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Author: Jacqueline Marie Brook
Publisher:
ISBN:
Category :
Languages : en
Pages : 315
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Book Description
This thesis presents two interrelated studies that consider nutrient management and seasonal changes in recharge on agricultural lands within the context of source water protection. The research focuses first on the management of the risk to groundwater quality through the implementation of various nutrient management practices and secondly considers the dynamic nature of the transport pathway to the groundwater system associated with seasonal changes in climate and hydrology. The combined results provide insight into several of the key factors influencing the protection of groundwater sources within the agricultural landscape. Field work was completed between 2009 and 2010 on an agricultural field near the City of Woodstock, Ontario. The site is located within a source water protection area; the two-year travel time zone of the Thornton Well Field which represents the primary water supply for the City of Woodstock and which has experienced chronic increases in nitrate concentrations over the last few decades. The wells are completed in glacial overburden consisting of intermingling sand and gravel till aquifers which overly a limestone bedrock aquifer. Agricultural best or beneficial management practices (BMPs) field have been implemented and monitored since 2004. The BMPs were adopted in order to reduce nitrogen losses to the aquifer, and consisted of a reduction in nitrogen fertilizer application rates over a series of agricultural fields located near the well The first study is a one year experiment designed to compare alternative nutrient management practices for corn. Combinations of fertilizer treatments with or without a legume cover crop (red clover) were assessed. The fertilizer treatments studied were: a polymer coated urea (slow-release fertilizer) applied at planting, a conventional urea applied at planting, side-dress treatment of a solution of urea and ammonium nitrate in water containing 28% nitrogen with two different application rates applied in the early summer, and a control. The legume cover crop was incorporated in the soil in the previous fall, and acts as a slow release fertilizer as nitrogen is made available to the following crop as the plants decompose. Treatments were compared based on crop yield, overall economic return, and the potential for nitrate leaching. The potential for nitrate leaching was evaluated with bi-weekly shallow soil core during the growing season, and deep soil cores taken before planting, after harvest and the following spring. The deep cores allowed changes in nitrate storage below the rooting zone to be assessed. The results of this study highlight the importance of timing of fertilizer applications and rate of fertilizer applications. Treatments which provide a delay in the release or application of fertilizer, the polymer-coated urea, the calculator-rate side-dress and the clover cover crop, were found to be advantageous. The polymer-coated urea treatments and side-dress treatments were found to reduce leaching compared to the conventional urea treatment. Treatments with the clover cover crops were not found to reduce crop yields or increase leaching potential, and lower fertilizer costs associated to this practice were found to have a positive economic effect. Plots treated with the high-rate side-dress fertilizer application lost more nitrate to the subsurface compared to the other treatment options, and an economic disadvantage was observed as yields did not compensate for higher fertilizer costs. The study highlights the advantages of the different treatments under study, which may be used to inform policy makers and farmers in the selection of economically and environmentally sustainable nutrient management BMP options. Groundwater monitoring at the site over the years has indentified interesting recharge dynamics, particularly in the vicinity of an ephemeral stream which develops annually during spring and winter melt events in a low lying area of the study site. It was hypothesized that rapid recharge could occur beneath the stream allowing for surface water to quickly reach groundwater, posing a threat to municipal water wells. The current framework of source water protection does not take into account the potential risk posed by this type recharge event. At this field site, rapid infiltration associated with this type of event may pose a risk to drinking water quality due to the proximity of the stream to the pumping wells and the nature of the aquifer. The second study examines rapid groundwater recharge processes beneath the ephemeral stream during the course of a spring melt in 2010. The goals of the study were to quantify recharge at one location beneath the stream and to assess whether temperature variations above the water table can be used as a tracer to reasonably estimate recharge during a short live recharge event. A novel housing for the temperature sensors was designed in order to deploy and position them into gravelly materials within the vadose zone, which reduced the potential for the formation of preferential pathways and permitted the retrieval of the sensors at a later date. Field data were collected during the course of the spring melt period from a network of groundwater monitoring wells and subsurface temperature sensors. Spatial and temporal changes in groundwater geochemistry, hydraulic head and temperature were were used to characterize recharge dynamics at the field site. Recharge beneath a segment of the ephemeral stream was quantified through the numerical analysis of the field data using Hydrus 1-D, a one-dimensional numerical model designed to simulate soil water flow and heat transport in variably saturated porous media. Site specific data were used to create the model domain, provide estimates of physical parameters, and to define initial and time variable boundary conditions. Model parameters were first calibrated by simulating periods where it was expected that soils would be gravity drained with minimal soil water flow, and then further refined by simulating the period when the ephemeral stream was present. A final set of parameters was determined, and the initial gravity drained conditions were re-simulated. The model was able to reproduce field observations under different flow scenarios using the final set of parameters, suggesting that the conceptual model and final model domain representative of the actual field conditions. The successful simulation of the field data sets under the different flow scenarios also increases confidence in the uniqueness of the model results. The model estimated that 0.15 m of recharge occurred beneath the instrumented site during the period between March 9th and March 22nd of 2010 when the ephemeral stream was present. This represents approximately a third of the expected total annual recharge for this location. Regional changes in hydraulic head, groundwater temperature and groundwater chemistry provided additional insight into the dynamic nature of the recharge process during the spring meld period and further illustrated the spatial variability of the aquifers' response to the stream. The study found that the use of temperature as a tracer provided useful and quantifiable insight into recharge phenomena. The results of this study suggest that high rates of rapid recharge occur beneath the ephemeral stream, and are spatially variable. This type of focused infiltration that occurs during the spring melt may represent a risk to municipal water quality if the infiltrating waters are carrying contaminants.
Author: Jacqueline Marie Brook
Publisher:
ISBN:
Category :
Languages : en
Pages : 315
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Book Description
This thesis presents two interrelated studies that consider nutrient management and seasonal changes in recharge on agricultural lands within the context of source water protection. The research focuses first on the management of the risk to groundwater quality through the implementation of various nutrient management practices and secondly considers the dynamic nature of the transport pathway to the groundwater system associated with seasonal changes in climate and hydrology. The combined results provide insight into several of the key factors influencing the protection of groundwater sources within the agricultural landscape. Field work was completed between 2009 and 2010 on an agricultural field near the City of Woodstock, Ontario. The site is located within a source water protection area; the two-year travel time zone of the Thornton Well Field which represents the primary water supply for the City of Woodstock and which has experienced chronic increases in nitrate concentrations over the last few decades. The wells are completed in glacial overburden consisting of intermingling sand and gravel till aquifers which overly a limestone bedrock aquifer. Agricultural best or beneficial management practices (BMPs) field have been implemented and monitored since 2004. The BMPs were adopted in order to reduce nitrogen losses to the aquifer, and consisted of a reduction in nitrogen fertilizer application rates over a series of agricultural fields located near the well The first study is a one year experiment designed to compare alternative nutrient management practices for corn. Combinations of fertilizer treatments with or without a legume cover crop (red clover) were assessed. The fertilizer treatments studied were: a polymer coated urea (slow-release fertilizer) applied at planting, a conventional urea applied at planting, side-dress treatment of a solution of urea and ammonium nitrate in water containing 28% nitrogen with two different application rates applied in the early summer, and a control. The legume cover crop was incorporated in the soil in the previous fall, and acts as a slow release fertilizer as nitrogen is made available to the following crop as the plants decompose. Treatments were compared based on crop yield, overall economic return, and the potential for nitrate leaching. The potential for nitrate leaching was evaluated with bi-weekly shallow soil core during the growing season, and deep soil cores taken before planting, after harvest and the following spring. The deep cores allowed changes in nitrate storage below the rooting zone to be assessed. The results of this study highlight the importance of timing of fertilizer applications and rate of fertilizer applications. Treatments which provide a delay in the release or application of fertilizer, the polymer-coated urea, the calculator-rate side-dress and the clover cover crop, were found to be advantageous. The polymer-coated urea treatments and side-dress treatments were found to reduce leaching compared to the conventional urea treatment. Treatments with the clover cover crops were not found to reduce crop yields or increase leaching potential, and lower fertilizer costs associated to this practice were found to have a positive economic effect. Plots treated with the high-rate side-dress fertilizer application lost more nitrate to the subsurface compared to the other treatment options, and an economic disadvantage was observed as yields did not compensate for higher fertilizer costs. The study highlights the advantages of the different treatments under study, which may be used to inform policy makers and farmers in the selection of economically and environmentally sustainable nutrient management BMP options. Groundwater monitoring at the site over the years has indentified interesting recharge dynamics, particularly in the vicinity of an ephemeral stream which develops annually during spring and winter melt events in a low lying area of the study site. It was hypothesized that rapid recharge could occur beneath the stream allowing for surface water to quickly reach groundwater, posing a threat to municipal water wells. The current framework of source water protection does not take into account the potential risk posed by this type recharge event. At this field site, rapid infiltration associated with this type of event may pose a risk to drinking water quality due to the proximity of the stream to the pumping wells and the nature of the aquifer. The second study examines rapid groundwater recharge processes beneath the ephemeral stream during the course of a spring melt in 2010. The goals of the study were to quantify recharge at one location beneath the stream and to assess whether temperature variations above the water table can be used as a tracer to reasonably estimate recharge during a short live recharge event. A novel housing for the temperature sensors was designed in order to deploy and position them into gravelly materials within the vadose zone, which reduced the potential for the formation of preferential pathways and permitted the retrieval of the sensors at a later date. Field data were collected during the course of the spring melt period from a network of groundwater monitoring wells and subsurface temperature sensors. Spatial and temporal changes in groundwater geochemistry, hydraulic head and temperature were were used to characterize recharge dynamics at the field site. Recharge beneath a segment of the ephemeral stream was quantified through the numerical analysis of the field data using Hydrus 1-D, a one-dimensional numerical model designed to simulate soil water flow and heat transport in variably saturated porous media. Site specific data were used to create the model domain, provide estimates of physical parameters, and to define initial and time variable boundary conditions. Model parameters were first calibrated by simulating periods where it was expected that soils would be gravity drained with minimal soil water flow, and then further refined by simulating the period when the ephemeral stream was present. A final set of parameters was determined, and the initial gravity drained conditions were re-simulated. The model was able to reproduce field observations under different flow scenarios using the final set of parameters, suggesting that the conceptual model and final model domain representative of the actual field conditions. The successful simulation of the field data sets under the different flow scenarios also increases confidence in the uniqueness of the model results. The model estimated that 0.15 m of recharge occurred beneath the instrumented site during the period between March 9th and March 22nd of 2010 when the ephemeral stream was present. This represents approximately a third of the expected total annual recharge for this location. Regional changes in hydraulic head, groundwater temperature and groundwater chemistry provided additional insight into the dynamic nature of the recharge process during the spring meld period and further illustrated the spatial variability of the aquifers' response to the stream. The study found that the use of temperature as a tracer provided useful and quantifiable insight into recharge phenomena. The results of this study suggest that high rates of rapid recharge occur beneath the ephemeral stream, and are spatially variable. This type of focused infiltration that occurs during the spring melt may represent a risk to municipal water quality if the infiltrating waters are carrying contaminants.
Author: Bradley M. Crowder
Publisher:
ISBN:
Category : Agricultural chemicals
Languages : en
Pages : 28
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Author: UNESCO
Publisher: UNESCO Publishing
ISBN: 9231004883
Category : Political Science
Languages : en
Pages : 366
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Author: Anthony J Jakeman
Publisher: Springer
ISBN: 3319235761
Category : Science
Languages : en
Pages : 756
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The aim of this book is to document for the first time the dimensions and requirements of effective integrated groundwater management (IGM). Groundwater management is a formidable challenge, one that remains one of humanity’s foremost priorities. It has become a largely non-renewable resource that is overexploited in many parts of the world. In the 21st century, the issue moves from how to simply obtain the water we need to how we manage it sustainably for future generations, future economies, and future ecosystems. The focus then becomes one of understanding the drivers and current state of the groundwater resource, and restoring equilibrium to at-risk aquifers. Many interrelated dimensions, however, come to bear when trying to manage groundwater effectively. An integrated approach to groundwater necessarily involves many factors beyond the aquifer itself, such as surface water, water use, water quality, and ecohydrology. Moreover, the science by itself can only define the fundamental bounds of what is possible; effective IGM must also engage the wider community of stakeholders to develop and support policy and other socioeconomic tools needed to realize effective IGM. In order to demonstrate IGM, this book covers theory and principles, embracing: 1) an overview of the dimensions and requirements of groundwater management from an international perspective; 2) the scale of groundwater issues internationally and its links with other sectors, principally energy and climate change; 3) groundwater governance with regard to principles, instruments and institutions available for IGM; 4) biophysical constraints and the capacity and role of hydroecological and hydrogeological science including water quality concerns; and 5) necessary tools including models, data infrastructures, decision support systems and the management of uncertainty. Examples of effective, and failed, IGM are given. Throughout, the importance of the socioeconomic context that connects all effective IGM is emphasized. Taken as a whole, this work relates the many facets of effective IGM, from the catchment to global perspective.
Author: Jorge Delgado
Publisher:
ISBN:
Category :
Languages : en
Pages : 12
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Author: WWAP
Publisher: UNESCO Publishing
ISBN: 9231002643
Category : Water quality management
Languages : en
Pages : 154
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Author: Tracy Alanna Campbell
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Across the Midwest, farmers, researchers, policy makers and communities are confronting increasing groundwater contamination due to agricultural practices, particularly the use of synthetic nitrogen fertilizer, coupled with the challenge of employing these practices to continue growing profitable crops. Additionally, not only are the impacts of agricultural practices felt at the local level-often in the form of agricultural runoff, unsafe drinking water, soil erosion, and decreased stream and lake levels-but also nationally. As agricultural runoff travels downstream to the Gulf of Mexico, excess nutrients have resulted in dead zones. It is likely that ongoing and future climate change across the Midwest will exacerbate current struggles and may leave many fields more vulnerable to nitrate leaching. Moving forward, to ensure safe drinking water and restore and protect ecosystem services, nitrogen management strategies need to be improved and implemented. The Wisconsin Central Sands (WCS) faces many of the challenges felt by communities across the Midwest when managing agricultural land with growing water quality contamination. The WCS region serves as a case study in improving nitrogen management for groundwater quality. To better identify pathways to improved groundwater quality, we incorporated on-farm research related to drivers of water quality variability, observations of soil-plant-environment interactions, agroecosystem modeling, and farmer surveys. In chapter one, we evaluated/quantified the spatiotemporal variability of nitrate concentrations in irrigation water across the WCS region. Additionally, we analyzed the influence of well depth, well casing diameter, nitrogen application rate, year and week of sampling event on nitrate concentration in irrigation water. We found that nitrate levels varied more across space than time, that nitrogen application rate was the most significant predictor of nitrate concentration, and that on average, nitrate levels in irrigation water across the WCS are 19.0 mg/L, or nearly twice the threshold for safe drinking water set by the EPA. In chapter two, we measured leaf level photosynthesis and calculated key photosynthetic parameters for two cultivars of potato grown under four nitrogen application rates. We found that nitrogen application rate (season total N), days after emergence (DAE), and temperature were significant predictors of Vcmax (maximum rate of carboxylation). We also found that at the highest level of nitrogen application (403.5 kg N/ha), both N content (%) and Vcmax declined relative to a nitrogen application rate of 336.3 kg N/ha. In chapter three, we modeled the impact of nitrogen best management practices (BMPs) with varied N rates on irrigated corn yield and nitrate leaching. To better understand the effectiveness and tradeoffs of BMPs considering increased weather variability, we used cluster analysis to group similar weather years. We found that nitrate leaching could be reduced through the use of BMPs (20%) and reduced nitrogen application rates (40%), but there was little room for mitigation during years experiencing wetter than average growing seasons. Additionally, nitrate concentration in the groundwater never reached safe/healthy levels (below 10 mg/L) in our simulations. In chapter four, we surveyed farmers on their current use of nitrogen BMPs, levels of concern towards environmental and economic challenges, as well as barriers to implementing certain BMPs. Our findings highlight that growers feel the greatest level of concern for the cost of government regulation and ineffective government policies, and 100% of respondents felt at least a little concerned about groundwater quality. While the BMP of split application was widely adopted (69%), growers perceived lack of information as a substantial barrier to adopting the practice of crediting nitrate in irrigation water.
Author: National Academies of Sciences, Engineering, and Medicine
Publisher: National Academies Press
ISBN: 0309679702
Category : Science
Languages : en
Pages : 423
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Book Description
New York City's municipal water supply system provides about 1 billion gallons of drinking water a day to over 8.5 million people in New York City and about 1 million people living in nearby Westchester, Putnam, Ulster, and Orange counties. The combined water supply system includes 19 reservoirs and three controlled lakes with a total storage capacity of approximately 580 billion gallons. The city's Watershed Protection Program is intended to maintain and enhance the high quality of these surface water sources. Review of the New York City Watershed Protection Program assesses the efficacy and future of New York City's watershed management activities. The report identifies program areas that may require future change or action, including continued efforts to address turbidity and responding to changes in reservoir water quality as a result of climate change.
Author:
Publisher:
ISBN:
Category : Eutrophication
Languages : en
Pages : 258
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Author: National Research Council
Publisher: National Academies Press
ISBN: 0309069483
Category : Science
Languages : en
Pages : 422
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Book Description
Environmental problems in coastal ecosystems can sometimes be attributed to excess nutrients flowing from upstream watersheds into estuarine settings. This nutrient over-enrichment can result in toxic algal blooms, shellfish poisoning, coral reef destruction, and other harmful outcomes. All U.S. coasts show signs of nutrient over-enrichment, and scientists predict worsening problems in the years ahead. Clean Coastal Waters explains technical aspects of nutrient over-enrichment and proposes both immediate local action by coastal managers and a longer-term national strategy incorporating policy design, classification of affected sites, law and regulation, coordination, and communication. Highlighting the Gulf of Mexico's "Dead Zone," the Pfiesteria outbreak in a tributary of Chesapeake Bay, and other cases, the book explains how nutrients work in the environment, why nitrogen is important, how enrichment turns into over-enrichment, and why some environments are especially susceptible. Economic as well as ecological impacts are examined. In addressing abatement strategies, the committee discusses the importance of monitoring sites, developing useful models of over-enrichment, and setting water quality goals. The book also reviews voluntary programs, mandatory controls, tax incentives, and other policy options for reducing the flow of nutrients from agricultural operations and other sources.