David M Wolock, Ph.D.
David Wolock is a Supervisory Hydrologist with the USGS Water Resources Mission Area.
Science and Products
Filter Total Items: 13
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Nitrate Loads and Concentrations in Surface-Water Base Flow and Shallow Groundwater for Selected Basins in the United States, Water Years 1990-2006 Nitrate Loads and Concentrations in Surface-Water Base Flow and Shallow Groundwater for Selected Basins in the United States, Water Years 1990-2006
Hydrograph separation was used to determine the base-flow component of streamflow for 148 sites sampled as part of the National Water-Quality Assessment program. Sites in the Southwest and the Northwest tend to have base-flow index values greater than 0.5. Sites in the Midwest and the eastern portion of the Southern Plains generally have values less than 0.5. Base-flow index values for...
Authors
Norman Spahr, Neil Dubrovsky, JoAnn Gronberg, O. Franke, David Wolock
Development and Application of Regression Models for Estimating Nutrient Concentrations in Streams of the Conterminous United States, 1992-2001 Development and Application of Regression Models for Estimating Nutrient Concentrations in Streams of the Conterminous United States, 1992-2001
Data collected for the U.S. Geological Survey National Water-Quality Assessment program from 1992-2001 were used to investigate the relations between nutrient concentrations and nutrient sources, hydrology, and basin characteristics. Regression models were developed to estimate annual flow-weighted concentrations of total nitrogen and total phosphorus using explanatory variables derived...
Authors
Norman Spahr, David Mueller, David Wolock, Kerie Hitt, JoAnn Gronberg
Design of Cycle 3 of the National Water-Quality Assessment Program, 2013-2022: Part 1: Framework of Water-Quality Issues and Potential Approaches Design of Cycle 3 of the National Water-Quality Assessment Program, 2013-2022: Part 1: Framework of Water-Quality Issues and Potential Approaches
In 1991, the U.S. Congress established the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program to develop long-term, nationally consistent information on the quality of the Nation's streams and groundwater. Congress recognized the critical need for this information to support scientifically sound management, regulatory, and policy decisions concerning the...
Authors
Gary Rowe, Kenneth Belitz, Hedeff Essaid, Robert Gilliom, Pixie Hamilton, Anne Hoos, Dennis Lynch, Mark Munn, David Wolock
Streamflow of 2009--Water year summary Streamflow of 2009--Water year summary
The maps and graph in this summary describe streamflow conditions for water-year 2009 (October 1, 2008 to September 30, 2009) in the context of the 80-year period 1930-2009, unless otherwise noted. The illustrations are based on observed data from the U.S. Geological Survey's National Streamflow Information Program. The period 1930-2009 was used because prior to 1930, the number of...
Authors
Jian Xiaodong, David Wolock, Harry Lins, Steve Brady
Long-term variability in Northern Hemisphere snow cover and associations with warmer winters Long-term variability in Northern Hemisphere snow cover and associations with warmer winters
A monthly snow accumulation and melt model is used with gridded monthly temperature and precipitation data for the Northern Hemisphere to generate time series of March snow-covered area (SCA) for the period 1905 through 2002. The time series of estimated SCA for March is verified by comparison with previously published time series of SCA for the Northern Hemisphere. The time series of...
Authors
Gregory J. McCabe, David Wolock
Long-term variability in Northern Hemisphere snow cover and associations with warmer winters Long-term variability in Northern Hemisphere snow cover and associations with warmer winters
A monthly snow accumulation and melt model is used with gridded monthly temperature and precipitation data for the Northern Hemisphere to generate time series of March snow-covered area (SCA) for the period 1905 through 2002. The time series of estimated SCA for March is verified by comparison with previously published time series of SCA for the Northern Hemisphere. The time series of...
Authors
G.J. McCabe, D.M. Wolock
Identifying Hydrologic Processes in Agricultural Watersheds Using Precipitation-Runoff Models Identifying Hydrologic Processes in Agricultural Watersheds Using Precipitation-Runoff Models
Understanding the fate and transport of agricultural chemicals applied to agricultural fields will assist in designing the most effective strategies to prevent water-quality impairments. At a watershed scale, the processes controlling the fate and transport of agricultural chemicals are generally understood only conceptually. To examine the applicability of conceptual models to the...
Authors
Joshua Linard, David Wolock, Richard M. T. Webb, Michael Wieczorek
Regression models for explaining and predicting concentrations of organochlorine pesticides in fish from streams in the United States Regression models for explaining and predicting concentrations of organochlorine pesticides in fish from streams in the United States
Empirical regression models were developed for estimating concentrations of dieldrin, total chlordane, and total DDT in whole fish from U.S. streams. Models were based on pesticide concentrations measured in whole fish at 648 stream sites nationwide (1992-2001) as part of the U.S. Geological Survey's National Water Quality Assessment Program. Explanatory variables included fish lipid...
Authors
Lisa Nowell, Charles Crawford, Robert Gilliom, Naomi Nakagaki, Wesley Stone, Gail Thelin, David Wolock
Identifying pathways and processes affecting nitrate and orthophosphate inputs to streams in agricultural watersheds Identifying pathways and processes affecting nitrate and orthophosphate inputs to streams in agricultural watersheds
Understanding nutrient pathways to streams will improve nutrient management strategies and estimates of the time lag between when changes in land use practices occur and when water quality effects that result from these changes are observed. Nitrate and orthophosphate (OP) concentrations in several environmental compartments were examined in watersheds having a range of base flow index...
Authors
A. J. Tesoriero, J.H. Duff, D.M. Wolock, N.E. Spahr, J.E. Almendinger
Predicting the natural flow regime: Models for assessing hydrological alteration in streams Predicting the natural flow regime: Models for assessing hydrological alteration in streams
Understanding the extent to which natural streamflow characteristics have been altered is an important consideration for ecological assessments of streams. Assessing hydrologic condition requires that we quantify the attributes of the flow regime that would be expected in the absence of anthropogenic modifications. The objective of this study was to evaluate whether selected streamflow...
Authors
D.M. Carlisle, J. Falcone, D.M. Wolock, M. Meador, R.H. Norris
Streamflow of 2008--Water year summary Streamflow of 2008--Water year summary
The maps and graphs appearing in this summary describe streamflow conditions for water-year 2008 (October 1, 2007 to September 30, 2008) in the context of the 79-year period 1930-2008, unless otherwise noted. The illustrations are based on observed data from the U.S. Geological Survey's (USGS) National Streamflow Information Program. The period 1930-2008 was used because prior to 1930...
Authors
Jian Xiaodong, David Wolock, Harry Lins, Steve Brady
Recent declines in western U.S. snowpack in the context of twentieth-century climate variability Recent declines in western U.S. snowpack in the context of twentieth-century climate variability
A monthly snow accumulation and melt model was used with monthly Precipitation-elevation Regressions on Independent Slopes Model (PRISM) temperature and precipitation data to generate time series of 1 April snow water equivalent (SWE) for 1900 through 2008 in the western United States. Averaged across the western United States, SWE generally was higher than long-term (1900–2008) average...
Authors
Gregory J. McCabe, David Wolock
Science and Products
Filter Total Items: 13
No Result Found
Filter Total Items: 134
Nitrate Loads and Concentrations in Surface-Water Base Flow and Shallow Groundwater for Selected Basins in the United States, Water Years 1990-2006 Nitrate Loads and Concentrations in Surface-Water Base Flow and Shallow Groundwater for Selected Basins in the United States, Water Years 1990-2006
Hydrograph separation was used to determine the base-flow component of streamflow for 148 sites sampled as part of the National Water-Quality Assessment program. Sites in the Southwest and the Northwest tend to have base-flow index values greater than 0.5. Sites in the Midwest and the eastern portion of the Southern Plains generally have values less than 0.5. Base-flow index values for...
Authors
Norman Spahr, Neil Dubrovsky, JoAnn Gronberg, O. Franke, David Wolock
Development and Application of Regression Models for Estimating Nutrient Concentrations in Streams of the Conterminous United States, 1992-2001 Development and Application of Regression Models for Estimating Nutrient Concentrations in Streams of the Conterminous United States, 1992-2001
Data collected for the U.S. Geological Survey National Water-Quality Assessment program from 1992-2001 were used to investigate the relations between nutrient concentrations and nutrient sources, hydrology, and basin characteristics. Regression models were developed to estimate annual flow-weighted concentrations of total nitrogen and total phosphorus using explanatory variables derived...
Authors
Norman Spahr, David Mueller, David Wolock, Kerie Hitt, JoAnn Gronberg
Design of Cycle 3 of the National Water-Quality Assessment Program, 2013-2022: Part 1: Framework of Water-Quality Issues and Potential Approaches Design of Cycle 3 of the National Water-Quality Assessment Program, 2013-2022: Part 1: Framework of Water-Quality Issues and Potential Approaches
In 1991, the U.S. Congress established the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program to develop long-term, nationally consistent information on the quality of the Nation's streams and groundwater. Congress recognized the critical need for this information to support scientifically sound management, regulatory, and policy decisions concerning the...
Authors
Gary Rowe, Kenneth Belitz, Hedeff Essaid, Robert Gilliom, Pixie Hamilton, Anne Hoos, Dennis Lynch, Mark Munn, David Wolock
Streamflow of 2009--Water year summary Streamflow of 2009--Water year summary
The maps and graph in this summary describe streamflow conditions for water-year 2009 (October 1, 2008 to September 30, 2009) in the context of the 80-year period 1930-2009, unless otherwise noted. The illustrations are based on observed data from the U.S. Geological Survey's National Streamflow Information Program. The period 1930-2009 was used because prior to 1930, the number of...
Authors
Jian Xiaodong, David Wolock, Harry Lins, Steve Brady
Long-term variability in Northern Hemisphere snow cover and associations with warmer winters Long-term variability in Northern Hemisphere snow cover and associations with warmer winters
A monthly snow accumulation and melt model is used with gridded monthly temperature and precipitation data for the Northern Hemisphere to generate time series of March snow-covered area (SCA) for the period 1905 through 2002. The time series of estimated SCA for March is verified by comparison with previously published time series of SCA for the Northern Hemisphere. The time series of...
Authors
Gregory J. McCabe, David Wolock
Long-term variability in Northern Hemisphere snow cover and associations with warmer winters Long-term variability in Northern Hemisphere snow cover and associations with warmer winters
A monthly snow accumulation and melt model is used with gridded monthly temperature and precipitation data for the Northern Hemisphere to generate time series of March snow-covered area (SCA) for the period 1905 through 2002. The time series of estimated SCA for March is verified by comparison with previously published time series of SCA for the Northern Hemisphere. The time series of...
Authors
G.J. McCabe, D.M. Wolock
Identifying Hydrologic Processes in Agricultural Watersheds Using Precipitation-Runoff Models Identifying Hydrologic Processes in Agricultural Watersheds Using Precipitation-Runoff Models
Understanding the fate and transport of agricultural chemicals applied to agricultural fields will assist in designing the most effective strategies to prevent water-quality impairments. At a watershed scale, the processes controlling the fate and transport of agricultural chemicals are generally understood only conceptually. To examine the applicability of conceptual models to the...
Authors
Joshua Linard, David Wolock, Richard M. T. Webb, Michael Wieczorek
Regression models for explaining and predicting concentrations of organochlorine pesticides in fish from streams in the United States Regression models for explaining and predicting concentrations of organochlorine pesticides in fish from streams in the United States
Empirical regression models were developed for estimating concentrations of dieldrin, total chlordane, and total DDT in whole fish from U.S. streams. Models were based on pesticide concentrations measured in whole fish at 648 stream sites nationwide (1992-2001) as part of the U.S. Geological Survey's National Water Quality Assessment Program. Explanatory variables included fish lipid...
Authors
Lisa Nowell, Charles Crawford, Robert Gilliom, Naomi Nakagaki, Wesley Stone, Gail Thelin, David Wolock
Identifying pathways and processes affecting nitrate and orthophosphate inputs to streams in agricultural watersheds Identifying pathways and processes affecting nitrate and orthophosphate inputs to streams in agricultural watersheds
Understanding nutrient pathways to streams will improve nutrient management strategies and estimates of the time lag between when changes in land use practices occur and when water quality effects that result from these changes are observed. Nitrate and orthophosphate (OP) concentrations in several environmental compartments were examined in watersheds having a range of base flow index...
Authors
A. J. Tesoriero, J.H. Duff, D.M. Wolock, N.E. Spahr, J.E. Almendinger
Predicting the natural flow regime: Models for assessing hydrological alteration in streams Predicting the natural flow regime: Models for assessing hydrological alteration in streams
Understanding the extent to which natural streamflow characteristics have been altered is an important consideration for ecological assessments of streams. Assessing hydrologic condition requires that we quantify the attributes of the flow regime that would be expected in the absence of anthropogenic modifications. The objective of this study was to evaluate whether selected streamflow...
Authors
D.M. Carlisle, J. Falcone, D.M. Wolock, M. Meador, R.H. Norris
Streamflow of 2008--Water year summary Streamflow of 2008--Water year summary
The maps and graphs appearing in this summary describe streamflow conditions for water-year 2008 (October 1, 2007 to September 30, 2008) in the context of the 79-year period 1930-2008, unless otherwise noted. The illustrations are based on observed data from the U.S. Geological Survey's (USGS) National Streamflow Information Program. The period 1930-2008 was used because prior to 1930...
Authors
Jian Xiaodong, David Wolock, Harry Lins, Steve Brady
Recent declines in western U.S. snowpack in the context of twentieth-century climate variability Recent declines in western U.S. snowpack in the context of twentieth-century climate variability
A monthly snow accumulation and melt model was used with monthly Precipitation-elevation Regressions on Independent Slopes Model (PRISM) temperature and precipitation data to generate time series of 1 April snow water equivalent (SWE) for 1900 through 2008 in the western United States. Averaged across the western United States, SWE generally was higher than long-term (1900–2008) average...
Authors
Gregory J. McCabe, David Wolock