners working across the country, and it is advisable to replicate this process at a local scale corresponding to the targeted intervention. Recommendations for Research or Practice The findings underscore the importance of including technical experts and target audience members early in social marketing program planning and reveal the importance of systematically approaching behavior change selection to thoroughly consider different components of potential behaviors. Behavior change practitioners working on water issues can use the weights reported here to prioritize behaviors for targeted interventions, and those working in all areas can follow the process to prioritize behaviors at the local level. There are exciting opportunities to decompose likelihood into behavioral antecedents for both research and application.

Hybrid Bermudagrass and Tall Fescue Turfgrass Irrigation in Central California: I. Assessment of Visual Quality, Soil Moisture and Performance of an ET-Based Smart Controller

Research-based information regarding the accuracy and reliability of smart irrigation controllers for autonomous landscape irrigation water conservation is limited in central California. A two-year irrigation research trial (2018–2019) was conducted in Parlier, California, to study the response of hybrid bermudagrass and tall fescue to varying irrigation scenarios (irrigation levels and irrigation frequency) autonomously applied using a Weathermatic ET-based smart controller. The response of turfgrass species to the irrigation treatments was visually assessed and rated. In addition, turfgrass water response functions (TWRFs) were developed to estimate the impact of irrigation scenarios on the turfgrass species based on long-term mean reference evapotranspiration (ETo) data. The Weathermatic controller overestimated ETo between 5% and 7% in 2018 and between 5% and 8% in 2019 compared with California Irrigation Management Information System values. The controller closely followed programmed watering-days restrictions across treatments in 2018 and 2019 and adjusted the watering-days based on ETo demand when no restriction was applied. The low half distribution uniformity and precipitation rate of the irrigation system were 0.78 and 28 mm h−1, respectively. The catch-cans method substantially underestimated the precipitation rate of the irrigation system and caused over-irrigation by the smart controller. No water-saving and turfgrass quality improvement was observed owing to restricting irrigation frequency (watering days). For the hybrid bermudagrass, the visual rating (VR) for 101% ETo treatment stayed above the minimum acceptable value of six during the trial. For tall fescue, the 108% ETo level with 3 d wk−1 frequency kept the VR values in the acceptable range in 2018 except for a short period in mid-trial. The TWRF provided a good fit to experimental data with r values of 0.79 and 0.75 for tall fescue and hybrid bermudagrass, respectively. The estimated VR values by TWRF suggested 70–80% ETo as the minimum irrigation application to maintain the acceptable hybrid bermudagrass quality in central California during the high water demand months (i.e., May to August) based on long-term mean ETo data. The TWRF estimations suggest that 100% ETo would be sufficient to maintain the tall fescue quality for only 55 days. This might be an overestimation impacted by the relatively small tall fescue VR data in 2019 owing to minimal fertilizer applications and should be further investigated in the future.

Long‐term performance of smart irrigation controllers on single‐family homes with excess irrigation

AbstractThe main objective of this study was to evaluate the long‐term water conservation potential of two smart irrigation controllers when implemented in single‐family homes with excess irrigation. Treatments were established in Orange County, Florida, across two types of soils and included homes monitored only (MO), homes that received an evapotranspiration (ET) controller or a soil moisture sensor (SMS) controller, and homes that received an ET or SMS plus an onsite specific programing and tutorial given to the homeowner (ETPgm or SMSPgm, respectively). All treatments resulted in significant water savings compared with the MO group, without negatively affecting the turf quality. Average irrigation reductions in sandy and flatwoods soils for ET were 21% and 17% and 26% and 31%, respectively, in the ETPgm group. The SMS group reduced irrigation by 18% and 42% in flatwoods and sandy soils, respectively, while the SMSPgm treatment applied 41% and 35% less water, respectively.Article Impact StatementWater entities and utilities planning to create a rebate program using smart irrigation controllers can benefit from this long‐term study.

AWWA Water Science Author Spotlight

Having recently published an article in AWWA Water Science, Maria Morera answered a few questions from its editor-in-chief Kenneth L. Mercer about the research. Evolving Response to Smart Irrigation Controllers in High Water-Use Central Florida Homes Maria C. Morera, Paul F. Monaghan, Michael D. Dukes Maria enjoying a stroll through San Juan, Puerto Rico, after attending a conference. Photo courtesy of Alicia Peón Arceo. I'm part of a collaborative research team that is currently examining environmental attitudes, water savviness, yard care practices, and the demographics associated with receptivity to stormwater best management practices. We are preparing to collect data through an electronic survey of several thousand homeowners in a southwest Florida master-planned community. We expect that the quality of homeowners’ experiences with their neighborhood stormwater ponds will affect their preferences. Powerful scientific ideas transcend disciplinary boundaries, so being open-minded and feeling comfortable working in groups of scientists with diverse backgrounds and different areas of expertise are strengths I draw on as a researcher. The research behind our recent article in AWWA Water Science was the culmination of five years of longitudinal work that began as an external evaluation of a pilot project designed to test smart irrigation controllers under residential conditions. We were very interested in identifying the factors that influence homeowners’ long-term adoption of the water-saving technologies. We knew the controllers performed well in terms of irrigation adequacy and scheduling efficiency, yet over time we found homeowners’ experiences and familiarity with the devices ultimately determined their continued use. A key takeaway was the importance of well-tailored informational strategies for effective promotion of conservation behaviors among high irrigators. Maria collaborating on the development of an electronic survey in Gainesville, Florida. Photo courtesy of Maria Morera I grew up near the Everglades. Our school field trips immersed us in the ecology of South Florida. We had learning activities that included snorkeling over a coral reef, wading through a cypress dome, and camping in the pinelands. At the time, I was just having fun, but those excursions instilled in me a deep appreciation for sound natural resource management. To learn more about Maria's research, see the full article in AWWA Water Science, available online at https://doi.org/10.1002/aws2.1111.

Irrigation scheduling technologies reduce water use and maintain turfgrass quality

AbstractSmart irrigation controllers have demonstrated potential for turfgrass water conservation in humid and temperate environments but have not been comprehensively tested in arid environments. The objective of this study was to determine the accuracy of a wireless capacitance sensor over a wide soil moisture range and to ascertain if smart irrigation controllers resulted in water savings without reducing quality of tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] and bermudagrass (Cynodon dactylon L.). A two‐yr study was conducted to compare turfgrass quality, root morphology, and water use of plots irrigated with a constant run time to plots for which irrigation was scheduled using soil moisture sensors (SMS), evapotranspiration (ET) [Climate Logic (CL)] controllers, or 80% of historic ET (ET80) for tall fescue and 60% (ET60) for bermudagrass. Sensors accurately tracked soil moisture up to salinity levels of 4 dS m−1. Turf performance and root morphology were not affected by irrigation treatments for either grass. Compared to tall fescue plots irrigated with constant run time, plots irrigated using ET80 and CL required 38% less water, and SMS plots used 44% less than tall fescue. Scheduling bermudagrass irrigation by ET60, CL, and SMS resulted in a 29, 42, and 39% reduction in water applied compared to constant run time. The majority of water savings was in spring and fall. Water requirement for bermudagrass during the summer did not differ between the scheduling treatments. Our study confirms that smart irrigation controllers can be used as an effective measure to conserve water in an arid environment.

Irrigation Savings from Smart Irrigation Technologies and a Smartphone App on Turfgrass

HighlightsAll tested smart irrigation technologies regulated irrigation based on real-time soil moisture and weather conditions.Treatments based on SMS, ET, or smartphone app applied less water than the comparison treatment by 51% to 63%, 28% to 66%, and 51% to 63%, respectively.The payback period for the different technologies ranged between 0 and 12 months.Abstract. A plot study comparing a variety of irrigation scheduling technologies was conducted in Gainesville, Florida, from 2015 to 2017. Our study objectives were to: (1) compare the ability of different irrigation scheduling technologies to bypass scheduled irrigation cycles and/or decrease water application; and (2) compare water savings. Twelve irrigation scheduling treatments were investigated, with each replicated three or four times. Treatments included time-based schedules without sensor feedback (WOS), with a rain sensor, deficit irrigation with a rain sensor, and non-irrigated. Also included were three soil moisture sensor (SMS) based treatments, three weather or ET-based treatments (ET), and two smartphone app-based treatments. Significant differences in turfgrass quality among all treatments (including non-irrigated) were not observed during the testing periods, which tended to be wetter than normal. Compared to WOS, the SMS, ET, and smartphone app treatments achieved water savings of 51% to 63%, 28% to 66%, and 51% to 63%, respectively, depending on treatment specifics. Inclusion of additional practices, such as a split irrigation strategy (half in the morning and half in the evening) and seasonal deficit irrigation, were shown to be advantageous in an area where rainfall is frequent and a substantial contributor to plant water needs. The SMS treatments saved water by bypassing scheduled irrigation cycles, the ET controllers saved water mainly through lower application depths, while the app-based treatments saved water through a combination of bypassing and applying lower irrigation depths. The payback period for the evaluated scheduling technologies ranged between 0 and 12 months. Financial and practical considerations should be included when recommending or acquiring one of these irrigation scheduling technologies. Keywords: Evapotranspiration controllers, Smart irrigation controllers, Smartphone apps, Soil moisture sensors.

Two Decades of Smart Irrigation Controllers in U.S. Landscape Irrigation

HighlightsSavings numbers in new studies across multiple soil types and climates are similar to those summarized in 2011 and are summarized here as 51% in research plot studies and 30% in single-family homes.Studies of the human factors have begun showing how important the users are to success of the technology.Education in implementation remains important to achieve potential water conservation.Abstract. Smart irrigation controllers, such as evapotranspiration (ET) and soil moisture sensor (SMS) controllers, have become commonly available from virtually all irrigation controller manufacturers. This review summarizes the literature since the Fifth Decennial National Irrigation Symposium (NIS) concerning these controllers in research studies and pilot implementations. Studies have expanded to multiple climates throughout the U.S. on a variety of soils and plant types. When these devices are implemented properly on sites that have potential irrigation savings (i.e., excess irrigation), they are able to reduce irrigation while maintaining plant quality. The level of reduction depends on many factors, including the amount of excess irrigation, climate, plant type, and human interaction with the technology. When studies report positive savings, the levels documented here range from 40% to 61% (51% avg.) in plot studies and from 28% to 32% (30% avg.) in residential studies. Of 17 identified studies in the past decade, five reported negative savings, and in most cases those results were due to ET controllers installed on sites with little excess irrigation or controller programming that was not optimized for savings. New trends in the industry include Wi-Fi signal-based ET controllers with smartphone app capability, an upcoming standard for SMS controllers, as well as smart controllers becoming mandatory in areas of the U.S. As identified in the Fifth Decennial NIS, it remains important to implement controllers on sites with the potential for irrigation reduction as well as proper implementation with the best current information. Finally, there is a need to understand human interaction with these devices because improper programming can make the difference between a water-saving device and ineffective technology with a dissatisfied customer. Keywords: ET controller, Landscape irrigation, Smart controller, SMS, Soil moisture sensor, Soil water sensor.

A Hybrid Method for Smart Irrigation System

Internet of Things (IoT) is a boon to the technological developments during the past decade. Though the adoption of this technology in agriculture has gone up immensely in recent years, the implementation of the smart irrigation system remains its initial stage in this agricultural setup. The sprinkler or dripper irrigation methods are widely used in the smart irrigation environment. In this paper a hybrid method is proposed to select the irrigation method automatically based on the climate changes and soil moisture level. By enhancing this method using the rapid growing technologies and IoT enabled smart irrigation controllers, the agriculture sector will be improved over the foreseeable future.

Investigating Homeowners’ Preferences for Smart Irrigation Technology Features

Smart irrigation systems are relatively new technologies that optimize irrigation schedules in residential landscapes, thus leading to reduced irrigation water use and potential contamination. To promote the use of such technologies, the landscape services industry has introduced innovative features such as the integration of local weather data into irrigation controller systems or mobile phone control and alert notifications that help to facilitate usability and prevent over-irrigation. Very few studies have addressed homeowners’ preferences for outdoor irrigation technologies. This study investigates homeowners’ preferences for smart irrigation systems for residential landscapes. We utilized online survey data to examine how homeowners’ knowledge and perceptions influence their preferences for specific features such as automatic failure alert and notifications, mobile control, integration with weather-based and soil-moisture sensor-based irrigation, home automation, and touchscreen displays. Results estimated by the rank-ordered logit model revealed that knowledge and perceptions of smart irrigation controllers are significantly correlated with homeowners’ preferences for water efficiency features. The results offer practical implications for policymakers and the residential irrigation industry as they develop and promote smart irrigation technologies to conserve water resources.

Towards sustainable water management: Preferences and willingness to pay for smart landscape irrigation technologies

Urbanization trends, leading to growing irrigated residential landscapes continue to escalate concerns on surface, ground, and drinking water quantity and quality among environmental groups and regulatory agencies. While automated lawn irrigation systems established in urban areas are critical factors affecting water quantity and quality, homeowners’ water use may vary with their preferences for lawn irrigation systems. The choice of an irrigation system is not determined only by local restrictions or policies but also by homeowners’ preferences. Further, individuals’ preferences can be influenced by the availability of product-specific attributes such as evapotranspiration or soil-moisture based controllers (known as smart irrigation controllers). With a focus on single-family home residents in California, Florida, and Texas, the present study uses the discrete choice analysis framework to link smart irrigation attributes (e.g., sensor types, wireless operation, remote control, alert notification) and monetary incentives (e.g., annual water bill savings, rebates) to preferences and willingness-to-pay. Results indicate that homeowners prefer smart irrigation controllers to conventional automated systems, and that savings on annual water bills could be one of the most important features determining adoption of smart irrigation controllers. Controller features such as the type of operation (i.e., wireless/on-site weather station) and system malfunction alert/notification also impacted homeowners’ preferences. The findings provide practical insights into the promotion of smart irrigation controllers that can be integrated with educational campaigns, or advertisements highlighting benefits of smart irrigation technologies. Clearer understanding about homeowners’ preferences could serve as a feedback loop for policy makers and improve water policies at state and local levels.

Evolving response to smart irrigation controllers in high water‐use central Florida homes

Efforts to improve urban irrigation efficiency through the promotion of smart controllers represent a critical water resource management strategy in Florida. However, targeted initiatives require knowledge of household characteristics and preferences among high irrigators to ensure acceptance and continued use of the devices. This article compares survey data collected in 2014 and 2017 from high‐water‐use homes in Orange County, Florida, with soil moisture sensor and evapotranspiration controllers installed, to evaluate long‐term response to the technologies. Results indicate the perceived water‐saving effectiveness of the controllers and whether challenges were experienced operating them significantly predicted satisfaction with the controllers and the likelihood of continuing to use them, respectively, during both periods. The likelihood of continued use after 2017 was almost 12 times higher if a respondent was satisfied with the controller and 82% lower if any challenge was experienced with it. Increased familiarity and comfort with the controllers would enhance long‐term adoption.

Predicting Satisfaction with Smart Irrigation Controllers and Their Long‐Term Use among Homeowners in Central Florida

AbstractStudies throughout Florida have shown smart controllers can substantially reduce irrigation under residential high‐water use conditions. However, successful promotion requires understanding the link between controller performance and the mechanisms by which they are adopted. This article compares irrigation water‐use and survey data collected from households installed with soil moisture sensor and evapotranspiration controllers. The study investigated whether the relative change in irrigation use between two years preceding and two years following installation was a reliable predictor of a homeowner's satisfaction with the device and likelihood of continuing to use it. Results indicated relative changes in irrigation use were only significantly associated with the quality of controller programming. Satisfaction with the controller was largely attributable to satisfaction with the appearance of the landscape and the perceived water‐saving effectiveness of the controller whereas the likelihood of its continued use was only significantly predicted by the level of technical knowledge regarding its functioning and whether or not challenges were experienced with it. Targeting homeowners with supplemental user‐friendly information may best support their long‐term adoption of smart controllers while providing irrigation contractors with training in implementation techniques would represent an integrated strategy for added reductions in residential outdoor water use.

Relating Knowledge and Perceptions of Sustainable Water Management to Preferences for Smart Irrigation Technology

Water quantity and quality concerns in urban environments have prompted conservation groups, governmental agencies, and policy makers to develop and promote residential water conservation programs, including restrictions on residential landscape irrigation practices and incentives for the adoption of water-efficient appliances. Previous literature links household characteristics, financial incentives, and demographic characteristics to the adoption of water-efficient appliances and overall water use. However, relatively little attention has been given toward understanding how homeowners’ perceptions and knowledge of smart irrigation technologies affect their preferences or stated purchase likelihood of such irrigation equipment. To address this gap in the literature, this paper identifies perception- and knowledge-related factors that are correlated with the purchase likelihood of smart irrigation controllers. The generalized logit regression model results suggest that knowledge about irrigation systems and residential landscaping are positively correlated with purchase likelihood. Similarly, homeowners’ perceptions about conservation efforts, water restrictions, and their neighbors’ irrigation habits all increase purchase likelihood. Combined with statistically-significant correlations of several socio-demographic variables and purchase likelihood, these results have theoretical and practical implications, which are summarized in this paper.

Evaluating two irrigation controllers under subsurface drip irrigated tomato crop

Smart systems could be used to improve irrigation scheduling and save water under Saudi Arabia’s present water crisis scenario. This study investigated two types of evapotranspiration-based smart irrigation controllers, SmartLine and Hunter Pro-C2, as promising tools for scheduling irrigation and quantifying plants’ water requirements to achieve water savings. The effectiveness of these technologies in reducing the amount of irrigation water was compared with the conventional irrigation scheduling method as a control treatment. The two smart irrigation sensors were used for subsurface irrigation of a tomato crop (cv. Nema) in an arid region. The results showed that the smart controllers significantly reduced the amount of applied water and increased the crop yield. In general, the Hunter Pro-C2 system saved the highest amount of water and produced the highest crop yield, resulting in the highest water irrigation efficiency compared with the SmartLine controller and the traditional irrigation schedule. It can be concluded that the application of advanced scheduling irrigation techniques such as the Hunter controller under arid conditions can realise economic benefits by saving large amounts of irrigation water.

An Assessment of Oklahoma City Commercial Businesses’ Willingness to Adopt Irrigation Water Conservation Methods

Outdoor irrigation water conservation in the commercial sector has rarely been studied. Periodic drought stress in Oklahoma has forced utilities departments, including the City of Oklahoma City, to seek ways of conserving water in both the residential and nonresidential sectors. Most of these efforts largely targeted the residential sector. In this study, we determined the willingness of commercial businesses in the Oklahoma City metro area to participate in water conservation methods, such as installing soil moisture sensors (SMCs), installing smart irrigation controllers (SICs) for their businesses, and participating in voluntary landscape irrigation assessments (LIA). We conducted a mail survey of 3000 commercial customers in which we used contingent valuation (CV) questions to elicit the financial savings that would induce participation in an LIA or adoption of SIC [n = 381 (13.7% response)]. A subsample experimental group received detailed information about future block rate water increases. Results of the study indicate that at current water utilities rates, commercial businesses are unlikely to adopt these conservation methods, but including information about future rate hikes may induce a subset of individuals to participate.