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
Dam impact/disturbance metrics for the conterminous United States, 1800 to 2018 Dam impact/disturbance metrics for the conterminous United States, 1800 to 2018
This metadata record describes two metrics that quantitatively measure the impact of reservoir storage on every flowline in the NHDPlus version 2 data suite (NHDPlusV2) for the conterminous United States. These metrics are computed for every 10 years from 1800 - 2015. The first metric (DamIndex_EROM.zip) estimates reservoir storage intensity in units of days based on reservoir storage in...
Trends in selected streamflow metrics at reference streamgages in the conterminous United States, 1980-2014 Trends in selected streamflow metrics at reference streamgages in the conterminous United States, 1980-2014
This dataset includes four tables related to annual trends in streamflow metrics at 599 reference streamgages in the conterminous United States for the period 1955-2014. Reference streamgages are defined here as gages with drainage basins that are minimally impacted by anthropogenic effects such as reservoirs or urbanization. The four tables are: 1) computed annual values for 16...
Natural Monthly Flow Estimates for the Conterminous United States, 1950-2015 Natural Monthly Flow Estimates for the Conterminous United States, 1950-2015
This metadata record describes monthly estimates of natural stream flows for greater than 2.5 million stream reaches, defined by the National Hydrography Dataset (NHD) Version 2.0, in the conterminous United States for the period 1950-2015. A statistical machine learning technique - random forest modeling - was applied to estimate natural flows using 200 potential predictor variables...
Monthly Streamflows, Drought Indices, and Supporting Statistics for USGS Gage Stations Used to Identify Variability of Hydrological Droughts in the Conterminous United States, 1951 through 2014 Monthly Streamflows, Drought Indices, and Supporting Statistics for USGS Gage Stations Used to Identify Variability of Hydrological Droughts in the Conterminous United States, 1951 through 2014
A table is presented listing: (1) monthly streamflows, (2) drought duration dates, (3) drought severity indices, (4) supporting statistics, and (5) identification tags, for analysis of hydrological droughts in the Conterminous United States (CONUS). Data were summarized from USGS streamflow daily values (DV), readily available from the U.S. Geological Survey National Water Information...
Water Balance Model Inputs and Outputs for the Conterminous United States, 1900-2015 Water Balance Model Inputs and Outputs for the Conterminous United States, 1900-2015
This metadata record describes monthly input and output data covering the period 1900-2015 for a water-balance model described in McCabe and Wolock (2011). The input datasets are precipitation (PPT) and air temperature (TAV) from the PRISM group at Oregon State University. The model outputs include estimated potential evapotranspiration (PET), actual evapotranspiration (AET), runoff (RUN...
Matched ecological assessment and stream gaging data for the CONUS Matched ecological assessment and stream gaging data for the CONUS
Ecological assessment data from the USGS National Water-Quality Assessment Program and the USEPA National River and Stream Assessment were reviewed and records were retained from sampling sites co-located with active USGS stream gages. A limited amount of ancillary data, including location, physical watershed features, and basic water chemistry data for each site were also retained.
Filter Total Items: 134
Evaluation of machine learning approaches for predicting streamflow metrics across the conterminous United States Evaluation of machine learning approaches for predicting streamflow metrics across the conterminous United States
Few regional or national scale studies have evaluated machine learning approaches for predicting streamflow metrics at ungaged locations. Most such studies are limited by the number of dimensions of the streamflow regime investigated. This study, in contrast, provides a comprehensive evaluation of the streamflow regime based on three widely available machine learning approaches (support...
Authors
Ken Eng, David M. Wolock
Going beyond low flows: Streamflow drought deficit and duration illuminate distinct spatiotemporal drought patterns and trends in the U.S. during the last century Going beyond low flows: Streamflow drought deficit and duration illuminate distinct spatiotemporal drought patterns and trends in the U.S. during the last century
Streamflow drought is a recurring challenge, and understanding spatiotemporal patterns of past droughts is needed to manage future water resources. We examined regional patterns in streamflow drought metrics and compared these metrics to low flow timing and magnitude using long-term daily records for 555 minimally disturbed watersheds. For each streamgage, we calculated streamflow...
Authors
John C. Hammond, Caelan E. Simeone, Jory Seth Hecht, Glenn A. Hodgkins, Melissa A. Lombard, Gregory J. McCabe, David M. Wolock, Michael Wieczorek, Carolyn G Olson, Todd Caldwell, Robert W. Dudley, Adam N. Price
Streamflow—Water year 2021 Streamflow—Water year 2021
The maps and graphs in this summary describe national streamflow conditions for water year 2021 (a water year is the period from October 1 to September 30 and is designated by the year in which it ends; for example, water year 2021 was from October 1, 2020, to September 30, 2021) in the context of streamflow ranks relative to the 92-year period of water years 1930–2021. Annual runoff in...
Authors
Xiaodong Jian, David M. Wolock, Harry F. Lins, Ronald J. Henderson, Steven J. Brady
Extensive droughts in the conterminous United States during multiple centuries Extensive droughts in the conterminous United States during multiple centuries
Extensive and severe droughts have substantial effects on water supplies, agriculture, and aquatic ecosystems. To better understand these droughts, we used tree-ring-based reconstructions of the Palmer drought severity index (PDSI) for the period 1475–2017 to examine droughts that covered at least 33% of the conterminous United States (CONUS). We identified 37 spatially extensive drought...
Authors
Gregory J. McCabe, David M. Wolock
Nitrogen in the Chesapeake Bay watershed—A century of change, 1950–2050 Nitrogen in the Chesapeake Bay watershed—A century of change, 1950–2050
Foreword Sustaining the quality of the Nation’s water resources and the health of our diverse ecosystems depends on the availability of sound water-resources data and information to develop effective, science-based policies. Effective management of water resources also brings more certainty and efficiency to important economic sectors. Taken together, these actions lead to immediate and...
Authors
John W. Clune, Paul D. Capel, Matthew P. Miller, Douglas A. Burns, Andrew J. Sekellick, Peter R. Claggett, Richard H. Coupe, Rosemary M. Fanelli, Ana Maria Garcia, Jeff P. Raffensperger, Silvia Terziotti, Gopal Bhatt, Joel D. Blomquist, Kristina G. Hopkins, Jennifer L. Keisman, Lewis C. Linker, Gary W. Shenk, Richard A. Smith, Alexander M. Soroka, James S. Webber, David M. Wolock, Qian Zhang
Streamflow—Water year 2020 Streamflow—Water year 2020
The maps and graphs in this summary describe national streamflow conditions for water year 2020 (October 1, 2019, to September 30, 2020) in the context of streamflow ranks relative to the 91-year period of water years 1930–2020. Annual runoff in the Nation’s rivers and streams during water year 2020 (11.10 inches) was higher than the long-term (1930–2020) mean annual runoff of 9.40...
Authors
Xiaodong Jian, David M. Wolock, Harry F. Lins, Ronald J. Henderson, Steven J. Brady
Science and Products
Filter Total Items: 13
Dam impact/disturbance metrics for the conterminous United States, 1800 to 2018 Dam impact/disturbance metrics for the conterminous United States, 1800 to 2018
This metadata record describes two metrics that quantitatively measure the impact of reservoir storage on every flowline in the NHDPlus version 2 data suite (NHDPlusV2) for the conterminous United States. These metrics are computed for every 10 years from 1800 - 2015. The first metric (DamIndex_EROM.zip) estimates reservoir storage intensity in units of days based on reservoir storage in...
Trends in selected streamflow metrics at reference streamgages in the conterminous United States, 1980-2014 Trends in selected streamflow metrics at reference streamgages in the conterminous United States, 1980-2014
This dataset includes four tables related to annual trends in streamflow metrics at 599 reference streamgages in the conterminous United States for the period 1955-2014. Reference streamgages are defined here as gages with drainage basins that are minimally impacted by anthropogenic effects such as reservoirs or urbanization. The four tables are: 1) computed annual values for 16...
Natural Monthly Flow Estimates for the Conterminous United States, 1950-2015 Natural Monthly Flow Estimates for the Conterminous United States, 1950-2015
This metadata record describes monthly estimates of natural stream flows for greater than 2.5 million stream reaches, defined by the National Hydrography Dataset (NHD) Version 2.0, in the conterminous United States for the period 1950-2015. A statistical machine learning technique - random forest modeling - was applied to estimate natural flows using 200 potential predictor variables...
Monthly Streamflows, Drought Indices, and Supporting Statistics for USGS Gage Stations Used to Identify Variability of Hydrological Droughts in the Conterminous United States, 1951 through 2014 Monthly Streamflows, Drought Indices, and Supporting Statistics for USGS Gage Stations Used to Identify Variability of Hydrological Droughts in the Conterminous United States, 1951 through 2014
A table is presented listing: (1) monthly streamflows, (2) drought duration dates, (3) drought severity indices, (4) supporting statistics, and (5) identification tags, for analysis of hydrological droughts in the Conterminous United States (CONUS). Data were summarized from USGS streamflow daily values (DV), readily available from the U.S. Geological Survey National Water Information...
Water Balance Model Inputs and Outputs for the Conterminous United States, 1900-2015 Water Balance Model Inputs and Outputs for the Conterminous United States, 1900-2015
This metadata record describes monthly input and output data covering the period 1900-2015 for a water-balance model described in McCabe and Wolock (2011). The input datasets are precipitation (PPT) and air temperature (TAV) from the PRISM group at Oregon State University. The model outputs include estimated potential evapotranspiration (PET), actual evapotranspiration (AET), runoff (RUN...
Matched ecological assessment and stream gaging data for the CONUS Matched ecological assessment and stream gaging data for the CONUS
Ecological assessment data from the USGS National Water-Quality Assessment Program and the USEPA National River and Stream Assessment were reviewed and records were retained from sampling sites co-located with active USGS stream gages. A limited amount of ancillary data, including location, physical watershed features, and basic water chemistry data for each site were also retained.
Filter Total Items: 134
Evaluation of machine learning approaches for predicting streamflow metrics across the conterminous United States Evaluation of machine learning approaches for predicting streamflow metrics across the conterminous United States
Few regional or national scale studies have evaluated machine learning approaches for predicting streamflow metrics at ungaged locations. Most such studies are limited by the number of dimensions of the streamflow regime investigated. This study, in contrast, provides a comprehensive evaluation of the streamflow regime based on three widely available machine learning approaches (support...
Authors
Ken Eng, David M. Wolock
Going beyond low flows: Streamflow drought deficit and duration illuminate distinct spatiotemporal drought patterns and trends in the U.S. during the last century Going beyond low flows: Streamflow drought deficit and duration illuminate distinct spatiotemporal drought patterns and trends in the U.S. during the last century
Streamflow drought is a recurring challenge, and understanding spatiotemporal patterns of past droughts is needed to manage future water resources. We examined regional patterns in streamflow drought metrics and compared these metrics to low flow timing and magnitude using long-term daily records for 555 minimally disturbed watersheds. For each streamgage, we calculated streamflow...
Authors
John C. Hammond, Caelan E. Simeone, Jory Seth Hecht, Glenn A. Hodgkins, Melissa A. Lombard, Gregory J. McCabe, David M. Wolock, Michael Wieczorek, Carolyn G Olson, Todd Caldwell, Robert W. Dudley, Adam N. Price
Streamflow—Water year 2021 Streamflow—Water year 2021
The maps and graphs in this summary describe national streamflow conditions for water year 2021 (a water year is the period from October 1 to September 30 and is designated by the year in which it ends; for example, water year 2021 was from October 1, 2020, to September 30, 2021) in the context of streamflow ranks relative to the 92-year period of water years 1930–2021. Annual runoff in...
Authors
Xiaodong Jian, David M. Wolock, Harry F. Lins, Ronald J. Henderson, Steven J. Brady
Extensive droughts in the conterminous United States during multiple centuries Extensive droughts in the conterminous United States during multiple centuries
Extensive and severe droughts have substantial effects on water supplies, agriculture, and aquatic ecosystems. To better understand these droughts, we used tree-ring-based reconstructions of the Palmer drought severity index (PDSI) for the period 1475–2017 to examine droughts that covered at least 33% of the conterminous United States (CONUS). We identified 37 spatially extensive drought...
Authors
Gregory J. McCabe, David M. Wolock
Nitrogen in the Chesapeake Bay watershed—A century of change, 1950–2050 Nitrogen in the Chesapeake Bay watershed—A century of change, 1950–2050
Foreword Sustaining the quality of the Nation’s water resources and the health of our diverse ecosystems depends on the availability of sound water-resources data and information to develop effective, science-based policies. Effective management of water resources also brings more certainty and efficiency to important economic sectors. Taken together, these actions lead to immediate and...
Authors
John W. Clune, Paul D. Capel, Matthew P. Miller, Douglas A. Burns, Andrew J. Sekellick, Peter R. Claggett, Richard H. Coupe, Rosemary M. Fanelli, Ana Maria Garcia, Jeff P. Raffensperger, Silvia Terziotti, Gopal Bhatt, Joel D. Blomquist, Kristina G. Hopkins, Jennifer L. Keisman, Lewis C. Linker, Gary W. Shenk, Richard A. Smith, Alexander M. Soroka, James S. Webber, David M. Wolock, Qian Zhang
Streamflow—Water year 2020 Streamflow—Water year 2020
The maps and graphs in this summary describe national streamflow conditions for water year 2020 (October 1, 2019, to September 30, 2020) in the context of streamflow ranks relative to the 91-year period of water years 1930–2020. Annual runoff in the Nation’s rivers and streams during water year 2020 (11.10 inches) was higher than the long-term (1930–2020) mean annual runoff of 9.40...
Authors
Xiaodong Jian, David M. Wolock, Harry F. Lins, Ronald J. Henderson, Steven J. Brady