Gregory E Schwarz
Gregory Schwarz is an Economist with the USGS Water Resources Mission Area.
Science and Products
River Corridor hot spots for biogeochemical processing: a continental scale synthesis
Rivers are the veins of the landscape, providing environmental benefits that are disproportionately high relative to their aerial extent; shedding flood waters, hosting aquatic ecosystems, transporting solutes and energy-rich materials, and storing and transforming pollutants into less harmful forms. From uplands to the coasts, rivers facilitate key biogeochemical reactions that cumulatively influ
Illinois River basin seasonally dynamic total nitrogen and phosphorus SPARROW model inputs and outputs, 2000 through 2020
This data release contains seasonal source-specific estimates of total nitrogen (TN) and total phosphorus (TP) loading to streams across the Illinois River basin (25,620 reaches) for 21 years from 2000 through 2020 using a dynamic SPARROW (Spatially Referenced Regressions on Watershed attributes) model. Input data including calibration loads, output predictions, model control files, and model sour
Attributes for NHDPlus Version 2.1 Catchments and Modified Routing of Upstream Watersheds for the Conterminous United States: Riparian National Land Cover Data for 2019 Versions for the Years 2001, 2004, 2006, 2008, 2011, 2013, 2016, and 2019
This tabular data set represents the percent of land cover classes in the riparian zone from the 2019 edition of the National Land Cover databases for the years 2001, 2004, 2006, 2008, 2011, 2013, 2016 and 2019 compiled for two spatial components of the NHDPlus version 2.1 data suite (NHDPlusv2) for the conterminous United States; 1) individual reach catchments and 2) reach catchments accumulated
Model code, input datasets, and prediction files for dynamic stream dissolved solids and static baseflow dissolved solids SPARROW models of the Upper Colorado River Basin, 1986-2017
This data release contains model code and input data for, and predictions from, both a dynamic stream dissolved solids and a static baseflow dissolved solids SPARROW (SPAtially Referenced Regression On Watershed attributes) model of the Upper Colorado River Basin for water years 1986-2017. Input data includes information on dissolved solids sources, landscape transport characteristics, and dissolv
Mean seasonal SPARROW model inputs and simulated nitrogen and phosphorus loads for the Northeastern United States 2002 base year
This U.S. Geological Survey (USGS) data release includes input and output tabular files associated with mean seasonal 2002 simulations of total nitrogen and total phosphorus loads of the northeastern United States. The mean seasonal (MS) simulations are performed using a dynamic configuration of the USGS's Spatially Referenced Regression On Watershed attributes (dynamicSPARROW-MS) model, nonlinear
Nutrient Load Data used to Quantify Regional Effects of Agricultural Best Management Practices: An application of the 2012 SPARROW models for the Midwest, Northeast, and Southeast United States
Nitrogen and phosphorus losses from agricultural areas have impacted the water quality of downstream rivers, lakes, and oceans. As a result, investment in the adoption of agricultural best management practices (BMPs) has grown but assessments of their effectiveness at large spatial scales have been sparse. This study applies regional Spatially Referenced Regression On Watershed-attributes (SPARROW
Iron fouling data associated with drainage from roadway sites constructed with rock fill in New Hampshire
This data release contains files that are associated with the publication 'Understanding and predicting iron fouling associated with drainage from roadway sites constructed with rock-fill in New Hampshire, USA'. Each zipped file contains a data table or raster file and an associated metadata file. IronFoulingCutFillData.zip contains a .csv file and .xml metadata file related to the roadcut and roc
Select Attributes for NHDPlus Version 2.1 Reach Catchments and Modified Network Routed Upstream Watersheds for the Conterminous United States (ver. 4.0, August 2023)
This metadata record describes a series of data sets of natural and anthropogenic landscape features linked to NHDPlus Version 2.1's (NHDPlusV2) approximately 2.7 million stream segments, their associated catchments, and their upstream watersheds within the conterminous United States. These data were developed by the Hydrologic Sytem's Team (HST) within the the United States Geological Survey's (
Water-quality and streamflow datasets used for estimating long-term mean daily streamflow and annual loads to be considered for use in regional streamflow, nutrient and sediment SPARROW models, United States, 1999-2014
The United States Geological Survey's (USGS) SPAtially Referenced Regressions On Watershed attributes (SPARROW) model was developed to aid in the interpretation of monitoring data and simulate water-quality conditions in streams across large spatial scales. SPARROW is a hybrid empirical/process-based mass balance model that can be used to estimate the major sources and environmental factors that a
Inputs and Selected Predictions of the CBTN_v5 and CBTP_v5 SPARROW Models for the Chesapeake Bay Watershed
The CBTN_v5 and CBTP_v5 SPARROW models were developed to support inferences about causes of observed changes in nitrogen and phosphorus (respectively) fluxes in Chesapeake Bay tributaries between 1992 and 2012. Model inputs and outputs are included in three files, which are described below. Detailed documentation of the SPARROW modeling technique is available at https://pubs.er.usgs.gov/publicatio
Database of modified routing for NHDPlus version 2.1 flowlines: ENHDPlusV2_us
This database (ENHDPlusV2_us) contains a topologically reconditioned (enhanced) version of the U.S. Environmental Protection Agency (USEPA) and the U.S. Geological Survey (USGS) NHDPlus Version 2.1 (NHDPlusV2) flowline network. The comma separated file included in this release contains routing and stream connection information, with the intention of improving accuracy and networking capabilities.
Filter Total Items: 67
Seasonally varying contributions of contemporaneous and lagged sources of instream total nitrogen and phosphorus load across the Illinois River basin
Quantifying nutrient sources in streams, their temporal and spatial variability, and drivers of that variability can support effective water resources management. Yet a lack of data and modeling capabilities has previously prevented comprehensive quantification across both space and time. Here a dynamic SPARROW (Spatially Referenced Regressions on Watershed attributes) model that accounts for a la
Authors
Noah Schmadel, Olivia L. Miller, Scott Ator, Matthew P. Miller, Gregory E. Schwarz, Dale M. Robertson, Andrew Sekellick, Kenneth Skinner, David A. Saad
Temporal variability in irrigated land and climate influences on salinity loading across the Upper Colorado River Basin, 1986-2017
Freshwater salinization is a growing global concern impacting human and ecosystem needs with impacts to water availability for human and ecological uses. In the Upper Colorado River Basin (UCRB), dissolved solids in streams compound ongoing water supply challenges to further limit water availability and cause economic damages. Much effort has been dedicated to understanding dissolved solid sources
Authors
Olivia L. Miller, Annie L. Putman, Richard A. Smith, Gregory E. Schwarz, Michael D. Hess, Morgan C. McDonnell, Daniel Jones
Sand- and gravel-trapping efficiencies derived for four types of pressure-difference bedload samplers
Bedload-trapping efficiencies (coefficients) were derived for four types of pressure-difference bedload samplers at the St. Anthony Falls Laboratory, University of Minnesota during the first two phases of flume experiments in January-March, 2006, referred to as “StreamLab06.” The bedload-sampler research component was part of a series of community-led, large-scale laboratory experiments performed
Authors
John Gray, Joel T. Groten, Jonathan A. Czuba, Gregory E. Schwarz, Kyle Strom, Panayiotis Diplas
Predicting near-term effects of climate change on nitrogen transport to Chesapeake Bay
Understanding effects of climate change on nitrogen fate and transport in the environment is critical to nutrient management. We used climate projections within a previously calibrated spatially referenced regression (SPARROW) model to predict effects of expected climate change over 1995 through 2025 on total nitrogen fluxes to Chesapeake Bay and in watershed streams. Assuming nitrogen inputs and
Authors
Scott Ator, Gregory E. Schwarz, Andrew Sekellick, Gopal Bhatt
Quantifying regional effects of best management practices on nutrient losses from agricultural lands
Nitrogen (N) and phosphorus (P) losses from agricultural areas have degraded the water quality of downstream rivers, lakes, and oceans. As a result, investment in the adoption of agricultural best management practices (BMPs) has grown, but assessments of their effectiveness at large spatial scales have lagged. This study applies regional Spatially Referenced Regression On Watershed-attributes (SPA
Authors
Victor L. Roland, Ana María García, David A. Saad, Scott W. Ator, Dale M. Robertson, Gregory E. Schwarz
Seasonally dynamic nutrient modeling quantifies storage lags and time-varying reactivity across large river basins
Nutrients that have gradually accumulated in soils, groundwaters, and river sediments in the United States over the past century can remobilize and increase current downstream loading, obscuring effects of conservation practices aimed at protecting water resources. Drivers of storage accumulation and release of nutrients are poorly understood at the spatial scale of basins to watersheds. Predictin
Authors
Noah Schmadel, Judson Harvey, Gregory E. Schwarz
Instruments, methods, rationale, and derived data used to quantify and compare the trapping efficiencies of four types of pressure-difference bedload samplers
Bedload and ancillary data were collected to calculate and compare the bedload trapping efficiencies of four types of pressure-difference bedload samplers as part of episodic, sediment-recirculating flume experiments at the St. Anthony Falls Laboratory, University of Minnesota, Minneapolis, in January–March 2006. The bedload-sampler experiments, which were conceived, organized, and led by the U.S.
Authors
John R. Gray, Gregory E. Schwarz, David Dean, Jonathan A. Czuba, Joel T. Groten
Accounting for temporal variability of streamflow in estimates of travel time
Retention, processing, and transport of solutes and particulates in stream corridors are influenced by the travel time of streamflow through stream channels, which varies dynamically with discharge. The effects of streamflow variability across sites and over time cannot be addressed by time-averaged models if parameters are based solely on the characteristics of mean streamflow. We develop methods
Authors
Christopher P. Konrad, Noah Schmadel, Judson Harvey, Gregory E. Schwarz, Jesus Gomez-Velez, Elizabeth W. Boyer, Durelle Scott
Low threshold for nitrogen concentration saturation in headwaters increases regional and coastal delivery
River corridors store, convey, and process nutrients from terrestrial and upstream sources, regulating delivery from headwaters to estuaries. A consequence of chronic excess nitrogen loading, as supported by theory and field studies in specific areas, is saturation of the biogeochemically-mediated nitrogen removal processes that weakens the capacity of the river corridor to remove nitrogen. Region
Authors
Noah Schmadel, Judson Harvey, Richard Alexander, Elizabeth W. Boyer, Gregory E. Schwarz, Jesus D. Gomez-Velez, Durelle Scott, Christopher Konrad
An enhanced hydrologic stream network based on the NHDPlus medium resolution dataset
The National Hydrography Dataset Plus, Version 2.1 (NHDPlusV2.1) is an attribute-rich digital stream network for the conterminous United States, serving as a foundational infrastructure for reporting hydrologic information at both regional and national scales. SPAtially Referenced Regressions On Watershed attributes (SPARROW) is a process-based statistical model that relies on a digital hydrologic
Authors
John W. Brakebill, Gregory E. Schwarz, Michael E. Wieczorek
Advances in quantifying streamflow variability across continental scales: 2. Improved model regionalization and prediction uncertainties using hierarchical Bayesian methods
The precise estimation of process effects in hydrological models requires applying models to large scales with extensive spatial variability in controlling factors. Despite progress in large‐scale applications of hydrological models in conterminous United States (CONUS) river basins, spatial constraints in model parameters have prevented the interbasin sharing of data, complicating quantification
Authors
Richard B. Alexander, Gregory E. Schwarz, Elizabeth W. Boyer
Phosphorus and nitrogen transport in the binational Great Lakes Basin estimated using SPARROW watershed models
Eutrophication problems in the Great Lakes are caused by excessive nutrient inputs (primarily phosphorus, P, and nitrogen, N) from various sources throughout its basin. In developing protection and restoration plans, it is important to know where and from what sources the nutrients originate. As part of a binational effort, Midcontinent SPARROW (SPAtially Referenced Regression On Watershed attribu
Authors
Dale M. Robertson, David A. Saad, Glenn A. Benoy, Ivana Vouk, Gregory E. Schwarz, Michael T Laitta
Science and Products
River Corridor hot spots for biogeochemical processing: a continental scale synthesis
Rivers are the veins of the landscape, providing environmental benefits that are disproportionately high relative to their aerial extent; shedding flood waters, hosting aquatic ecosystems, transporting solutes and energy-rich materials, and storing and transforming pollutants into less harmful forms. From uplands to the coasts, rivers facilitate key biogeochemical reactions that cumulatively influ
Illinois River basin seasonally dynamic total nitrogen and phosphorus SPARROW model inputs and outputs, 2000 through 2020
This data release contains seasonal source-specific estimates of total nitrogen (TN) and total phosphorus (TP) loading to streams across the Illinois River basin (25,620 reaches) for 21 years from 2000 through 2020 using a dynamic SPARROW (Spatially Referenced Regressions on Watershed attributes) model. Input data including calibration loads, output predictions, model control files, and model sour
Attributes for NHDPlus Version 2.1 Catchments and Modified Routing of Upstream Watersheds for the Conterminous United States: Riparian National Land Cover Data for 2019 Versions for the Years 2001, 2004, 2006, 2008, 2011, 2013, 2016, and 2019
This tabular data set represents the percent of land cover classes in the riparian zone from the 2019 edition of the National Land Cover databases for the years 2001, 2004, 2006, 2008, 2011, 2013, 2016 and 2019 compiled for two spatial components of the NHDPlus version 2.1 data suite (NHDPlusv2) for the conterminous United States; 1) individual reach catchments and 2) reach catchments accumulated
Model code, input datasets, and prediction files for dynamic stream dissolved solids and static baseflow dissolved solids SPARROW models of the Upper Colorado River Basin, 1986-2017
This data release contains model code and input data for, and predictions from, both a dynamic stream dissolved solids and a static baseflow dissolved solids SPARROW (SPAtially Referenced Regression On Watershed attributes) model of the Upper Colorado River Basin for water years 1986-2017. Input data includes information on dissolved solids sources, landscape transport characteristics, and dissolv
Mean seasonal SPARROW model inputs and simulated nitrogen and phosphorus loads for the Northeastern United States 2002 base year
This U.S. Geological Survey (USGS) data release includes input and output tabular files associated with mean seasonal 2002 simulations of total nitrogen and total phosphorus loads of the northeastern United States. The mean seasonal (MS) simulations are performed using a dynamic configuration of the USGS's Spatially Referenced Regression On Watershed attributes (dynamicSPARROW-MS) model, nonlinear
Nutrient Load Data used to Quantify Regional Effects of Agricultural Best Management Practices: An application of the 2012 SPARROW models for the Midwest, Northeast, and Southeast United States
Nitrogen and phosphorus losses from agricultural areas have impacted the water quality of downstream rivers, lakes, and oceans. As a result, investment in the adoption of agricultural best management practices (BMPs) has grown but assessments of their effectiveness at large spatial scales have been sparse. This study applies regional Spatially Referenced Regression On Watershed-attributes (SPARROW
Iron fouling data associated with drainage from roadway sites constructed with rock fill in New Hampshire
This data release contains files that are associated with the publication 'Understanding and predicting iron fouling associated with drainage from roadway sites constructed with rock-fill in New Hampshire, USA'. Each zipped file contains a data table or raster file and an associated metadata file. IronFoulingCutFillData.zip contains a .csv file and .xml metadata file related to the roadcut and roc
Select Attributes for NHDPlus Version 2.1 Reach Catchments and Modified Network Routed Upstream Watersheds for the Conterminous United States (ver. 4.0, August 2023)
This metadata record describes a series of data sets of natural and anthropogenic landscape features linked to NHDPlus Version 2.1's (NHDPlusV2) approximately 2.7 million stream segments, their associated catchments, and their upstream watersheds within the conterminous United States. These data were developed by the Hydrologic Sytem's Team (HST) within the the United States Geological Survey's (
Water-quality and streamflow datasets used for estimating long-term mean daily streamflow and annual loads to be considered for use in regional streamflow, nutrient and sediment SPARROW models, United States, 1999-2014
The United States Geological Survey's (USGS) SPAtially Referenced Regressions On Watershed attributes (SPARROW) model was developed to aid in the interpretation of monitoring data and simulate water-quality conditions in streams across large spatial scales. SPARROW is a hybrid empirical/process-based mass balance model that can be used to estimate the major sources and environmental factors that a
Inputs and Selected Predictions of the CBTN_v5 and CBTP_v5 SPARROW Models for the Chesapeake Bay Watershed
The CBTN_v5 and CBTP_v5 SPARROW models were developed to support inferences about causes of observed changes in nitrogen and phosphorus (respectively) fluxes in Chesapeake Bay tributaries between 1992 and 2012. Model inputs and outputs are included in three files, which are described below. Detailed documentation of the SPARROW modeling technique is available at https://pubs.er.usgs.gov/publicatio
Database of modified routing for NHDPlus version 2.1 flowlines: ENHDPlusV2_us
This database (ENHDPlusV2_us) contains a topologically reconditioned (enhanced) version of the U.S. Environmental Protection Agency (USEPA) and the U.S. Geological Survey (USGS) NHDPlus Version 2.1 (NHDPlusV2) flowline network. The comma separated file included in this release contains routing and stream connection information, with the intention of improving accuracy and networking capabilities.
Filter Total Items: 67
Seasonally varying contributions of contemporaneous and lagged sources of instream total nitrogen and phosphorus load across the Illinois River basin
Quantifying nutrient sources in streams, their temporal and spatial variability, and drivers of that variability can support effective water resources management. Yet a lack of data and modeling capabilities has previously prevented comprehensive quantification across both space and time. Here a dynamic SPARROW (Spatially Referenced Regressions on Watershed attributes) model that accounts for a la
Authors
Noah Schmadel, Olivia L. Miller, Scott Ator, Matthew P. Miller, Gregory E. Schwarz, Dale M. Robertson, Andrew Sekellick, Kenneth Skinner, David A. Saad
Temporal variability in irrigated land and climate influences on salinity loading across the Upper Colorado River Basin, 1986-2017
Freshwater salinization is a growing global concern impacting human and ecosystem needs with impacts to water availability for human and ecological uses. In the Upper Colorado River Basin (UCRB), dissolved solids in streams compound ongoing water supply challenges to further limit water availability and cause economic damages. Much effort has been dedicated to understanding dissolved solid sources
Authors
Olivia L. Miller, Annie L. Putman, Richard A. Smith, Gregory E. Schwarz, Michael D. Hess, Morgan C. McDonnell, Daniel Jones
Sand- and gravel-trapping efficiencies derived for four types of pressure-difference bedload samplers
Bedload-trapping efficiencies (coefficients) were derived for four types of pressure-difference bedload samplers at the St. Anthony Falls Laboratory, University of Minnesota during the first two phases of flume experiments in January-March, 2006, referred to as “StreamLab06.” The bedload-sampler research component was part of a series of community-led, large-scale laboratory experiments performed
Authors
John Gray, Joel T. Groten, Jonathan A. Czuba, Gregory E. Schwarz, Kyle Strom, Panayiotis Diplas
Predicting near-term effects of climate change on nitrogen transport to Chesapeake Bay
Understanding effects of climate change on nitrogen fate and transport in the environment is critical to nutrient management. We used climate projections within a previously calibrated spatially referenced regression (SPARROW) model to predict effects of expected climate change over 1995 through 2025 on total nitrogen fluxes to Chesapeake Bay and in watershed streams. Assuming nitrogen inputs and
Authors
Scott Ator, Gregory E. Schwarz, Andrew Sekellick, Gopal Bhatt
Quantifying regional effects of best management practices on nutrient losses from agricultural lands
Nitrogen (N) and phosphorus (P) losses from agricultural areas have degraded the water quality of downstream rivers, lakes, and oceans. As a result, investment in the adoption of agricultural best management practices (BMPs) has grown, but assessments of their effectiveness at large spatial scales have lagged. This study applies regional Spatially Referenced Regression On Watershed-attributes (SPA
Authors
Victor L. Roland, Ana María García, David A. Saad, Scott W. Ator, Dale M. Robertson, Gregory E. Schwarz
Seasonally dynamic nutrient modeling quantifies storage lags and time-varying reactivity across large river basins
Nutrients that have gradually accumulated in soils, groundwaters, and river sediments in the United States over the past century can remobilize and increase current downstream loading, obscuring effects of conservation practices aimed at protecting water resources. Drivers of storage accumulation and release of nutrients are poorly understood at the spatial scale of basins to watersheds. Predictin
Authors
Noah Schmadel, Judson Harvey, Gregory E. Schwarz
Instruments, methods, rationale, and derived data used to quantify and compare the trapping efficiencies of four types of pressure-difference bedload samplers
Bedload and ancillary data were collected to calculate and compare the bedload trapping efficiencies of four types of pressure-difference bedload samplers as part of episodic, sediment-recirculating flume experiments at the St. Anthony Falls Laboratory, University of Minnesota, Minneapolis, in January–March 2006. The bedload-sampler experiments, which were conceived, organized, and led by the U.S.
Authors
John R. Gray, Gregory E. Schwarz, David Dean, Jonathan A. Czuba, Joel T. Groten
Accounting for temporal variability of streamflow in estimates of travel time
Retention, processing, and transport of solutes and particulates in stream corridors are influenced by the travel time of streamflow through stream channels, which varies dynamically with discharge. The effects of streamflow variability across sites and over time cannot be addressed by time-averaged models if parameters are based solely on the characteristics of mean streamflow. We develop methods
Authors
Christopher P. Konrad, Noah Schmadel, Judson Harvey, Gregory E. Schwarz, Jesus Gomez-Velez, Elizabeth W. Boyer, Durelle Scott
Low threshold for nitrogen concentration saturation in headwaters increases regional and coastal delivery
River corridors store, convey, and process nutrients from terrestrial and upstream sources, regulating delivery from headwaters to estuaries. A consequence of chronic excess nitrogen loading, as supported by theory and field studies in specific areas, is saturation of the biogeochemically-mediated nitrogen removal processes that weakens the capacity of the river corridor to remove nitrogen. Region
Authors
Noah Schmadel, Judson Harvey, Richard Alexander, Elizabeth W. Boyer, Gregory E. Schwarz, Jesus D. Gomez-Velez, Durelle Scott, Christopher Konrad
An enhanced hydrologic stream network based on the NHDPlus medium resolution dataset
The National Hydrography Dataset Plus, Version 2.1 (NHDPlusV2.1) is an attribute-rich digital stream network for the conterminous United States, serving as a foundational infrastructure for reporting hydrologic information at both regional and national scales. SPAtially Referenced Regressions On Watershed attributes (SPARROW) is a process-based statistical model that relies on a digital hydrologic
Authors
John W. Brakebill, Gregory E. Schwarz, Michael E. Wieczorek
Advances in quantifying streamflow variability across continental scales: 2. Improved model regionalization and prediction uncertainties using hierarchical Bayesian methods
The precise estimation of process effects in hydrological models requires applying models to large scales with extensive spatial variability in controlling factors. Despite progress in large‐scale applications of hydrological models in conterminous United States (CONUS) river basins, spatial constraints in model parameters have prevented the interbasin sharing of data, complicating quantification
Authors
Richard B. Alexander, Gregory E. Schwarz, Elizabeth W. Boyer
Phosphorus and nitrogen transport in the binational Great Lakes Basin estimated using SPARROW watershed models
Eutrophication problems in the Great Lakes are caused by excessive nutrient inputs (primarily phosphorus, P, and nitrogen, N) from various sources throughout its basin. In developing protection and restoration plans, it is important to know where and from what sources the nutrients originate. As part of a binational effort, Midcontinent SPARROW (SPAtially Referenced Regression On Watershed attribu
Authors
Dale M. Robertson, David A. Saad, Glenn A. Benoy, Ivana Vouk, Gregory E. Schwarz, Michael T Laitta