Leon Kauffman
Leon Kauffman is a scientist working remotely with the New Jersey Water Science Center Integrated Hydrology Investigation Team
Science and Products
Filter Total Items: 25
Aquifer framework datasets used to represent the Pecos River Basin alluvial aquifer, Texas, New Mexico Aquifer framework datasets used to represent the Pecos River Basin alluvial aquifer, Texas, New Mexico
The Pecos River Basin alluvial aquifer, hereinafter referred to as the "Pecos aquifer", is located in western Texas and southeastern New Mexico. The aquifer is primarily composed of alluvial sand and gravel deposits mantled by sand and silt. The Pecos aquifer overlies Permian, Triassic, and Cretaceous-age rocks. The saturated thickness of the aquifer ranges from 0 to 1000 feet. The...
MODFLOW-2005 model used to analyze water-use scenarios in the New Jersey Coastal Plain MODFLOW-2005 model used to analyze water-use scenarios in the New Jersey Coastal Plain
Three withdrawal scenarios spanning from 2014 through 2040 were simulated using a previously published three-dimensional groundwater flow model of the New Jersey Coastal Plain (NJCP) (Gordon and Carleton, 2023). This model, run in MODFLOW-2005 (version 1.12.00), was recently updated by the U.S. Geological Survey (USGS) ensuring the models continued relevance for water-resource management...
Histogram-based gradient boosted regression tree model of mean ages of shallow well samples in the Great Lakes Basin, USA Histogram-based gradient boosted regression tree model of mean ages of shallow well samples in the Great Lakes Basin, USA
Green and others (2021) developed a gradient boosted regression tree model to predict the mean groundwater age, or travel time, for shallow wells across a portion of the Great Lakes basin in the United States. Their study applied machine learning methods to predict ages in wells using well construction, well chemistry, and landscape characteristics. For a dataset of age tracers in 961...
Python-HBRT model and groundwater levels used for estimating the static, shallow water table depth for the State of Wisconsin Python-HBRT model and groundwater levels used for estimating the static, shallow water table depth for the State of Wisconsin
A histrogram-based boosted regression tree (HBRT) method was used to predict the depth to the surficial aquifer water table (in feet) throughout the State of Wisconsin. This method used a combination of discrete groundwater levels from the U.S. Geological Survey National Water Information System, continuous groundwater levels from the National Groundwater Monitoring Network, the State of...
Data for Machine Learning Predictions of Nitrate in Shallow Groundwater in the Conterminous United States Data for Machine Learning Predictions of Nitrate in Shallow Groundwater in the Conterminous United States
An extreme gradient boosting (XGB) machine learning model was developed to predict the distribution of nitrate in shallow groundwater across the conterminous United States (CONUS). Nitrate was predicted at a 1-square-kilometer (km) resolution at a depth below the water table of 10 m. The model builds off a previous XGB machine learning model developed to predict nitrate at domestic and...
MODPATH-NWT and MODPATH6 models used to compare a new general simulation model approach with a conventional inset model approach for groundwater residence time in glacial aquifers MODPATH-NWT and MODPATH6 models used to compare a new general simulation model approach with a conventional inset model approach for groundwater residence time in glacial aquifers
This groundwater-flow model archive/data release contains the model input and output files for 1) edited versions of four of the five NAWQA steady- state, inset MODFLOW-NWT models of regional model of Lake Michigan Basin (https://doi.org/10.3133/sir20185038) and 2) general models simulating the same four basins as the four inset models. Two HUC8 basins in the lower peninsula of Michigan...
Data for depth of groundwater used for drinking-water supplies in the United States (ver. 2.0, January 2026) Data for depth of groundwater used for drinking-water supplies in the United States (ver. 2.0, January 2026)
This data release includes grids representing the depth and thickness of drinking-water withdrawal zones, polygons of hydrogeologic settings, an inventory of sources of well construction data, and summaries of data comparisons used to assess the depth of groundwater used for drinking-water supplies in the United States. Well construction data sources are documented in Table1_DataSources...
Estimated equivalent population using groundwater for public supply domestic use in the conterminous U.S. 2010, hydrogeologic mapping units, and wells used (ver. 2.0, March 2023) Estimated equivalent population using groundwater for public supply domestic use in the conterminous U.S. 2010, hydrogeologic mapping units, and wells used (ver. 2.0, March 2023)
These datasets map the estimated population using public supply drinking water (both groundwater and surface water) using two methods: the census enhanced method (CEM) evenly distributes the population across populated census blocks, and the urban land-use enhanced method (ULUEM) distributes the population only to certain urban land use designations. (See the six Estimated equivalent...
Data for Three-dimensional distribution of groundwater residence time metrics in the glaciated United States using metamodels trained on general numerical simulation models Data for Three-dimensional distribution of groundwater residence time metrics in the glaciated United States using metamodels trained on general numerical simulation models
Residence time distribution (RTD) is a critically important characteristic of groundwater flow systems; however, it cannot be measured directly. RTD can be inferred from tracer data with analytical models (few parameters) or with numerical models (many parameters). The second approach permits more variation in system properties but is used less frequently than the first because large...
Data used to evaluate drinking water quality in the glacial aquifer system, northern USA Data used to evaluate drinking water quality in the glacial aquifer system, northern USA
This data release contains groundwater-quality data and well information for the glacial aquifer system in the northern USA. Water-quality data and well information were derived from a dataset compiled from three sources: The U.S. Geological Survey (USGS) National Water Information System (NWIS; USGS, 1998, 2002), the U.S. Environmental Protection Agency (USEPA) Safe Drinking Water...
Data and Scripts for Metamodeling for Groundwater Age Forecasting in the Lake Michigan Basin Data and Scripts for Metamodeling for Groundwater Age Forecasting in the Lake Michigan Basin
Groundwater age is an important indicator of groundwater susceptibility to anthropogenic contamination and a key input to statistical models for forecasting water quality. Numerical models can provide estimates of groundwater age, enabling interpretation of measured age tracers. However, to extend to national-scale groundwater systems where numerical models are not routinely available, a...
Digital products from a hydrogeologic framework for Quaternary sediments within the glaciated conterminous United States Digital products from a hydrogeologic framework for Quaternary sediments within the glaciated conterminous United States
This data release is a compilation of the digital products from a hydrogeologic framework of the glaciated conterminous United States that were constructed to portray sediment and aquifer characteristics within this area. These digital products are described in Yager, R.M., Kauffman, L.J., Soller, D.R., Haj, A.E., Heisig, P.M., Buchwald, C.A., Westenbroek, S.M., and Reddy, J.E., 2018
Filter Total Items: 41
A partial exponential lumped parameter model to evaluate groundwater age distributions and nitrate trends in long-screened wells A partial exponential lumped parameter model to evaluate groundwater age distributions and nitrate trends in long-screened wells
A partial exponential lumped parameter model (PEM) was derived to determine age distributions and nitrate trends in long-screened production wells. The PEM can simulate age distributions for wells screened over any finite interval of an aquifer that has an exponential distribution of age with depth. The PEM has 3 parameters – the ratio of saturated thickness to the top and bottom of the...
Authors
Bryant C. Jurgens, John Karl Bohlke, Leon J. Kauffman, Kenneth Belitz, Bradley K. Esser
Modeling long-term trends of chlorinated ethene contamination at a public supply well Modeling long-term trends of chlorinated ethene contamination at a public supply well
A mass-balance solute-transport modeling approach was used to investigate the effects of dense nonaqueous phase liquid (DNAPL) volume, composition, and generation of daughter products on simulated and measured long-term trends of chlorinated ethene (CE) concentrations at a public supply well. The model was built by telescoping a calibrated regional three-dimensional MODFLOW model to the...
Authors
Francis H. Chapelle, Leon J. Kauffman, Mark A. Widdowson
Comparison of age distributions estimated from environmental tracers by using binary-dilution and numerical models of fractured and folded karst: Shenandoah Valley of Virginia and West Virginia, USA Comparison of age distributions estimated from environmental tracers by using binary-dilution and numerical models of fractured and folded karst: Shenandoah Valley of Virginia and West Virginia, USA
Measured concentrations of environmental tracers in spring discharge from a karst aquifer in the Shenandoah Valley, USA, were used to refine a numerical groundwater flow model. The karst aquifer is folded and faulted carbonate bedrock dominated by diffuse flow along fractures. The numerical model represented bedrock structure and discrete features (fault zones and springs)...
Authors
Richard M. Yager, Niel Plummer, Leon J. Kauffman, Daniel H. Doctor, David L. Nelms, Peter Schlosser
Modeling the effects of naturally occurring organic carbon on chlorinated ethene transport to a public supply well Modeling the effects of naturally occurring organic carbon on chlorinated ethene transport to a public supply well
The vulnerability of public supply wells to chlorinated ethene (CE) contamination in part depends on the availability of naturally occurring organic carbon to consume dissolved oxygen (DO) and initiate reductive dechlorination. This was quantified by building a mass balance model of the Kirkwood-Cohansey aquifer, which is widely used for public water supply in New Jersey. This model was...
Authors
Francis H. Chapelle, Leon J. Kauffman, Mark A. Widdowson
A zonal evaluation of intrinsic susceptibility in selected principal aquifers of the United States A zonal evaluation of intrinsic susceptibility in selected principal aquifers of the United States
A method was developed to evaluate intrinsic groundwater susceptibility in 11 study areas across the United States. Calibrated groundwater-flow models and a variable-advection particle-tracking scheme that accounts for uncertainty were used to derive ranges of conservative solute concentration and groundwater age within spatially defined zones from solute loading to the water table...
Authors
Tristan P. Wellman, Leon Kauffman, Brian Clark
Comparison of particle-tracking and lumped-parameter age-distribution models for evaluating vulnerability of production wells to contamination Comparison of particle-tracking and lumped-parameter age-distribution models for evaluating vulnerability of production wells to contamination
Environmental age tracers have been used in various ways to help assess vulnerability of drinking-water production wells to contamination. The most appropriate approach will depend on the information that is available and that which is desired. To understand how the well will respond to changing nonpoint-source contaminant inputs at the water table, some representation of the...
Authors
S. M. Eberts, J.K. Böhlke, L. J. Kauffman, B.C. Jurgens
On modeling weak sinks in MODPATH On modeling weak sinks in MODPATH
Regional groundwater flow systems often contain both strong sinks and weak sinks. A strong sink extracts water from the entire aquifer depth, while a weak sink lets some water pass underneath or over the actual sink. The numerical groundwater flow model MODFLOW may allow a sink cell to act as a strong or weak sink, hence extracting all water that enters the cell or allowing some of that...
Authors
Daniel B. Abrams, Henk Haitjema, Leon J. Kauffman
Modeling the potential impact of seasonal and inactive multi-aquifer wells on contaminant movement to public water-supply wells Modeling the potential impact of seasonal and inactive multi-aquifer wells on contaminant movement to public water-supply wells
Wells screened across multiple aquifers can provide pathways for the movement of surprisingly large volumes of groundwater to confined aquifers used for public water supply (PWS). Using a simple numerical model, we examine the impact of several pumping scenarios on leakage from an unconfined aquifer to a confined aquifer and conclude that a single inactive multi-aquifer well can...
Authors
R.L. Johnson, B.R. Clark, M.K. Landon, L. J. Kauffman, S. M. Eberts
Simulations of groundwater flow and particle-tracking analysis in the zone of contribution to a public-supply well in San Antonio, Texas Simulations of groundwater flow and particle-tracking analysis in the zone of contribution to a public-supply well in San Antonio, Texas
In 2006, a public-supply well in San Antonio, Texas, was selected for intensive study to assess the vulnerability of public-supply wells in the Edwards aquifer to contamination by a variety of compounds. A local-scale, steady-state, three-dimensional numerical groundwater-flow model was developed and used in this study to evaluate the movement of water and solutes from recharge areas to...
Authors
Richard L. Lindgren, Natalie A. Houston, MaryLynn Musgrove, Lynne S. Fahlquist, Leon J. Kauffman
Using Cl/Br ratios and other indicators to assess potential impacts on groundwater quality from septic systems: A review and examples from principal aquifers in the United States Using Cl/Br ratios and other indicators to assess potential impacts on groundwater quality from septic systems: A review and examples from principal aquifers in the United States
A detailed review was made of chemical indicators used to identify impacts from septic tanks on groundwater quality. Potential impacts from septic tank leachate on groundwater quality were assessed using the mass ratio of chloride–bromide (Cl/Br), concentrations of selected chemical constituents, and ancillary information (land use, census data, well depth, soil characteristics) for...
Authors
B. G. Katz, S. M. Eberts, L. J. Kauffman
Relative vulnerability of public supply wells to VOC contamination in hydrologically distinct regional aquifers Relative vulnerability of public supply wells to VOC contamination in hydrologically distinct regional aquifers
A process-based methodology was used to compare the vulnerability of public supply wells tapping seven study areas in four hydrologically distinct regional aquifers to volatile organic compound (VOC) contamination. This method considers (1) contributing areas and travel times of groundwater flowpaths converging at individual supply wells, (2) the oxic and/or anoxic conditions encountered...
Authors
Leon J. Kauffman, Francis H. Chapelle
Simulations of Groundwater Flow and Particle Tracking Analysis in the Area Contributing Recharge to a Public-Supply Well near Tampa, Florida, 2002-05 Simulations of Groundwater Flow and Particle Tracking Analysis in the Area Contributing Recharge to a Public-Supply Well near Tampa, Florida, 2002-05
Shallow ground water in the north-central Tampa Bay region, Florida, is affected by elevated nitrate concentrations, the presence of volatile organic compounds, and pesticides as a result of groundwater development and intensive urban land use. The region relies primarily on groundwater for drinking-water supplies. Sustainability of groundwater quality for public supply requires...
Authors
Christy A. Crandall, Leon J. Kauffman, Brian G. Katz, Patricia A. Metz, W. Scott McBride, Marian P. Berndt
Science and Products
Filter Total Items: 25
Aquifer framework datasets used to represent the Pecos River Basin alluvial aquifer, Texas, New Mexico Aquifer framework datasets used to represent the Pecos River Basin alluvial aquifer, Texas, New Mexico
The Pecos River Basin alluvial aquifer, hereinafter referred to as the "Pecos aquifer", is located in western Texas and southeastern New Mexico. The aquifer is primarily composed of alluvial sand and gravel deposits mantled by sand and silt. The Pecos aquifer overlies Permian, Triassic, and Cretaceous-age rocks. The saturated thickness of the aquifer ranges from 0 to 1000 feet. The...
MODFLOW-2005 model used to analyze water-use scenarios in the New Jersey Coastal Plain MODFLOW-2005 model used to analyze water-use scenarios in the New Jersey Coastal Plain
Three withdrawal scenarios spanning from 2014 through 2040 were simulated using a previously published three-dimensional groundwater flow model of the New Jersey Coastal Plain (NJCP) (Gordon and Carleton, 2023). This model, run in MODFLOW-2005 (version 1.12.00), was recently updated by the U.S. Geological Survey (USGS) ensuring the models continued relevance for water-resource management...
Histogram-based gradient boosted regression tree model of mean ages of shallow well samples in the Great Lakes Basin, USA Histogram-based gradient boosted regression tree model of mean ages of shallow well samples in the Great Lakes Basin, USA
Green and others (2021) developed a gradient boosted regression tree model to predict the mean groundwater age, or travel time, for shallow wells across a portion of the Great Lakes basin in the United States. Their study applied machine learning methods to predict ages in wells using well construction, well chemistry, and landscape characteristics. For a dataset of age tracers in 961...
Python-HBRT model and groundwater levels used for estimating the static, shallow water table depth for the State of Wisconsin Python-HBRT model and groundwater levels used for estimating the static, shallow water table depth for the State of Wisconsin
A histrogram-based boosted regression tree (HBRT) method was used to predict the depth to the surficial aquifer water table (in feet) throughout the State of Wisconsin. This method used a combination of discrete groundwater levels from the U.S. Geological Survey National Water Information System, continuous groundwater levels from the National Groundwater Monitoring Network, the State of...
Data for Machine Learning Predictions of Nitrate in Shallow Groundwater in the Conterminous United States Data for Machine Learning Predictions of Nitrate in Shallow Groundwater in the Conterminous United States
An extreme gradient boosting (XGB) machine learning model was developed to predict the distribution of nitrate in shallow groundwater across the conterminous United States (CONUS). Nitrate was predicted at a 1-square-kilometer (km) resolution at a depth below the water table of 10 m. The model builds off a previous XGB machine learning model developed to predict nitrate at domestic and...
MODPATH-NWT and MODPATH6 models used to compare a new general simulation model approach with a conventional inset model approach for groundwater residence time in glacial aquifers MODPATH-NWT and MODPATH6 models used to compare a new general simulation model approach with a conventional inset model approach for groundwater residence time in glacial aquifers
This groundwater-flow model archive/data release contains the model input and output files for 1) edited versions of four of the five NAWQA steady- state, inset MODFLOW-NWT models of regional model of Lake Michigan Basin (https://doi.org/10.3133/sir20185038) and 2) general models simulating the same four basins as the four inset models. Two HUC8 basins in the lower peninsula of Michigan...
Data for depth of groundwater used for drinking-water supplies in the United States (ver. 2.0, January 2026) Data for depth of groundwater used for drinking-water supplies in the United States (ver. 2.0, January 2026)
This data release includes grids representing the depth and thickness of drinking-water withdrawal zones, polygons of hydrogeologic settings, an inventory of sources of well construction data, and summaries of data comparisons used to assess the depth of groundwater used for drinking-water supplies in the United States. Well construction data sources are documented in Table1_DataSources...
Estimated equivalent population using groundwater for public supply domestic use in the conterminous U.S. 2010, hydrogeologic mapping units, and wells used (ver. 2.0, March 2023) Estimated equivalent population using groundwater for public supply domestic use in the conterminous U.S. 2010, hydrogeologic mapping units, and wells used (ver. 2.0, March 2023)
These datasets map the estimated population using public supply drinking water (both groundwater and surface water) using two methods: the census enhanced method (CEM) evenly distributes the population across populated census blocks, and the urban land-use enhanced method (ULUEM) distributes the population only to certain urban land use designations. (See the six Estimated equivalent...
Data for Three-dimensional distribution of groundwater residence time metrics in the glaciated United States using metamodels trained on general numerical simulation models Data for Three-dimensional distribution of groundwater residence time metrics in the glaciated United States using metamodels trained on general numerical simulation models
Residence time distribution (RTD) is a critically important characteristic of groundwater flow systems; however, it cannot be measured directly. RTD can be inferred from tracer data with analytical models (few parameters) or with numerical models (many parameters). The second approach permits more variation in system properties but is used less frequently than the first because large...
Data used to evaluate drinking water quality in the glacial aquifer system, northern USA Data used to evaluate drinking water quality in the glacial aquifer system, northern USA
This data release contains groundwater-quality data and well information for the glacial aquifer system in the northern USA. Water-quality data and well information were derived from a dataset compiled from three sources: The U.S. Geological Survey (USGS) National Water Information System (NWIS; USGS, 1998, 2002), the U.S. Environmental Protection Agency (USEPA) Safe Drinking Water...
Data and Scripts for Metamodeling for Groundwater Age Forecasting in the Lake Michigan Basin Data and Scripts for Metamodeling for Groundwater Age Forecasting in the Lake Michigan Basin
Groundwater age is an important indicator of groundwater susceptibility to anthropogenic contamination and a key input to statistical models for forecasting water quality. Numerical models can provide estimates of groundwater age, enabling interpretation of measured age tracers. However, to extend to national-scale groundwater systems where numerical models are not routinely available, a...
Digital products from a hydrogeologic framework for Quaternary sediments within the glaciated conterminous United States Digital products from a hydrogeologic framework for Quaternary sediments within the glaciated conterminous United States
This data release is a compilation of the digital products from a hydrogeologic framework of the glaciated conterminous United States that were constructed to portray sediment and aquifer characteristics within this area. These digital products are described in Yager, R.M., Kauffman, L.J., Soller, D.R., Haj, A.E., Heisig, P.M., Buchwald, C.A., Westenbroek, S.M., and Reddy, J.E., 2018
Filter Total Items: 41
A partial exponential lumped parameter model to evaluate groundwater age distributions and nitrate trends in long-screened wells A partial exponential lumped parameter model to evaluate groundwater age distributions and nitrate trends in long-screened wells
A partial exponential lumped parameter model (PEM) was derived to determine age distributions and nitrate trends in long-screened production wells. The PEM can simulate age distributions for wells screened over any finite interval of an aquifer that has an exponential distribution of age with depth. The PEM has 3 parameters – the ratio of saturated thickness to the top and bottom of the...
Authors
Bryant C. Jurgens, John Karl Bohlke, Leon J. Kauffman, Kenneth Belitz, Bradley K. Esser
Modeling long-term trends of chlorinated ethene contamination at a public supply well Modeling long-term trends of chlorinated ethene contamination at a public supply well
A mass-balance solute-transport modeling approach was used to investigate the effects of dense nonaqueous phase liquid (DNAPL) volume, composition, and generation of daughter products on simulated and measured long-term trends of chlorinated ethene (CE) concentrations at a public supply well. The model was built by telescoping a calibrated regional three-dimensional MODFLOW model to the...
Authors
Francis H. Chapelle, Leon J. Kauffman, Mark A. Widdowson
Comparison of age distributions estimated from environmental tracers by using binary-dilution and numerical models of fractured and folded karst: Shenandoah Valley of Virginia and West Virginia, USA Comparison of age distributions estimated from environmental tracers by using binary-dilution and numerical models of fractured and folded karst: Shenandoah Valley of Virginia and West Virginia, USA
Measured concentrations of environmental tracers in spring discharge from a karst aquifer in the Shenandoah Valley, USA, were used to refine a numerical groundwater flow model. The karst aquifer is folded and faulted carbonate bedrock dominated by diffuse flow along fractures. The numerical model represented bedrock structure and discrete features (fault zones and springs)...
Authors
Richard M. Yager, Niel Plummer, Leon J. Kauffman, Daniel H. Doctor, David L. Nelms, Peter Schlosser
Modeling the effects of naturally occurring organic carbon on chlorinated ethene transport to a public supply well Modeling the effects of naturally occurring organic carbon on chlorinated ethene transport to a public supply well
The vulnerability of public supply wells to chlorinated ethene (CE) contamination in part depends on the availability of naturally occurring organic carbon to consume dissolved oxygen (DO) and initiate reductive dechlorination. This was quantified by building a mass balance model of the Kirkwood-Cohansey aquifer, which is widely used for public water supply in New Jersey. This model was...
Authors
Francis H. Chapelle, Leon J. Kauffman, Mark A. Widdowson
A zonal evaluation of intrinsic susceptibility in selected principal aquifers of the United States A zonal evaluation of intrinsic susceptibility in selected principal aquifers of the United States
A method was developed to evaluate intrinsic groundwater susceptibility in 11 study areas across the United States. Calibrated groundwater-flow models and a variable-advection particle-tracking scheme that accounts for uncertainty were used to derive ranges of conservative solute concentration and groundwater age within spatially defined zones from solute loading to the water table...
Authors
Tristan P. Wellman, Leon Kauffman, Brian Clark
Comparison of particle-tracking and lumped-parameter age-distribution models for evaluating vulnerability of production wells to contamination Comparison of particle-tracking and lumped-parameter age-distribution models for evaluating vulnerability of production wells to contamination
Environmental age tracers have been used in various ways to help assess vulnerability of drinking-water production wells to contamination. The most appropriate approach will depend on the information that is available and that which is desired. To understand how the well will respond to changing nonpoint-source contaminant inputs at the water table, some representation of the...
Authors
S. M. Eberts, J.K. Böhlke, L. J. Kauffman, B.C. Jurgens
On modeling weak sinks in MODPATH On modeling weak sinks in MODPATH
Regional groundwater flow systems often contain both strong sinks and weak sinks. A strong sink extracts water from the entire aquifer depth, while a weak sink lets some water pass underneath or over the actual sink. The numerical groundwater flow model MODFLOW may allow a sink cell to act as a strong or weak sink, hence extracting all water that enters the cell or allowing some of that...
Authors
Daniel B. Abrams, Henk Haitjema, Leon J. Kauffman
Modeling the potential impact of seasonal and inactive multi-aquifer wells on contaminant movement to public water-supply wells Modeling the potential impact of seasonal and inactive multi-aquifer wells on contaminant movement to public water-supply wells
Wells screened across multiple aquifers can provide pathways for the movement of surprisingly large volumes of groundwater to confined aquifers used for public water supply (PWS). Using a simple numerical model, we examine the impact of several pumping scenarios on leakage from an unconfined aquifer to a confined aquifer and conclude that a single inactive multi-aquifer well can...
Authors
R.L. Johnson, B.R. Clark, M.K. Landon, L. J. Kauffman, S. M. Eberts
Simulations of groundwater flow and particle-tracking analysis in the zone of contribution to a public-supply well in San Antonio, Texas Simulations of groundwater flow and particle-tracking analysis in the zone of contribution to a public-supply well in San Antonio, Texas
In 2006, a public-supply well in San Antonio, Texas, was selected for intensive study to assess the vulnerability of public-supply wells in the Edwards aquifer to contamination by a variety of compounds. A local-scale, steady-state, three-dimensional numerical groundwater-flow model was developed and used in this study to evaluate the movement of water and solutes from recharge areas to...
Authors
Richard L. Lindgren, Natalie A. Houston, MaryLynn Musgrove, Lynne S. Fahlquist, Leon J. Kauffman
Using Cl/Br ratios and other indicators to assess potential impacts on groundwater quality from septic systems: A review and examples from principal aquifers in the United States Using Cl/Br ratios and other indicators to assess potential impacts on groundwater quality from septic systems: A review and examples from principal aquifers in the United States
A detailed review was made of chemical indicators used to identify impacts from septic tanks on groundwater quality. Potential impacts from septic tank leachate on groundwater quality were assessed using the mass ratio of chloride–bromide (Cl/Br), concentrations of selected chemical constituents, and ancillary information (land use, census data, well depth, soil characteristics) for...
Authors
B. G. Katz, S. M. Eberts, L. J. Kauffman
Relative vulnerability of public supply wells to VOC contamination in hydrologically distinct regional aquifers Relative vulnerability of public supply wells to VOC contamination in hydrologically distinct regional aquifers
A process-based methodology was used to compare the vulnerability of public supply wells tapping seven study areas in four hydrologically distinct regional aquifers to volatile organic compound (VOC) contamination. This method considers (1) contributing areas and travel times of groundwater flowpaths converging at individual supply wells, (2) the oxic and/or anoxic conditions encountered...
Authors
Leon J. Kauffman, Francis H. Chapelle
Simulations of Groundwater Flow and Particle Tracking Analysis in the Area Contributing Recharge to a Public-Supply Well near Tampa, Florida, 2002-05 Simulations of Groundwater Flow and Particle Tracking Analysis in the Area Contributing Recharge to a Public-Supply Well near Tampa, Florida, 2002-05
Shallow ground water in the north-central Tampa Bay region, Florida, is affected by elevated nitrate concentrations, the presence of volatile organic compounds, and pesticides as a result of groundwater development and intensive urban land use. The region relies primarily on groundwater for drinking-water supplies. Sustainability of groundwater quality for public supply requires...
Authors
Christy A. Crandall, Leon J. Kauffman, Brian G. Katz, Patricia A. Metz, W. Scott McBride, Marian P. Berndt