Gregory E Schwarz (Former Employee)
Science and Products
Filter Total Items: 68
Small ponds in headwater catchments are a dominant influence on regional nutrient and sediment budgets Small ponds in headwater catchments are a dominant influence on regional nutrient and sediment budgets
Small ponds—farm ponds, detention ponds, or impoundments below 0.01 km2—serve important human needs throughout most large river basins. Yet the role of small ponds in regional nutrient and sediment budgets is essentially unknown, currently making it impossible to evaluate their management potential to achieve water quality objectives. Here we used new hydrography data sets and found that...
Authors
Noah Schmadel, Judson Harvey, Gregory E. Schwarz, Richard Alexander, Jesus D. Gomez-Velez, Durelle Scott, Scott W. Ator
Estimates of long-term mean daily streamflow and annual nutrient and suspended-sediment loads considered for use in regional SPARROW models of the Conterminous United States, 2012 base year Estimates of long-term mean daily streamflow and annual nutrient and suspended-sediment loads considered for use in regional SPARROW models of the Conterminous United States, 2012 base year
Streamflow, nutrient, and sediment concentration data needed to estimate long-term mean daily streamflow and annual constituent loads were compiled from Federal, State, Tribal, and regional agencies, universities, and nongovernmental organizations. The streamflow and loads are used to develop Spatially Referenced Regressions on Watershed Attributes (SPARROW) models. SPARROW models help...
Authors
David A. Saad, Gregory E. Schwarz, Denise M. Argue, David W. Anning, Scott A. Ator, Anne B. Hoos, Stephen D. Preston, Dale M. Robertson, Daniel Wise
Toward explaining nitrogen and phosphorus trends in Chesapeake Bay tributaries, 1992-2012 Toward explaining nitrogen and phosphorus trends in Chesapeake Bay tributaries, 1992-2012
Understanding trends in stream chemistry is critical to watershed management, and often complicated by multiple contaminant sources and landscape conditions changing over varying time scales. We adapted spatially-referenced regression (SPARROW) to infer causes of recent nutrient trends in Chesapeake Bay tributaries by relating observed fluxes during 1992, 2002, and 2012 to contemporary...
Authors
Scott Ator, Ana M. Garcia, Gregory E. Schwarz, Joel D. Blomquist, Andrew J. Sekellick
Adapting a regional water-quality model for local application: A case study for Tennessee, USA Adapting a regional water-quality model for local application: A case study for Tennessee, USA
We evaluated whether SPAtially Referenced Regression On Watershed attributes (SPARROW) models calibrated for two adjacent USA regions could be applied at the local scale to support management decisions for streams in Tennessee. Nutrient-source apportionment of load is important for this local-scale application and demands careful consideration of uncertainty in the calibrated...
Authors
Anne B. Hoos, Sherry H. Wang, Gregory E. Schwarz
Catchment-level estimates of nitrogen and phosphorus agricultural use from commercial fertilizer sales for the conterminous United States, 2012 Catchment-level estimates of nitrogen and phosphorus agricultural use from commercial fertilizer sales for the conterminous United States, 2012
Nutrient inputs from commercial agricultural fertilizer, particularly nitrogen and phosphorus, are important factors contributing to the degradation of surface-water quality and the alteration of aquatic ecosystems. Despite this importance, information about the application of fertilizer to agricultural land is not available in a consistent manner across the United States at a scale...
Authors
Jana S. Stewart, Gregory E. Schwarz, John W. Brakebill, Stephen D. Preston
The role of baseflow in dissolved solids delivery to streams in the Upper Colorado River Basin The role of baseflow in dissolved solids delivery to streams in the Upper Colorado River Basin
Salinity has a major effect on water users in the Colorado River Basin, estimated to cause almost $300 million per year in economic damages. The Colorado River Basin Salinity Control Program implements and manages projects to reduce salinity loads, investing millions of dollars per year in irrigation upgrades, canal projects, and other mitigation strategies. To inform and improve...
Authors
Christine Rumsey, Matthew P. Miller, Gregory E. Schwarz, Robert M. Hirsch, David D. Susong
Science and Products
Filter Total Items: 68
Small ponds in headwater catchments are a dominant influence on regional nutrient and sediment budgets Small ponds in headwater catchments are a dominant influence on regional nutrient and sediment budgets
Small ponds—farm ponds, detention ponds, or impoundments below 0.01 km2—serve important human needs throughout most large river basins. Yet the role of small ponds in regional nutrient and sediment budgets is essentially unknown, currently making it impossible to evaluate their management potential to achieve water quality objectives. Here we used new hydrography data sets and found that...
Authors
Noah Schmadel, Judson Harvey, Gregory E. Schwarz, Richard Alexander, Jesus D. Gomez-Velez, Durelle Scott, Scott W. Ator
Estimates of long-term mean daily streamflow and annual nutrient and suspended-sediment loads considered for use in regional SPARROW models of the Conterminous United States, 2012 base year Estimates of long-term mean daily streamflow and annual nutrient and suspended-sediment loads considered for use in regional SPARROW models of the Conterminous United States, 2012 base year
Streamflow, nutrient, and sediment concentration data needed to estimate long-term mean daily streamflow and annual constituent loads were compiled from Federal, State, Tribal, and regional agencies, universities, and nongovernmental organizations. The streamflow and loads are used to develop Spatially Referenced Regressions on Watershed Attributes (SPARROW) models. SPARROW models help...
Authors
David A. Saad, Gregory E. Schwarz, Denise M. Argue, David W. Anning, Scott A. Ator, Anne B. Hoos, Stephen D. Preston, Dale M. Robertson, Daniel Wise
Toward explaining nitrogen and phosphorus trends in Chesapeake Bay tributaries, 1992-2012 Toward explaining nitrogen and phosphorus trends in Chesapeake Bay tributaries, 1992-2012
Understanding trends in stream chemistry is critical to watershed management, and often complicated by multiple contaminant sources and landscape conditions changing over varying time scales. We adapted spatially-referenced regression (SPARROW) to infer causes of recent nutrient trends in Chesapeake Bay tributaries by relating observed fluxes during 1992, 2002, and 2012 to contemporary...
Authors
Scott Ator, Ana M. Garcia, Gregory E. Schwarz, Joel D. Blomquist, Andrew J. Sekellick
Adapting a regional water-quality model for local application: A case study for Tennessee, USA Adapting a regional water-quality model for local application: A case study for Tennessee, USA
We evaluated whether SPAtially Referenced Regression On Watershed attributes (SPARROW) models calibrated for two adjacent USA regions could be applied at the local scale to support management decisions for streams in Tennessee. Nutrient-source apportionment of load is important for this local-scale application and demands careful consideration of uncertainty in the calibrated...
Authors
Anne B. Hoos, Sherry H. Wang, Gregory E. Schwarz
Catchment-level estimates of nitrogen and phosphorus agricultural use from commercial fertilizer sales for the conterminous United States, 2012 Catchment-level estimates of nitrogen and phosphorus agricultural use from commercial fertilizer sales for the conterminous United States, 2012
Nutrient inputs from commercial agricultural fertilizer, particularly nitrogen and phosphorus, are important factors contributing to the degradation of surface-water quality and the alteration of aquatic ecosystems. Despite this importance, information about the application of fertilizer to agricultural land is not available in a consistent manner across the United States at a scale...
Authors
Jana S. Stewart, Gregory E. Schwarz, John W. Brakebill, Stephen D. Preston
The role of baseflow in dissolved solids delivery to streams in the Upper Colorado River Basin The role of baseflow in dissolved solids delivery to streams in the Upper Colorado River Basin
Salinity has a major effect on water users in the Colorado River Basin, estimated to cause almost $300 million per year in economic damages. The Colorado River Basin Salinity Control Program implements and manages projects to reduce salinity loads, investing millions of dollars per year in irrigation upgrades, canal projects, and other mitigation strategies. To inform and improve...
Authors
Christine Rumsey, Matthew P. Miller, Gregory E. Schwarz, Robert M. Hirsch, David D. Susong