Landscape Irrigation Research Articles

Designing constructed wetlands for reclamation of pretreated wastewater and stormwater

Wastewater reclamation is getting greater attention as an alternative to conventional approaches to wastewater treatment and water supply due to increasing water stress coupled with more stringent water quality limitation for discharge of treated wastewater. Among the few technologies adopted in the field for wastewater reclamation, constructed wetlands have been used to reclaim both primary and secondary treated wastewater in regions with arid and humid climates. This paper summarizes the widely adopted guidelines that need to be considered when designing constructed wetlands for wastewater reclamation, discusses the capacity of wetland treatment systems for water reuse while assessing the status of full-scale constructed wetlands designed for wastewater reclamation, and develops contaminant loading charts as a design tool based on the performance of existing full-scale constructed wetlands deployed for wastewater reclamation. It is evident that constructed wetland systems provide a viable means to treat wastewater to the levels required for low-quality reuses such as restricted irrigation and impoundment. It is challenging for constructed wetlands to consistently meet microbiological guidelines for high-quality reuses such as unrestricted agricultural and urban reuses. Wastewater reclaimed through constructed wetlands is used mainly for agricultural and landscape irrigation, groundwater recharge, indirect potable reuse, and environmental reuse. Surface area and hydraulic loading rate of constructed wetlands to be deployed for wastewater reclamation can be estimated with contaminant loading charts derived from monitoring data of existing full-scale operations.

Evaluation of relevant sprayer parameters for use with precision irrigation in landscape

The purpose of this work was to evaluate the capacity of existing landscape irrigation equipment to deliver the expected irrigation depth at a level of uniformity that can potentially be used in a precision irrigation management environment. Popular pop-up sprayer systems from two leading manufacturers (Rain-bird and Hunter variable arc and fixed arc nozzles) were subject to spatial distribution tests, in order to establish the application patterns under ideal conditions. The results indicate that it is not possible to fully rely on the catalog application depth values, with some variable arc nozzles applying up to 200% of the catalog values. These nozzles can have low values of uniformity, with Christiansen´s uniformity coefficient, CU, of between 0.31 and 0.70, making it difficult to obtain good uniformity even under a back-to-back setting. These results indicate that variable arc nozzles are not recommended for use in precision agriculture. It is preferable to use fixed arc nozzles, after actual field evaluation.

Human health trade-offs in the disinfection of wastewater for landscape irrigation: microplasma ozonation vs. chlorination

Microplasma ozonation provided more human health protection than chlorination for irrigational water reuse disinfection.

Extension Participants and Nonparticipants Differ in Water Conservation Normative Beliefs, Intentions, and Behaviors

Uncertain future availability of water is one of the most critical current issues, and outdoor water use contributes substantially to the strain on water resources. Much of the nation’s outdoor water use is through urban landscape irrigation, and one solution for conservation of this limited resource is to change home landscape irrigation practices. Thus, households that use landscape irrigation are an important audience for Florida extension programs. Complex, statewide water conservation programs are difficult to evaluate because of program variability and limited resources, yet evaluation is an important task that reveals the success, or failure, of a program. This study compared factors between people who have or have not engaged in Florida extension programs. The targeting outcomes of programs model and theory of planned behavior were used as a basis for measuring different levels of possible outcomes. There were no differences in attitudes toward good irrigation practices and perceived ability to adopt them between extension participants and nonparticipants. There were differences between the two groups in perceived normative attitudes, intent to adopt good irrigation practices, and actual engagement in landscape water conservation practices. Findings demonstrate a relationship exists between these characteristics and engagement with extension. The greatest differences were stronger social norms and more engagement in complex conservation behaviors among people who had attended extension programs. It is not known how much externalities play a role in leading certain people to seek out extension education. Extension professionals should use the findings of this study to target nonparticipants and deliver more impactful programs.

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.

Removal of Organic Compounds Using Improved Wetland Systems for Wastewater Reuse As an Example of Local Sustainable Water Management

<p class="emsd-body"><span lang="EN-GB">This paper discusses the efficiency of the removal of organic compounds using Improved Wetland System (IWS). IWS is used in Poland and enables reuse of treated effluent in landscape irrigation and toilet flushing. The first section of this paper discusses the advisability of removing organic compounds at the highest level. Additionally, the first section discusses the increase in frequency of treated wastewater reuse. So far, reuse of treated wastewater in local wastewater treatment systems included treatment and reuse of graywater only. The second section of this paper presents the average concentrations of organic compounds in domestic wastewater and the relationship existing between concentration of organic compounds in raw wastewater and water consumption. The second section discusses requirements for local (to 2000 population equivalent) wastewater treatment systems relating to reduction of organic compounds. The third section presents the current situation in rural areas in Poland and indicates the necessity of treated wastewater reuse mainly in these places. In Poland 43 % of the overall population occupies rural areas and about 70 % of them are not connected to a wastewater network. Implementation of water reuse technology (mainly IWS) is the easiest and the cheapest in rural areas. The fourth section presents the principle and the construction of the Improved Wetland System with water reuse. This part shows defects of Constructed Wetlands hindering reuse of treated wastewater. Additionally, this section discusses different steps and efficiency of wastewater treatment. The fifth section discusses results of removing organic compounds depending on hydraulic and contaminant loads. In addition, this section presents guidance on designing the IWS with technology that enables water reuse for flushing toilets and landscape irrigation. The last part of this paper discusses the summary and economic aspects of IWS used in Poland. In addition, the last part shows existing IWS </span><span lang="EN-GB">objects in Poland which provides water reuse to flushing toilets, landscape irrigation and for retention and recreational uses.</span></p>

Public health and water quality management in low-exposure stormwater schemes: A critical review of regulatory frameworks and path forward

An international review of stormwater regulation and practices, especially for low-exposure, landscape irrigation schemes in urban environments, was undertaken with a view to identifying what could be used in Alberta, Canada. A general lack of clear guidance and regulation to manage stormwater quality and potential public health risks was identified, which could be hindering the uptake of stormwater schemes generally. Particular data gaps and weaknesses identified include nominal and event performance of treatment barriers for the main acute hazards, enteric viruses and protozoa, which impacts on the ability to quantify risks and appropriately manage stormwater uses. Building on an interest to utilize stormwater for water-sensitive urban design and the Australian risk-management approach for water reuse, further guidance for the development of a risk-based regulatory approach to stormwater schemes is proposed. Using the principles of Water Safety Plans we propose a performance-based validation approach, involving the development of site-specific stormwater use management plans (SUMPs) that integrate monitoring and auditing protocols.

Population biomonitoring for the exposure to organochlorine pesticides in Thessaly, Greece

The objective of the present study is to assess wastewater effluent quality in Thessaly region, Greece, in relation to its physicochemical and microbiological burden as well as its toxic potential on a number of organisms. Wastewater may be used for agricultural as well as for landscape irrigation purposes; therefore, its toxicity potential is quite important. Thessaly region has been chosen since this region suffers from a distinct water shortage in summer period necessitating alternative water resources. During our research, treated effluents from four wastewater treatment plants operating in the region (Larissa, Volos, Karditsa, and Tirnavos) were tested for specific physicochemical and microbiological parameters [biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids (TSS), pH, electrical conductivity, selected metals presence (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn, As), and fecal coliforms’ (FC) number]. The effluents were also tested for their toxicity using two different bioassays (Daphnia magna immobilization test and Phytotoxkit microbiotest). The findings were compared to relative regulations and guidelines regarding wastewater reuse for irrigation. The results overall show that secondary effluents in Thessaly region are generally acceptable for reuse for irrigation purposes according to limits set by legislation, if effective advanced treatment methods are applied prior to reuse. However, their potential toxicity should be closely monitored, since it was found that it may vary significantly in relation to season and location, when indicator plant and zooplankton organisms are used.

Growth and Water Use During Establishment of Irrigated Bare Root and Balled-Burlap Green Ash Transplanted Into A High Desert Landscape

We investigated growth, water relations, and water use of bare root (BR) and balled-burlapped (BB) Patmore green ash following transplanting into an irrigated landscape setting in a high desert climate. Treatments were green ash harvested as larger (40 mm caliper) BB and BR trees, and smaller BR stock (25 mm caliper). During establishment, we measured canopy growth for 3 years, and for 2 years plant water relations [predawn water potential and midday stomatal conductance (gS)] and water depletion within the root zone. All treatments expressed varying degrees of isohydric responses to root loss by reducing gS that maintained water potential nearly constant, but least so for the smaller BR trees. gS was greater than that of all larger trees, meaning that for the same cost in water potential as the larger trees, BR-Small benefitted from more open stomates and presumably greater carbon gain. Greater initial conductance apparently translated into more growth. Year 1, BR-Small trees had the least total leaf area, but by Year 3 total leaf area was not different among all treatments. Also during Year 1, the ratio of water use to local reference evapotranspiration [plant factor (PF)] was 0.36 for large BR trees vs. 0.56 for BB trees, similar to the recommended PF of 0.5 for trees in dry climates. These results suggest smaller BR trees are a cheaper alternative for high desert landscapes while reaching nearly equivalent growth to BB trees after 3 years. Achieving high growth of BR trees would need careful scheduling of irrigation amount and frequency based on leaf area, root zone size, and local reference evapotranspiration.

Simplified Landscape Irrigation Demand Estimation: SLIDE Rules

Irrigated urban landscapes must increasingly maintain economic and ecosystem value with less water in response to drought amplified and shifted by climate change. Efficient landscape water management requires estimating water amount demanded by plants that can be replaced by irrigation to meet minimum performance expectations. The extant approach to estimating landscape water demand is conceptually muddled and often regionally inappropriate. Simplified Landscape Irrigation Demand Estimation (SLIDE) Rules distills scientifically credible assumptions about urban landscape biological and physical complexity into guidelines for estimating water demand that are conceptually accessible and operationally useful. SLIDE Rules are: 1) oasis urban reference evapotranspiration (ETo) effectively represents water use of urban turf seasonally and for day-to-day irrigation scheduling, but is less accurate for estimating water use of non-turf surfaces, especially in dry climates; 2) a discrete number of Plant Factors (PF) adjust ETo to estimate water demand of general landscape plant type categories—turf, non-turf, and desert—that are adjusted for temperature and drought responses; 3) a hydrozone controlled by one irrigation valve is the smallest landscape unit manageable for water, thus overall zone irrigation is governed by the highest water demand plant within that hydrozone; 4) for hydrozones

Engaging High Water Users in Water Conservation #2: High Water Users’ Water-Related Behaviors and Willingness to Act

Approximately 50% of Floridians’ daily water consumption is used for outdoor purposes, such as landscape irrigation; this is 20% higher than the national average. In order to alleviate the pressure on the precious water resources in Florida from various demands, increased public awareness and engagement in water conservation is needed especially among high water users. This 4-page fact sheet is the second in a series discussing how Extension can improve high water users’ engagement in water conservation with a focus on high water users’ water-related behavior and willingness to act. Written by Pei-wen Huang and Alexa J. Lamm, and published by the Department of Agricultural Education and Communication, July 2016. AEC594/WC256: Engaging High Water Users in Water Conservation #2: High Water Users' Water-Related Behaviors and Willingness to Act (ufl.edu)

Greywater treatment using a moving bed biofilm reactor at a university campus in Brazil

Water reuse can contribute as an important approach and practice to the reduction of the pressures on water resources lowering the demand for potable water for purposes that do not require water's high quality. However the greywater reuse has been rarely applied in Brazil. Therefore, the main objective of this study was to evaluate a greywater collection and treatment system from lavatories, showers and washing machine aiming the non-potable reuse. The objectives were to characterize the quality and quantity of greywater from different sources, to monitor a pilot system for synthetic greywater treatment and to analyze the quality of the effluent after treatment. The pilot system implemented in a building at University of Sao Paulo allowed to segregate greywater collection and characterization. To evaluate the greywater production water flow meters were installed in the water inlet of each greywater source. The treatment system included a moving bed biofilm reactor and a settling tank at pilot scale. The evaluation of greywater treatment was conducted based on the monitoring of physicochemical and microbiological water quality parameters during the operation of the experimental system. Based on the results, amongst the three greywater sources, the water from showers had the highest E. coli concentration while the lavatories water had the highest total coliforms concentration. The removal efficiencies of BOD and COD were 59% e 70% respectively. The phosphorus removal during the experimental period was low. Nevertheless the water quality produced is viable to be applied for outdoor purposes - landscape and garden irrigation in household, commercial and institutional buildings and the results were satisfactory according to Brazilian standard. The treatment showed stability and reliability ensuring the potential for a safe reuse if appropriate operation and monitoring of the treatment system is performed.

Evapotranspiration of urban lawns in a semi-arid environment: An in situ evaluation of microclimatic conditions and watering recommendations

As many regions worldwide are increasingly affected by water scarcity caused by unprecedented climate change and population growth, current practices of landscape irrigation need to be evaluated to develop scientifically based water-saving recommendations. We compared widely used evapotranspiration (ET) based guidelines of turfgrass watering requirements with ET from 8 irrigated turfgrass lawns (4 unshaded and 4 shaded by various degree) measured in situ by portable chambers in the Los Angeles Metropolitan area. ET from unshaded lawns was 40% higher than recommended irrigation inputs and ET from shaded lawns was mostly within recommended ranges. We evaluated the microclimate coefficient (kmc), a factor used to adjust ET from reference surfaces to local microclimatic conditions. While in situ kmc was mostly within the ranges recommended for California, (1) kmc ranges for particular landscape types deviated from observations, (2) minimum and maximum kmc were beyond recommended ranges, and (3) kmc had clear seasonal changes overlooked by current methodology. We propose a method to quantitatively estimate the effect of shade on kmc and improved categories and coefficients for applying the landscape coefficient method under realistic urban conditions.

Informing Extension Program Development Through Audience Segmentation: Targeting High Water Users

Human reliance on water has led to water issues globally. Although extension professionals have made efforts successfully to educate the general public about water conservation to enhance water resource sustainability, difficulty has been found in reaching high water users, defined as residents irrigating excessively to their landscape irrigation needs without awareness of the environmental impacts. This study sought to identify differences in water conservation behavior engagement between the general public and high water users to facilitate the development of extension programs targeting high water users. Florida residents (N = 516) and high water users in Florida (N = 512) were surveyed for this descriptive and comparative study. Respondents were asked to indicate their current engagement in water use behavior, water conservation strategies, and the likelihood of engaging in water conservation and related societal behaviors. Compared to the general public, high water users reported a higher frequency of engagement in water use behaviors, and were less likely to engage in water conservation and related societal behaviors. Based on the findings it is recommended that extension professionals segment the high water users from the general public as a specific clientele and develop educational programs relevant to their specific needs and behavioral patterns.

Comparing Three Approaches of Evapotranspiration Estimation in Mixed Urban Vegetation: Field-Based, Remote Sensing-Based and Observational-Based Methods

Despite being the driest inhabited continent, Australia has one of the highest per capita water consumptions in the world. In addition, instead of having fit-for-purpose water supplies (using different qualities of water for different applications), highly treated drinking water is used for nearly all of Australia’s urban water supply needs, including landscape irrigation. The water requirement of urban landscapes, particularly urban parklands, is of growing concern. The estimation of evapotranspiration (ET) and subsequently plant water requirements in urban vegetation needs to consider the heterogeneity of plants, soils, water, and climate characteristics. This research contributes to a broader effort to establish sustainable irrigation practices within the Adelaide Parklands in Adelaide, South Australia. In this paper, two practical ET estimation approaches are compared to a detailed Soil Water Balance (SWB) analysis over a one year period. One approach is the Water Use Classification of Landscape Plants (WUCOLS) method, which is based on expert opinion on the water needs of different classes of landscape plants. The other is a remote sensing approach based on the Enhanced Vegetation Index (EVI) from Moderate Resolution Imaging Spectroradiometer (MODIS) sensors on the Terra satellite. Both methods require knowledge of reference ET calculated from meteorological data. The SWB determined that plants consumed 1084 mm·yr−1 of water in ET with an additional 16% lost to drainage past the root zone, an amount sufficient to keep salts from accumulating in the root zone. ET by MODIS EVI was 1088 mm·yr−1, very close to the SWB estimate, while WUCOLS estimated the total water requirement at only 802 mm·yr−1, 26% lower than the SWB estimate and 37% lower than the amount actually added including the drainage fraction. Individual monthly ET by MODIS was not accurate, but these errors were cancelled out to give good agreement on an annual time step. We conclude that the MODIS EVI method can provide accurate estimates of urban water requirements in mixed landscapes large enough to be sampled by MODIS imagery with 250-m resolution such as parklands and golf courses.

Quantifying water volumes of small lakes in the inner Aral Sea Basin, Central Asia, and their potential for reaching water and food security

In the inner Aral Sea Basin of Central Asia, numerous small lakes scattered over the irrigated landscape supply diverse ecosystem services for humans and nature. This study aimed to estimate the water volumes and assess the potentials of these small lakes for instance as irrigation reserve during the ever-recurring periods of water scarcity in the ecologically endangered Amudarya Delta. Bathymetric measurements gathered in the Khorezm region, Northwest Uzbekistan, permitted developing a statistical relationship between the surface and volume of the lakes. Landsat satellite data enabled for classifying the water bodies and hence deriving lake volumes over the study area. In 2002, the lakes stored ~0.032 km3 water during the winter season, but ~0.057 km3 during the main, 5–6 months spanning irrigation period. The area-wide increase in lake volumes during the irrigation period underlined the magnitude to which the currently practiced, inefficient use of irrigation water, produces excess water that in turn contributes to the existence of the small, mesotrophic lakes. Based on crop water requirements, calculations showed that the reuse of lake water may compensate for water-scarce situations, albeit to a certain extend only. An increased share (13 % above average) of water-intensive rice fields in the vicinity of the lakes substantiated that some lakes are already used in this way. It is argued that, in case of sufficient water quality, as indicated by other studies, more targeted exploration of such lake water can help simultaneously both, increasing food and water security of the households surrounding the lakes and safeguarding a supply to maintain different ecosystem functions. Integrated management of all water resources may reduce excess irrigation water supply to the region, which in turn may lessen the dependency of Central Asian downstream countries on transboundary water and supply water resources for the ecosystems in the river deltas.

Classifying Residents who use Landscape Irrigation: Implications for Encouraging Water Conservation Behavior.

Large amounts of water applied as urban irrigation can often be reduced substantially without compromising esthetics. Thus, encouraging the adoption of water-saving technologies and practices is critical to preserving water resources, yet difficult to achieve. The research problem addressed in this study is the lack of characterization of residents who use urban irrigation, which hinders the design of effective behavior change programs. This study examined audience segmentation as an approach to encouraging change using current residential landscape practices. K-means cluster analysis identified three meaningful subgroups among residential landscape irrigation users (N=1,063): the water considerate majority (n=479, 45%), water savvy conservationists (n=378, 36%), and unconcerned water users (n=201, 19%). An important finding was that normative beliefs, attitudes, and perceived behavioral control characteristics of the subgroups were significantly different with large and medium practical effect sizes. Future water conservation behaviors and perceived importance of water resources were also significantly different among subgroups. The water considerate majority demonstrated capacity to conserve, placed high value on water, and were likely to engage in behavior changes. This article contributes to the literature on individuals who use residential landscape irrigation, an important target audience with potential to conserve water through sustainable irrigation practices and technologies. Findings confirm applicability of the capacity to conserve water to audience segmentation and extend this concept by incorporating perceived value of water resources and likelihood of conservation. The results suggest practical application to promoting residential landscape water conservation behaviors based on important audience characteristics.

Soil Moisture Sensor Irrigation Controllers and Reclaimed Water; Part I: Field-plot Study

Most soil moisture sensor systems (SMSs) marketed for landscape irrigation respond to the dielectric permittivity of the soil. Compared to potable water (PW), reclaimed water (RW) may contain more salts, which can modify the dielectric permittivity of the soil and, hence, alter the readings of SMSs when measuring the soil water content. The main objectives of this experiment were to evaluate the functionality of four SMS brands and to quantify potential irrigation savings. Secondary objectives were to analyze the behavior consistency of three units within a brand to control irrigation, and to compare the brands. The experiment was carried out in Gainesville, Florida, under turfgrass plots irrigated with PW in 2009 and RW with an average salinity of 0.75 dS/m during 2010. Four SMS brands (Acclima, AquaSpy, Baseline, and Dynamax) were selected and compared to a treatment without sensor feedback (WOS). Even though replicates of AquaSpy were statistically different under both PW and RW, all SMSs tested applied significantly less water than WOS. Water savings ranged 46%-78% under PW, and 45%-68% under RW. Therefore, SMSs can be a useful tool for conserving water on turfgrass irrigated with either PW or RW.

Impacts of Urban Water Conservation Strategies on Energy, Greenhouse Gas Emissions, and Health: Southern California as a Case Study.

To determine how urban water conservation strategies in California cities can affect water and energy conservation efforts, reduce greenhouse gas emissions, and benefit public health. We expanded upon our 2014 health impact assessment of California's urban water conservation strategies by comparing the status quo to 2 options with the greatest potential impact on the interrelated issues of water and energy in California: (1) banning landscape irrigation and (2) expanding alternative water sources (e.g., desalination, recycled water). Among the water conservation strategies evaluated, expanded use of recycled water stood out as the water conservation strategy with potential to reduce water use, energy use, and greenhouse gas emissions, with relatively small negative impacts for the public's health. Although the suitability of recycled water for urban uses depends on local climate, geography, current infrastructure, and finances, analyses similar to that presented here can help guide water policy decisions in cities across the globe facing challenges of supplying clean, sustainable water to urban populations.

Evaluation of Microbial Risk Assessment Techniques and Applications

This investigation reviewed and evaluated methodologies used for microbial risk assessment with respect to their applicability for reclaimed water applications. The investigation was comprised of five primary components: a comprehensive database of articles, reports and books describing microbial risk assessment methodologies was established and reviewed. Risk assessment techniques and models were identified for estimating the public health risk from exposure to microorganisms via reclaimed water applications. Two models were identified for further evaluation: a static (individual based) and a dynamic (population based).In the third component, the two models were evaluated to differentiate between the conditions under which models predict similar and substantially different estimations of risk. Through numerical simulation, exposure/pathogen combinations were identified when it may be appropriate to use the less complex, static model. Case study risk assessment scenarios demonstrated the model selection process for three realistic, yet hypothetical reclaimed water scenarios. The fourth component presents a constraint analysis for existing reuse regulations. The constraint analysis is carried out by documenting the existing reuse regulations. The constraint analysis is carried out by documenting the existing regs in three states for landscape irrigation and uses that comparison as a starting point to identify how microbial risk assessment may be useful within the context of existing and potential future water reuse regulations. The investigation concludes by identifying criteria for a computer interface that would allow regulatory and/or municipal agencies/utilities to take advantage of the analysis discussed in the report. This title belongs to WERF Research Report Series ISBN: 9781780404141 (eBook) ISBN: 9781843396840 (Print)