Gregory E Schwarz (Former Employee)
Science and Products
Filter Total Items: 68
Estimation of nutrient sources and transport for New Zealand using the hybrid mechanistic-statistical model SPARROW Estimation of nutrient sources and transport for New Zealand using the hybrid mechanistic-statistical model SPARROW
The hybrid mechanistic-statistical catchment model SPARROW was applied to predict the mean annual load of nitrogen and phosphorus in streams throughout New Zealand (270,000 km2). The loads from land areas, point sources, and erosion are routed through the drainage network (576,300 reaches) with first-order stream decay and attenuation in lakes and reservoirs. Model parameters were...
Authors
A.H. Elliot, R. B. Alexander, G. E. Schwarz, Ude Shankar, J.P.S. Sukias, Graham B. McBride
Estimates of diffuse phosphorus sources in surface waters of the United States using a spatially referenced watershed model Estimates of diffuse phosphorus sources in surface waters of the United States using a spatially referenced watershed model
The statistical watershed model SPARROW (SPAtially Referenced Regression On Watershed attributes) was used to estimate the sources and transport of total phosphorus (TP) in surface waters of the United States. We calibrated the model using stream measurements of TP from 336 watersheds of mixed land use and spatial data on topography, soils, stream hydrography, and land use (agriculture...
Authors
R. B. Alexander, R. A. Smith, G. E. Schwarz
Recent progress in the development of a SPARROW model of sediment for the conterminous U.S. Recent progress in the development of a SPARROW model of sediment for the conterminous U.S.
Suspended sediment has long been recognized as an important contaminant affecting water resources. Besides its direct role in determining water clarity, bridge scour and reservoir storage, sediment serves as a vehicle for the transport of many binding contaminants, including nutrients, trace metals, semi- volatile organic compounds, and numerous pesticides (U.S. Environmental Protection...
Authors
Gregory Schwarz, Richard Smith, Richard Alexander, John Gray
Natural background concentrations of nutrients in streams and rivers of the conterminous United States Natural background concentrations of nutrients in streams and rivers of the conterminous United States
Determining natural background concentrations of nutrients in watersheds in the developed world has been hampered by a lack of pristine sampling sites covering a range of climatic conditions and basin sizes. Using data from 63 minimally impacted U.S. Geological Survey reference basins, we developed empirical models of the background yield of total nitrogen (TN) and total phosphorus (TP)...
Authors
R. A. Smith, R. B. Alexander, G. E. Schwarz
ERF1_2 -- Enhanced River Reach File 2.0 ERF1_2 -- Enhanced River Reach File 2.0
The digital segmented network based on watershed boundaries, ERF1_2, includes enhancements to the U.S. Environmental Protection Agency's River Reach File 1 (RF1) (USEPA, 1996; DeWald and others, 1985) to support national and regional-scale surface water-quality modeling. Alexander and others (1999) developed ERF1, which assessed the hydrologic integrity of the digital reach traces and...
Authors
Jacqueline V. Nolan, John W. Brakebill, Richard B. Alexander, Gregory E. Schwarz
Estimation of nitrogen yields and loads from basins draining to Long Island Sound, 1988–98 Estimation of nitrogen yields and loads from basins draining to Long Island Sound, 1988–98
Monitoring data on total nitrogen concentrations and streamflow were used to estimate annual nonpoint nitrogen loads for 1988?98 at 28 monitoring sites and 26 unmonitored basins that drain to Long Island Sound. The estimated total nitrogen yields at monitoring sites were used with basin characteristics and ancillary data to develop a multiple-linear regression equation to estimate...
Authors
John R. Mullaney, Gregory E. Schwarz, Elaine C. Todd Trench
Science and Products
Filter Total Items: 68
Estimation of nutrient sources and transport for New Zealand using the hybrid mechanistic-statistical model SPARROW Estimation of nutrient sources and transport for New Zealand using the hybrid mechanistic-statistical model SPARROW
The hybrid mechanistic-statistical catchment model SPARROW was applied to predict the mean annual load of nitrogen and phosphorus in streams throughout New Zealand (270,000 km2). The loads from land areas, point sources, and erosion are routed through the drainage network (576,300 reaches) with first-order stream decay and attenuation in lakes and reservoirs. Model parameters were...
Authors
A.H. Elliot, R. B. Alexander, G. E. Schwarz, Ude Shankar, J.P.S. Sukias, Graham B. McBride
Estimates of diffuse phosphorus sources in surface waters of the United States using a spatially referenced watershed model Estimates of diffuse phosphorus sources in surface waters of the United States using a spatially referenced watershed model
The statistical watershed model SPARROW (SPAtially Referenced Regression On Watershed attributes) was used to estimate the sources and transport of total phosphorus (TP) in surface waters of the United States. We calibrated the model using stream measurements of TP from 336 watersheds of mixed land use and spatial data on topography, soils, stream hydrography, and land use (agriculture...
Authors
R. B. Alexander, R. A. Smith, G. E. Schwarz
Recent progress in the development of a SPARROW model of sediment for the conterminous U.S. Recent progress in the development of a SPARROW model of sediment for the conterminous U.S.
Suspended sediment has long been recognized as an important contaminant affecting water resources. Besides its direct role in determining water clarity, bridge scour and reservoir storage, sediment serves as a vehicle for the transport of many binding contaminants, including nutrients, trace metals, semi- volatile organic compounds, and numerous pesticides (U.S. Environmental Protection...
Authors
Gregory Schwarz, Richard Smith, Richard Alexander, John Gray
Natural background concentrations of nutrients in streams and rivers of the conterminous United States Natural background concentrations of nutrients in streams and rivers of the conterminous United States
Determining natural background concentrations of nutrients in watersheds in the developed world has been hampered by a lack of pristine sampling sites covering a range of climatic conditions and basin sizes. Using data from 63 minimally impacted U.S. Geological Survey reference basins, we developed empirical models of the background yield of total nitrogen (TN) and total phosphorus (TP)...
Authors
R. A. Smith, R. B. Alexander, G. E. Schwarz
ERF1_2 -- Enhanced River Reach File 2.0 ERF1_2 -- Enhanced River Reach File 2.0
The digital segmented network based on watershed boundaries, ERF1_2, includes enhancements to the U.S. Environmental Protection Agency's River Reach File 1 (RF1) (USEPA, 1996; DeWald and others, 1985) to support national and regional-scale surface water-quality modeling. Alexander and others (1999) developed ERF1, which assessed the hydrologic integrity of the digital reach traces and...
Authors
Jacqueline V. Nolan, John W. Brakebill, Richard B. Alexander, Gregory E. Schwarz
Estimation of nitrogen yields and loads from basins draining to Long Island Sound, 1988–98 Estimation of nitrogen yields and loads from basins draining to Long Island Sound, 1988–98
Monitoring data on total nitrogen concentrations and streamflow were used to estimate annual nonpoint nitrogen loads for 1988?98 at 28 monitoring sites and 26 unmonitored basins that drain to Long Island Sound. The estimated total nitrogen yields at monitoring sites were used with basin characteristics and ancillary data to develop a multiple-linear regression equation to estimate...
Authors
John R. Mullaney, Gregory E. Schwarz, Elaine C. Todd Trench