Effect of graywater irrigation on soil quality and fate and transport of surfactants in soil

2012 Summer.Includes bibliographical references.While interest in and adoption of graywater reuse for irrigation has rapidly grown in recent years, little is known about the long-term effects of graywater irrigation. Concerns exist in relation to the presence of pathogenic organisms, fate of personal care products, and accumulation of salts. The purpose of this research was to evaluate the long-term effects of graywater irrigation to soil quality. The specific objectives were to evaluate the effects of graywater application on physical and chemical quality of soil, including surfactants, salts and boron accumulation, organic matter leaching and soil hydrodynamic properties in real environment in the field, in controlled environment in the greenhouse and column studies. In addition, fate and transport of surfactants in soil were investigated including how surfactant characteristics impacts mobility in soil of varying types. Graywater irrigation was found to significantly increase sodium in soil at households with graywater systems in place for more than five years; however SAR was not high enough in any of the sampling locations to raise concern about soil quality or plant health. There is a potential for salts, N, and B to leach through soil when graywater is applied for irrigation. A portion of the applied N is assimilated by plants, but leaching of N was observed. Graywater irrigation was also found to significantly increase surfactants in soil. Surfactants mainly accumulated in surface soil (0-15 cm) compared to depth soil. While surfactants have high sorption capacity due to their hydrophobic characteristics, they can be transported through soil if a large amount of water is applied. Among the surfactants measured in this study, AS and AES had the highest mobility. Mobility of surfactants in soil decreased when their number of ethoxylated groups increased. Adding organic matter to the soil increased sorption capacity of soil, as a result, more surfactants retained in the soil columns. Antimicrobials, including triclosan and triclocarban were detected in graywater irrigated areas only in surface soil samples, but not freshwater irrigated areas

Worldwide Regulations and Guidelines for Agricultural Water Reuse: A Critical Review

Water reuse is gaining momentum as a beneficial practice to address the water crisis, especially in the agricultural sector as the largest water consumer worldwide. With recent advancements in wastewater treatment technologies, it is possible to produce almost any water quality. However, the main human and environmental concerns are still to determine what constituents must be removed and to what extent. The main objectives of this study were to compile, evaluate, and compare the current agricultural water reuse regulations and guidelines worldwide, and identify the gaps. In total, 70 regulations and guidelines, including Environmental Protection Agency (EPA), International Organization for Standardization (ISO), Food and Agriculture Organization of the United Nations (FAO), World Health Organization (WHO), the United States (state by state), European Commission, Canada (all provinces), Australia, Mexico, Iran, Egypt, Tunisia, Jordan, Palestine, Oman, China, Kuwait, Israel, Saudi Arabia, France, Cyprus, Spain, Greece, Portugal, and Italy were investigated in this study. These regulations and guidelines were examined to compile a comprehensive database, including all of the water quality monitoring parameters, and necessary treatment processes. In summary, results showed that the regulations and guidelines are mainly human-health centered, insufficient regarding some of the potentially dangerous pollutants such as emerging constituents, and with large discrepancies when compared with each other. In addition, some of the important water quality parameters such as some of the pathogens, heavy metals, and salinity are only included in a small group of regulations and guidelines investigated in this study. Finally, specific treatment processes have been only mentioned in some of the regulations and guidelines, and with high levels of discrepancy.https://doi.org/10.3390/w1204097

Role of Models in the Decision-Making Process in Integrated Urban Water Management: A Review

Managing urban water systems in which stormwater, wastewater, and drinking water sectors affect each other is a difficult task that requires the right modeling tools for decision making. Integrated urban water management models (IUWMs) are tools that allow decision makers to demonstrate the effectiveness of various management, operational and design strategies. Although models are useful tools, the wide range of available models with many different capabilities make it challenging for the users to select an appropriate model for their specific objectives. In this review we investigated the capabilities of popular models in IUWM. We developed a comprehensive list of indicators to compare the capabilities of the models. We also analyzed the application of these models in a comparative way and evaluated their input requirements. Finally, we provided a procedure to select the appropriate model in the management environment based on the user’s needs. In summary, the results show that most of the models’ applications are focused on supply and demand, wastewater management, and stormwater management. Very few models consider social factors and policy aspects in IUWM. While each model has its own advantages, we found some of them, such as MIKE Urban, Hydro Planner, and Aqua Cycle, to be more comprehensive. Nevertheless, there are still gaps in the models in areas such as water-energy nexus, evaluating ecosystem services, including socioeconomic factors and sustainability analysis.https://doi.org/10.3390/w1309125

Role of Models in the Decision-Making Process in Integrated Urban Water Management: A Review

Managing urban water systems in which stormwater, wastewater, and drinking water sectors affect each other is a difficult task that requires the right modeling tools for decision making. Integrated urban water management models (IUWMs) are tools that allow decision makers to demonstrate the effectiveness of various management, operational and design strategies. Although models are useful tools, the wide range of available models with many different capabilities make it challenging for the users to select an appropriate model for their specific objectives. In this review we investigated the capabilities of popular models in IUWM. We developed a comprehensive list of indicators to compare the capabilities of the models. We also analyzed the application of these models in a comparative way and evaluated their input requirements. Finally, we provided a procedure to select the appropriate model in the management environment based on the user’s needs. In summary, the results show that most of the models’ applications are focused on supply and demand, wastewater management, and stormwater management. Very few models consider social factors and policy aspects in IUWM. While each model has its own advantages, we found some of them, such as MIKE Urban, Hydro Planner, and Aqua Cycle, to be more comprehensive. Nevertheless, there are still gaps in the models in areas such as water-energy nexus, evaluating ecosystem services, including socioeconomic factors and sustainability analysis

Assessing Crop Water Productivity under Different Irrigation Scenarios in the Mid–Atlantic Region

The continuous growth of irrigated agricultural has resulted in decline of groundwater levels in many regions of Maryland and the Mid–Atlantic. The main objective of this study was to use crop water productivity as an index to evaluate different irrigation strategies including rainfed, groundwater, and recycled water use. The Soil and Water Assessment Tool (SWAT) was used to simulate the watershed hydrology and crop yield. It was used to estimate corn and soybean water productivity using different irrigation sources, including treated wastewater from adjacent wastewater treatment plants (WWTPs). The SWAT model was able to estimate crop water productivity at both subbasin and hydrologic response unit (HRU) levels. Results suggest that using treated wastewater as supplemental irrigation can provide opportunities for improving water productivity and save fresh groundwater sources. The total water productivity (irrigation and rainfall) values for corn and soybean were found to be 0.617 kg/m3 and 0.173 kg/m3, respectively, while the water productivity values for rainfall plus treated wastewater use were found to be 0.713 kg/m3 and 0.37 kg/m3 for corn and soybean, respectively. The outcomes of this study provide information regarding enhancing water management in similar physiographic regions, especially in areas where crop productivity is low due to limited freshwater availability

Stormwater Green Infrastructure Resilience Assessment: A Social-Ecological Framework for Urban Stormwater Management

Urban areas are increasingly vulnerable to the effects of climate change. Stormwater Green infrastructure (SWGI) is seen as an approach to increase the climate resilience of urban areas, because they can buffer precipitation changes brought on by climate change. However, SWGI features themselves need to be resilient to climate change to be able to contribute to the resilience of cities. Thus, we aimed to develop a SWGI resilience assessment framework that could be used to identify challenges and to inform decisionmakers’ efforts to enhance resilience. We developed a resilience assessment framework based upon a resilience matrix approach to recognize effective resilience categories for SWGI by reviewing the literature on critical functionality and barriers to implementation and operation. These categories for SWGI included policy, design, maintenance, economic factors and social factors that influence SWGI functionality. We then identified specific aspects under each category that could be used for assessing SWGI resilience, recognizing that SWGI has critical functionalities and factors controlling its viability. Unlike other SWGI assessment frameworks that are focused on ecosystem services as a final outcome, we worked from a socio-ecological perspective in order to include socio-economic and policy factors and design and planning aspects that affect service provision. Developing a resilience assessment framework is critical for management because it can reveal the specific challenges facing SWGI resilience that have traditionally been overlooked, such as maintenance and social factors. This specific framework can also lead to efficient planning and management by identifying interrelations and hierarchical relationships of categories that influence resilience. Application of this framework will rely upon expert input to connect broad dimensions with specific indicators for SWGI to local priorities in resilience planning

Developing a Decision Support System for Economic Analysis of Irrigation Applications in Temperate Zones

Climate variability and farmers’ desire to improve the crop yield have resulted in an increase in irrigated agriculture in the mid-Atlantic region. However, the huge initial capital cost associated with the installation and operation of irrigation systems is generally prohibitive, with most farmers finding difficulty in justifying the expenditure, and uncertainty of the overall return on their investment. The objective of this study was to develop a decision tool for farmers in temperate regions to evaluate the cost-benefit of irrigation installations. The developed irrigation economic model involved the development of an economic component that balances the expected economic return, based on anticipated crop yield increases due to supplemental irrigation, versus the water, maintenance, and capital costs associated with the irrigation system. Model development included the input of relevant data and required local calibration. Soil and Water Assessment Tool (SWAT) output files were used as the basis for data input into the irrigation economic model. An irrigation-scheduling component was incorporated into the model to prescribe irrigation volumes for each agricultural field defined within the area of interest. The economic component of the model identifies and prioritizes those fields in which supplemental irrigation will result in the greatest economic return in terms of increased agricultural production and revenue. The study is conducted on the Pocomoke river basin in the Coastal Plain of Maryland’s eastern shore. Results showed that irrigation system selection was mainly influenced by cost of water and irrigation installation costs, and to a lesser extent by physical characteristics of the terrain and the associated properties

Developing a Multicriteria Decision Analysis Framework to Evaluate Reclaimed Wastewater Use for Agricultural Irrigation: The Case Study of Maryland

Groundwater is the main source of irrigation and residential use in the Eastern Shore Maryland, which is experiencing challenges regarding overuse, saltwater intrusion, and diminishing productivity. The Chesapeake Bay is also facing the problem of water pollution due to pollutant loading from agricultural fields and wastewater treatment plants (WWTPs). Using recycled water for irrigation has the potential to alleviate the pressure on groundwater and reduce pollutant loading. The objective of this study was to develop a decision tool to explore the use of recycled water for agricultural irrigation in Maryland using Multicriteria Decision Analysis (MCDA) integrated with Geographical Information Systems (GIS). Four main evaluation criteria were included in the GIS-MCDA framework: agricultural land cover, climate, groundwater vulnerability, and characteristics of the WWTPs as sources of recycled water. Groundwater vulnerability zones were developed using the groundwater well density, water extraction data, and the aquifer information. Then, the most suitable areas for irrigation using recycled water were identified. About 13.5% and 32.9% of agricultural land was, respectively, found to be “highly” and “moderately” suitable for irrigation with recycled water when WWTPs were categorized based on their treatment process information. The results provide a useful decision tool to promote the use of recycled water for agricultural irrigation.https://doi.org/10.3390/hydrology801000

Modeling the Impacts of Climate Change on Crop Yield and Irrigation in the Monocacy River Watershed, USA

Crop yield depends on multiple factors, including climate conditions, soil characteristics, and available water. The objective of this study was to evaluate the impact of projected temperature and precipitation changes on crop yields in the Monocacy River Watershed in the Mid-Atlantic United States based on climate change scenarios. The Soil and Water Assessment Tool (SWAT) was applied to simulate watershed hydrology and crop yield. To evaluate the effect of future climate projections, four global climate models (GCMs) and three representative concentration pathways (RCP 4.5, 6, and 8.5) were used in the SWAT model. According to all GCMs and RCPs, a warmer climate with a wetter Autumn and Spring and a drier late Summer season is anticipated by mid and late century in this region. To evaluate future management strategies, water budget and crop yields were assessed for two scenarios: current rainfed and adaptive irrigated conditions. Irrigation would improve corn yields during mid-century across all scenarios. However, prolonged irrigation would have a negative impact due to nutrients runoff on both corn and soybean yields compared to rainfed condition. Decision tree analysis indicated that corn and soybean yields are most influenced by soil moisture, temperature, and precipitation as well as the water management practice used (i.e., rainfed or irrigated). The computed values from the SWAT modeling can be used as guidelines for water resource managers in this watershed to plan for projected water shortages and manage crop yields based on projected climate change conditions.https://doi.org/10.3390/cli812013

Modeling the Impacts of Climate Change on Crop Yield and Irrigation in the Monocacy River Watershed, USA

Crop yield depends on multiple factors, including climate conditions, soil characteristics, and available water. The objective of this study was to evaluate the impact of projected temperature and precipitation changes on crop yields in the Monocacy River Watershed in the Mid-Atlantic United States based on climate change scenarios. The Soil and Water Assessment Tool (SWAT) was applied to simulate watershed hydrology and crop yield. To evaluate the effect of future climate projections, four global climate models (GCMs) and three representative concentration pathways (RCP 4.5, 6, and 8.5) were used in the SWAT model. According to all GCMs and RCPs, a warmer climate with a wetter Autumn and Spring and a drier late Summer season is anticipated by mid and late century in this region. To evaluate future management strategies, water budget and crop yields were assessed for two scenarios: current rainfed and adaptive irrigated conditions. Irrigation would improve corn yields during mid-century across all scenarios. However, prolonged irrigation would have a negative impact due to nutrients runoff on both corn and soybean yields compared to rainfed condition. Decision tree analysis indicated that corn and soybean yields are most influenced by soil moisture, temperature, and precipitation as well as the water management practice used (i.e., rainfed or irrigated). The computed values from the SWAT modeling can be used as guidelines for water resource managers in this watershed to plan for projected water shortages and manage crop yields based on projected climate change conditions