Environmental indices in irrigation management

Irrigation management calls for objective criteria capable of representing the economy, reliability, and productivity of irrigation systems. These criteria must be compatible with long-term sustainability and conservation goals. The criteria representing the above goals are the economic effect of management on yield reduction, economic effect, and reliability referring to plant growth and operation of the network. In this study environmental indices are introduced to express the above criteria in quantitative terms. The inclusion of these indices at the farm and network level create a multicriteria framework for decision-making based on composite programming. An experimental study was conducted during the irrigation periods of 1989 and 1990 in Chania, Greece, concerning water delivered to 40 experimental plots, soil moisture content at the rootzone, and irrigation system operational failures. The data collected in real time were used for the calculation of the corresponding environmental indices. The variation in time and space is high and resulted in up to 62% of yield loss and low system performance (up to 7% of system temporal reliability). The study indicated that environmental indices could be incorporated to select alternatives and also to develop policies on water delivery. The final decision involves a trade-off analysis between cost of application and desired system performance. Measures of both primary objectives can be obtained using environmental indices that represent system operation aggregation at its basic levels (on farm and network).     

Emergy Assessment of a Wheat-Maize Rotation System with Different Water Assignments in the North China Plain

Sustainable water use is seriously compromised in the North China Plain (NCP) due to the huge water requirements of agriculture, the largest use of water resources. An integrated approach which combines the ecosystem model with emergy analysis is presented to determine the optimum quantity of irrigation for sustainable development in irrigated cropping systems. Since the traditional emergy method pays little attention to the dynamic interaction among components of the ecological system and dynamic emergy accounting is in its infancy, it is hard to evaluate the cropping system in hypothetical situations or in response to specific changes. In order to solve this problem, an ecosystem model (Vegetation Interface Processes (VIP) model) is introduced for emergy analysis to describe the production processes. Some raw data, collected by investigating or observing in conventional emergy analysis, may be calculated by the VIP model in the new approach. To demonstrate the advantage of this new approach, we use it to assess the wheat-maize rotation cropping system at different irrigation levels and derive the optimum quantity of irrigation according to the index of ecosystem sustainable development in NCP. The results show, the optimum quantity of irrigation in this region should be 240–330 mm per year in the wheat system and no irrigation in the maize system, because with this quantity of irrigation the rotation crop system reveals: best efficiency in energy transformation (transformity = 6.05E + 4 sej/J); highest sustainability (renewability = 25%); lowest environmental impact (environmental loading ratio = 3.5) and the greatest sustainability index (Emergy Sustainability Index = 0.47) compared with the system in other irrigation amounts. This study demonstrates that application of the new approach is broader than the conventional emergy analysis and the new approach is helpful in optimizing resources allocation, resource-savings and maintaining agricultural sustainability.     

MOTIVATING REDUCTIONS IN DRAIN WATER WITH BLOCK-RATE PRICES FOR IRRIGATION WATER1

ABSTRACT: Increasing block-rate prices for irrigation water were implemented during 1989 in a 10,000-acre irrigation district in California's San Joaquin Valley. The program motivated improvements in irrigation practices that reduced the volume of water delivered to farm fields and the volume of drain water collected in on-farm drainage systems. The ratio of net crop water requirements to field deliveries increased from 0.65 in 1988 to 0.73 in 1989. The volume of drain water collected at a subset of 20 drainage systems was reduced by 351.1 acre-feet (11.5 percent). Estimated loads of salt, boron, and selenium were reduced by 2,407 tons (11.0 percent), 3.33 tons (11.0 percent), and 0.07 tons (9.2 percent).     

Simulating the Impacts of Irrigation Levels on Soybean Production in Texas High Plains to Manage Diminishing Groundwater Levels

There is an increasing need to strategize and plan irrigation systems under varied climatic conditions to support efficient irrigation practices while maintaining and improving the sustainability of groundwater systems. This study was undertaken to simulate the growth and production of soybean [Glycine max (L.)] under different irrigation scenarios. The objectives of this study were to calibrate and validate the CROPGRO‐Soybean model under Texas High Plains’ (THP) climatic conditions and to apply the calibrated model to simulate the impacts of different irrigation levels and triggers on soybean production. The methodology involved combining short‐term experimental data with long‐term historical weather data (1951–2012), and use of mechanistic crop growth simulation algorithms to determine optimum irrigation management strategies. Irrigation was scheduled based on five different plant extractable water levels (irrigation threshold [ITHR]) set at 20%, 35%, 50%, 65%, and 80%. The calibrated model was able to satisfactorily reproduce measured leaf area index, biomass, and evapotranspiration for soybean, indicating it can be used for investigating different strategies for irrigating soybean in the THP. Calculations of crop water productivity for biomass and yield along with irrigation water use efficiency indicated soybean can be irrigated at ITHR set at 50% or 65% with minimal yield loss as compared to 80% ITHR, thus conserving water and contributing toward lower groundwater withdrawals. Editor's note: This paper is part of the featured series on Optimizing Ogallala Aquifer Water Use to Sustain Food Systems. See the February 2019 issue for the introduction and background to the series.     

TECHNICAL AND INSTITUTIONAL ASPECTS OF SEWAGE EFFLUENT-IRRIGATION WATER EXCHANGE,TUCSON REGION1

ABSTRACT .Many growing municipalities near irrigated agriculture are advocating a transfer of water now utilized for irrigation to municipal use. Alternatives are presented whereby this water can be transferred to municipal use in exchange for treated sewage effluent. The irrigation water would in effect be cycled through the municipal system prior to use on the farms. A case study of the Tucson region illustrates the relevant legal, economic and technical aspects. Effluent could be delivered to irrigators in Avra Valley at a cost less than that now paid for water pumped from declining water tables. In return the City of Tucson could import ground water now being used for irrigation through an existing pipeline which presently cannot be used because of a court injunction obtained by the irrigators. It appears that such an exchange agreement could be made without modification of existing statutory law. Similar exchange arrangements may prove to be feasible in other regions containing irrigated agriculture. Increased efficiency of water use can be achieved avoiding external effects which commonly arise in a direct transfer and are difficult to evaluate. High quality water is allocated to municipal use whereas nutrient-rich sewage effluent is transferred to irrigation.     

Nitrate leaching beneath a containerized nursery crop receiving trickle or overhead irrigation

Container production of nursery crops is intensive and a potential source of nitrogen release to the environment. This study was conducted to determine if trickle irrigation could be used by container nursery producers as an alternative to standard overhead irrigation to reduce nitrogen release into the environment. The effect of overhead irrigation and trickle irrigation on leachate nitrate N concentration, flow-weighted nitrate N concentration, leachate volume, and plant growth was investigated using containerized rhododendron (Rhododendron catawbiense Michx. 'Album') supplied with a controlled-release fertilizer and grown outdoors on top of soil-monolith lysimeters. Leachate was collected over two growing seasons and overwinter periods, and natural precipitation was allowed as a component of the system. Precipitation accounted for 69% of the water entering the overhead-irrigated system and 80% of the water entering the trickle-irrigated system. Leachate from fertilized plants exceeded the USEPA limit of 10 mg L(-1) at several times and reached a maximum of 26 mg L(-1) with trickle irrigation. Average annual loss of nitrate N in leachate for fertilized treatments was 51.8 and 60.5 kg ha(-1) for the overhead and trickle treatments, respectively. Average annual flow-weighted concentration of nitrate N in leachate of fertilized plants was 7.2 mg L(-1) for overhead irrigation and 12.7 mg L(-1) for trickle irrigation. Trickle irrigation did not reduce the amount of nitrate N leached from nursery containers when compared with overhead irrigation because precipitation nullified the potential benefits of reduced leaching fractions and irrigation inputs provided under trickle irrigation.     

昆山市农产品产地环境质量监测与评价

为研究昆山市农产品产地环境质量,采用采样分析方法,对昆山市农产品产地的代表性土壤、灌溉水、渔业水质量进行了定点取样分析检测,在此基础上依据国家相关环境质量标准进行了单因子污染指数法和综合污染指数法评价。结果表明,该市58.1%的耕层土壤为安全、清洁,36.6%的耕层土壤处于警戒限,为尚清洁,3.8%的耕层土壤为轻污染,1.5%的耕层土壤为中污染;76.0%的灌溉水为安全、清洁,24.0%的灌溉水处于警戒限,为尚清洁;73.5%的渔业水为安全、清洁,23.5%的渔业水处于警戒限,为尚清洁,3%的渔业水为轻污染。     

Use of Predictive Weather Uncertainties in an Irrigation Scheduling Tool Part II: An Application of Metrics and Adjoints

We apply predictive weather metrics and land model sensitivities to improve the Colorado State University Water Irrigation Scheduler for Efficient Application (WISE). WISE is an irrigation decision aid that integrates environmental and user information for optimizing water use. Rainfall forecasts and verification performance metrics are used to estimate predictive rainfall probabilities that are used as input data within the irrigation decision aid. These input data errors are also used within a land model sensitivity study to diagnose important prognostic water movement behaviors for irrigation tool development purposes simultaneously performing the analysis in space and time. Thus, important questions such as “how long can a crop water application be delayed while maintaining crop yield production?” are addressed by evaluating crop growth stage interactions as a function of soil depth (i.e., space), rainfall events (i.e., time), and their probabilistic uncertainties. Editor’s note : This paper is part of the featured series on Optimizing Ogallala Aquifer Water Use to Sustain Food Systems. See the February 2019 issue for the introduction and background to the series.     

Spatial assessment of groundwater quality in Guna Tana landscape

This study focuses on investigating the quality of groundwater for irrigation and drinking water purposes. Spatial distribution of physicochemical and microbiological parameters was assessed from samples collected from springs, hand‐dug wells, and boreholes found the Guna Tana landscape. A total of 70 samples were considered for physical, chemical, and bacteriological water quality determination. The results revealed that most of the groundwater quality index (WQI) values lie between good and excellent. The maximum, minimum, mean, and standard deviation of each water quality parameter were prepared for evaluating groundwater quality. According to the WQI values, more than 83% of the water samples were classified as excellent water for drinking. More than 92% of the water samples showed low sodium hazards for irrigation and about 48% and 46% of the water samples were classified as within the excellent and good water classes for irrigation based on their electrical conductance levels. Therefore, the groundwater that is found in the Guna Tana landscape could be used for drinking and irrigation purposes without any advanced treatment.     

ESTIMATING THE DEMAND FOR IRRIGATION WATER IN THE CENTRAL VALLEY OF CALIFORNIA1

ABSTRACT: This paper computes estimates of the demand for surface irrigation water directly from disaggregated profit functions for fields in the San Joaquin Valley of California. It finds that treating delivered surface water and pumped ground water as separate, imperfectly substitutable inputs to production matters a great deal. We find substantial ranges of inelastic demand for delivered water, and thresholds across which demand then becomes highly elastic. The results imply that moves toward freer water markets could lead to large quantities reallocated from agriculture to urban uses in the Western U.S., but would require large price increases and would induce extensive ground water mining and major changes in cropping patterns. While these results are dependent on our particular model and simplifying assumptions, evidence exists that they may be robust.     

A study on operation problems of hydropower plants integrated with irrigation schemes operated in Turkey

In this study, Hydroelectric Power Plants, which have been built and integrated with irrigation schemes by the State Hydraulic Works which is a government agency and private companies in Turkey, have been examined. Technical, environmental, structural and social problems encountered during their operation have been analyzed, and appropriate solution proposals have been presented in the study for a sustainable irrigation and Hydroelectric Power Plant operation. Consequently, Hydroelectric Power Plants which have been integrated with irrigation schemes should be operated efficiently and they should be operated in attenuation with the environment. However, when hydroelectric projects are developed without preparing their necessary integrated basin management plans, then this will cause environmental, operation and maintenance, administrative, monitoring and evaluation problems. In order to ensure sustainability of hydroelectricity production and also in order to use water resources more efficiently for irrigation; it is very important to find permanent solutions to these problems.     

Life cycle assessment of Italian citrus-based products. Sensitivity analysis and improvement scenarios

Though many studies concern the agro-food sector in the EU and Italy, and its environmental impacts, literature is quite lacking in works regarding LCA application on citrus products. This paper represents one of the first studies on the environmental impacts of citrus products in order to suggest feasible strategies and actions to improve their environmental performance. In particular, it is part of a research aimed to estimate environmental burdens associated with the production of the following citrus-based products: essential oil, natural juice and concentrated juice from oranges and lemons. The life cycle assessment of these products, published in a previous paper, had highlighted significant environmental issues in terms of energy consumption, associated CO₂ emissions, and water consumption. Starting from such results the authors carry out an improvement analysis of the assessed production system, whereby sustainable scenarios for saving water and energy are proposed to reduce environmental burdens of the examined production system. In addition, a sensitivity analysis to estimate the effects of the chosen methods will be performed, giving data on the outcome of the study. Uncertainty related to allocation methods, secondary data sources, and initial assumptions on cultivation, transport modes, and waste management is analysed. The results of the performed analyses allow stating that every assessed eco-profile is differently influenced by the uncertainty study. Different assumptions on initial data and methods showed very sensible variations in the energy and environmental performances of the final products. Besides, the results show energy and environmental benefits that clearly state the improvement of the products eco-profile, by reusing purified water use for irrigation, using the railway mode for the delivery of final products, when possible, and adopting efficient technologies, as the mechanical vapour recompression, in the pasteurisation and concentration of juice.     

Leaching of pharmaceuticals and personal care products in turfgrass soils during recycled water irrigation

An important beneficial reuse of treated wastewater (recycled water) in arid and semiarid regions is landscape irrigation. However, the environmental fate, especially groundwater contamination potential, of trace contaminants such as pharmaceuticals and personal care products (PPCPs) is a significant concern that can hinder the acceptance and adoption of such reuses. In this study, we irrigated mature turfgrass plots with nonspiked tertiary treated wastewater for over 6 mo at 100 or 130% of the reference evapotranspiration rate (ETo) and collected leachate water at the 90-cm depth on a weekly basis. In the recycled water, all 14 target PPCPs were consistently found, and the mean levels of atenolol, gemfibrozil, meprobamate, carbamazepine, and sulfamethoxazole were above 100 ng L. However, only five compounds were detected in the leachate at trace levels. Trimethoprim and primidone were frequently found, whereas the detection of sulfamethoxazole, meprobamate and carbamazepine was less frequent (<50%). When detected, the overall mean concentration in the leachate was 10.2 ng L for trimethoprim, 7.1 ng L for primidone, and 2.9 to 12.4 ng L for carbamazepine, sulfamethoxazole, and meprobamate. The majority of the target PPCPs were completely removed. Given that the irrigation rates were higher than normal, this study clearly demonstrated the efficacy of turfgrass systems in attenuating PPCPs during recycled water irrigation. However, it is also apparent that some PPCPs are more susceptible to leaching than others, and these PPCPs thus merit further research attention.     

Relations of fish community composition to environmental variables in streams of central Nebraska,USA

Nine sites on streams in the Platte River Basin in central Nebraska were sampled as part of the US Geological Survey's National Water-Quality Assessment Program during 1993–1994. A combination of canonical correspondence analysis and an index of biotic integrity determined from fish community data produced complementary evaluations of water-quality conditions. Results of the canonical correspondence analysis were useful in showing which environmental variables were significant in differentiating fish communities at the nine sites. Five environmental variables were statistically significant in the analysis. Median specific conductance of water samples collected at a site accounted for the largest amount of variability in the species data. Although the percentage of the basin as cropland was not the first variable chosen in a forward selection process, it was the most strongly correlated with the first ordination axis. A rangeland-dominated site was distinguished from all others along that axis. Median orthophosphate concentration of samples collected in the year up to the time of fish sampling was most strongly correlated with the second ordination axis. The index of biotic integrity produced results that could be interpreted in terms of the relative water quality between sites. Sites draining nearly 100% cropland had the lowest scores for two individual metrics of the index of biotic integrity that were related to species tolerance. Effective monitoring of water quality could be achieved by coupling methods that address both the ecological components of fish communities and their statistical relationships to environmental factors.     

Application of game theory for a groundwater conflict in Mexico

Exploitation of scarce water resources, particularly in areas of high demand, inevitably produces conflict among disparate stakeholders, each of whom may have their own set of priorities. In order to arrive at a socially acceptable compromise, the decision-makers should seek an optimal trade-off between conflicting objectives that reflect the priorities of the various stakeholders. In this study, game theory was applied to a multiobjective conflict problem for the Alto Rio Lerma Irrigation District, located in the state of Guanajuato in Mexico, where economic benefits from agricultural production should be balanced with associated negative environmental impacts. The short period of rainfall in this area, combined with high groundwater withdrawals from irrigation wells, has produced severe aquifer overdraft. In addition, current agricultural practices of applying high loads of fertilizers and pesticides have contaminated regions of the aquifer. The net economic benefit to this agricultural region in the short-term lies with increasing crop yields, which requires large pumping extractions for irrigation as well as high chemical loading. In the longer term, this can produce economic loss due to higher pumping costs (i.e., higher lift requirements), or even loss of the aquifer as a viable source of water. Negative environmental impacts include continued diminishment of groundwater quality, and declining groundwater levels in the basin, which can damage surface water systems that support environmental habitats. The two primary stakeholders or players, the farmers in the irrigation district and the community at large, must find an optimal balance between positive economic benefits and negative environmental impacts. In this paper, game theory was applied to find the optimal solution between the two conflicting objectives among 12 alternative groundwater extraction scenarios. Different attributes were used to quantify the benefits and costs of the two objectives, and, following generation of the Pareto frontier or trade-off curve, four conflict resolution methods were then applied.     

Environmental flows for rivers and economic compensation for irrigators

Securing flows for environmental purposes from an already fully utilized river is an impossible task--unless users are either coerced into freeing up water, or offered incentives to do so. One sensible strategy for motivating users to liberate volumes is to offer them economic compensation. The right amount for that compensation then becomes a key environmental management issue. This paper analyses a proposal to restore and maintain ecosystems on a stretch of the Río Conchos in northern Mexico, downstream from a large irrigation district that consumes nearly all local flows. We present here estimates of environmental flow requirements for these ecosystems and compute compensation figures for irrigators. These figures are derived from crop-specific irrigation water productivities we statistically estimate from a large set of historical production and irrigation data obtained from the district. This work has general implications for river ecosystem management in water-stressed basins, particularly in terms of the design of fair and effective water sharing mechanisms.     

Analysis of Socioeconomic and Environmental Impacts of Waste Stabilization Pond and Unrestricted Wastewater Irrigation: Interface with Maintenance

The effluent from the waste stabilization ponds (WSPs) of the University of Nigeria, Nsukka Campus, is used for irrigation by poor rural farmers. There has been fear that the poorly maintained WSPs and the reuse practices are contributing to environmental degradation and health hazards. In this study the environmental and socioeconomic impacts of the WSPs and reuse were evaluated based on data collected from questionnaires and the literature. The engineering and agricultural properties of soil in the irrigated and nonirrigated areas were compared. Comparison of the health status of the farmers and nonfarmers, of consumers of crops irrigated with wastewater and nonconsumers was performed using Student's t test and the z-score test. The occurrences of diarrhea, typhoid fever, and malaria among the various groups were used as indices. Analyses show that the health status of the farmers and consumers is poorer than those of nonfarmers and nonconsumers at the 5% level of significance. Vegetable cultivation using WSP effluent is a means of sustenance to the farmers and provides an affordable means of satisfying their nutritional deficiencies. However, the poorly maintained WSPs create odor and mosquito nuisances, trap and destroy livestock, and flood nearby compounds with waste debris. At both 1% and 5% levels of significance, communities around the ponds (< 300 m) suffer malaria more frequently than those who live far away (> or = 300 m). Cost-benefit analysis argues in favor of improvement of WSP management and irrigation reuse of wastewater. Dredging of the ponds, training workers and farmers, and adopting appropriate maintenance and monitoring strategies will greatly enhance the socioeconomic status of the urban poor farmers.     

Water movement within the unsaturated zone in four agricultural areas of the United States

Millions of tons of agricultural fertilizer and pesticides are applied annually in the USA. Due to the potential for these chemicals to migrate to groundwater, a study was conducted in 2004 using field data to calculate water budgets, rates of groundwater recharge and times of water travel through the unsaturated zone and to identify factors that influence these phenomena. Precipitation was the only water input at sites in Indiana and Maryland; irrigation accounted for about 80% of total water input at sites in California and Washington. Recharge at the Indiana site (47.5 cm) and at the Maryland site (31.5 cm) were equivalent to 51 and 32%, respectively, of annual precipitation and occurred between growing seasons. Recharge at the California site (42.3 cm) and Washington site (11.9 cm) occurred in response to irrigation events and was about 29 and 13% of total water input, respectively. Average residence time of water in the unsaturated zone, calculated using a piston-flow approach, ranged from less than 1 yr at the Indiana site to more than 8 yr at the Washington site. Results of bromide tracer tests indicate that at three of the four sites, a fraction of the water applied at land surface may have traveled to the water table in less than 1 yr. The timing and intensity of precipitation and irrigation were the dominant factors controlling recharge, suggesting that the time of the year at which chemicals are applied may be important for chemical transport through the unsaturated zone.     

Hazardous waste indicators for national decision makers

Indicators and indices are important tools that assist decision makers to formulate and implement plans for management at local, national and international levels. Four indicators for hazardous waste management are described that have recently been adopted within the United Nations framework of Indicators of Sustainable Development. Although these four indicators will be useful tools, the need for a broader range of policy-relevant qualitative and quantitative indicators, proxy indicators and indices is outlined. The argument is advanced that in order for all nations to better manage the range of hazardous waste issues, including waste generation, export/import and disposal, a set of innovative indicators and indices is required. Useful indicators and indices are described that could be used to link and quantify likely environmental, ecosystem and health impacts and risks especially from hazardous waste disposal. Indicators are also suggested that could be used to illustrate the shift in industrial strategy away from end-of-pipe processes towards waste recycling, cleaner production and integrated life-cycle analysis. It was concluded that until the lack of reliable and harmonized data on hazardous waste is addressed, indicator development and use by national and international decision makers cannot readily be implemented.     

Performance assessment of a wastewater treatment plant producing effluent for irrigation in Egypt

A conventional activated sludge treatment facility was the subject of this study. The assessment was directed at determining the characteristics of the raw wastewater, the quality of the treated effluent and the efficiency of the various treatment units. Furthermore, the water quality along the effluent irrigation canal was monitored. The assessment of the quality of the treated effluent for irrigation is based on the guidelines established by the World Health Organization and the Egyptian decree 9/89 for the use of wastewater in agriculture. The results of the study indicated that the concentration of the raw wastewater was considered moderate. The mean values of the COD (Chemical Oxygen Demand), BOD (Biological Oxygen Demand) and total suspended solids (TSS) were around 250, 102 and 142 mg l–1, respectively. This was attributed to the high quantities of wastewater from industrial sources. The overall efficiency of the treatment facility was good. The mean residual COD, BOD and TSS were 25, 8 and 21 mg l–1 and the corresponding percentage removal values were 90, 92 and 85%, respectively. The maximum percentage removal of oil and grease was 84% with a mean residual concentration of 24 mg l–1. The total viable count (22°C and 37°C), faecal coliform and aecal streptococci were reduced by 99.9% compared to only 99.5% for Salmonella. Bacteriological examination of the dried sludge indicated a reduction of nine logs of faecal coliform and faecal streptococci, as compared to thickened sludge. Analysis of the Ni, Cu, Pb and Cr in the dried sludge indicated that their concentrations are within the permissible limits. Zinc exceeded the consent standards by 50%. The results of the analyses of samples collected at the beginning of the irrigation canal indicated insignificant changes from the characteristics of the final effluent. Samples collected at a distance of 2km along the irrigation canal showed mean reductions in the COD and BOD of 28.6 and 47%, respectively, which could be attributed to sedimentation and/or a self-purification effect. An increase in the total nitrogen, total phosphorus and total viable count was also recorded, which could be due to seepage from the agricultural land. From the data available it is evident that the treated wastewater could be used for restricted irrigation. The design and implementation of a monitoring programme is recommended.