Glenn Hodgkins is a Research Hydrologist with the New England Water Science Center.
Glenn's work in recent years has focused on statistical hydrology at the regional, national, and international scale, primarily on the analysis of change and variability of historical streamflow and groundwater, and also on probabilistic forecasting and model evaluation. Glenn is the lead author or co-author on 25 peer-reviewed articles in hydrology and climate journals since 2002.
Science and Products
Long-Term Data Collection Provides Insight to Changes in Water Resources in New England
Primarily through the efforts of Glenn Hodgkins and Robert Dudley, the New England Water Science Center has been studying historical changes in streamflows, groundwater levels, and lake ice in New England and across the country for 20 years. Glenn and Rob have analyzed a wealth of historical data, including 100+ years of streamflow data and 150+ years of lake-ice data at some locations...
The Influence of Climatic, Watershed, and Water-use Changes on Extreme Low Streamflows in the United States
Extreme low streamflows impact water availability for human systems and ecosystems. Numerous researchers have analyzed trends in low streamflows in the U.S. There is no known published work, however, on historical trends over time in the most extreme low streamflows—the flows with the largest impacts on human systems and ecosystems. The current study attempts to fill this gap. The wealth of...
The Influence of Climatic changes on Extreme Streamflows in the United States
Hydrologic droughts and floods can have severe impacts on river infrastructure, water supply, and ecosystem functioning.
Trend Reproduction
As part of the National Water Budget Project, our objective is to quantify how well observed trends are simulated.
Hydrologic Climate Change Indicators
Background Streams and rivers are an important environmental resource and provide water for many human needs. Streamflow is a measure of the volume of water carried by rivers and streams. Changes in streamflow can directly influence the supply of water available for human consumption, irrigation, generating electricity, and other needs. In addition, many plants and animals depend on streamflow
Webinar: Historical Trends in Summer Precipitation, Baseflows, and Stormflows in New England and Projections of Seasonal Streamflows for Coastal Streams in Maine
Check out this webinar for more information on influencing water flow in Maine rivers and streams.
Impact of Changes in Streamflow and Temperature on Endangered Atlantic Salmon
Coastal rivers draining into the Gulf of Maine are home to the endangered Gulf of Maine Distinct Population Segment of Atlantic salmon. The Gulf of Maine population began to decline significantly by the late 19th century, leading to the closure of the commercial Atlantic salmon fishery in 1948. In recent years, populations have again begun to decrease again. State and federal fisheries biologists
U.S. Streamflow Drought During the Last Century: annual drought and low flow metrics, annual climate, and trends for the periods 1921-2020, 1951-2020 and 1981-2020
This dataset contains annual flow metrics quantifying drought and low streamflows for USGS GAGES-2 gages in the contiguous U.S. satisfying data completeness checks for the periods 1921-2020, 1951-2020, and 1981-2020. The dataset also contains annual climate variables from the USGS Monthly Water Balance Model (MWBM). The dataset provides trend analysis outputs for annual drought and low flow metric
Modeled and observed trends in streamflows at managed basins in the conterminous U.S. from October 1, 1983 through September 30, 2016
This data release contains trend results computed on the basis of modeled and observed daily streamflows at 1,257 gages across the conterminous U.S. from October 1, 1983 through September 30, 2016. Study gages were selected from the GAGES-II dataset of gages classified as non-reference which means streamflows may be affected by human influence. Modeled daily streamflows were computed using the det
Attributions for nonstationary peak streamflow records across the conterminous United States, 1941-2015 and 1966-2015
The U.S. Geological Survey Dakota Water Science Center, in cooperation with the Federal Highway Administration, analyzed annual peak-flow data to determine if trends are present and provide attribution of trends where possible. Work for the national trend attributions for nonstationary annual peak-flow records was broken into seven regions that are loosely based off of two-digit hydrologic unit wa
Modeled and observed trends at reference basins in the conterminous U.S. from October 1, 1983 through September 30, 2016
This data release contains trend results computed on the basis of modeled and observed daily streamflows at 502 reference gages across the conterminous U.S. from October 1, 1983 through September 30, 2016. Modeled daily streamflows were computed using the deterministic Precipitation Runoff Modeling System (PRMS), and five statistical techniques: Nearest-Neighbor Drainage Area Ratio (NNDAR), Map-Co
Peak-streamflow trends and change-points and basin characteristics for 2,683 U.S. Geological Survey streamgages in the conterminous U.S.
This data release contains drainage basin characteristics and peak-streamflow trend and change-point results for 2,683 U.S. Geological Survey (USGS) streamgages in the conterminous U.S. Data include streamgage identification number, name, drainage area, latitude, longitude, percent urban land use, dam storage, streamgage classification, record completeness status, lag-1 autocorrelation, trend slop
Data related to the degree of potential human influence near 2228 groundwater wells in the U.S. glacial aquifer system
This dataset contains information on the degree of potential human influence near 2228 groundwater wells in the U.S. glacial aquifer system. Data include well identification, name, latitude, longitude, potential-human-influence category, percent urban and crop land use in a 500 meter radius around each well, and measures of county-based groundwater use and irrigation.
Generalized linear models and input data for forecasting the probability of groundwater levels declining below specified low thresholds for the conterminous U.S.
This dataset contains model parameters and input data (.rdata files) for 258 models derived for wells in the conterminous United States. The models are generalized linear models with a binomial response variable (logistic regression) for forecasting the probability of groundwater levels declining or maintaining below specified low thresholds for any time of the year for forecast time horizons from
Filter Total Items: 60
A hydrologic perspective of major U.S. droughts
Drought is a recurring natural hazard that has substantial human and environmental impacts. Given continued global warming and associated climate change, there is concern that droughts could become more severe and longer lasting. To better monitor and understand drought development and persistence, it is helpful to understand the development and climatic drivers of past droughts. In this study we
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 drought duration
The occurrence of large floods in the United States in the modern hydroclimate regime: Seasonality, trends, and large-scale climate associations
Many studies investigate river floods by analyzing annual maximum series that record the largest flow of each year, including many within-bank events inconsequential for human communities. Fewer focus on larger floods, especially at the continental scale. Using 473 streamgages across the conterminous United States with near-natural flow from 1966 to 2015, we characterized the seasonality, occurren
Estimating flood magnitude and frequency on gaged and ungaged streams in Maine
Accurate estimates of flood frequency and magnitude on rivers and streams in Maine are a key component of effective flood risk management, flood mitigation, and flood recovery programs for the State. Flood-frequency estimates are published here for 148 streamgages in and adjacent to Maine. Equations are provided for users to compute flood-frequency estimates at any location on a stream that does n
Estimating flood magnitude and frequency on streams and rivers in Connecticut, based on data through water year 2015
The U.S. Geological Survey, in cooperation with the Connecticut Department of Transportation, updated flood-frequency estimates with 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities (2-, 5-, 10-, 25-, 50-, 100-, 200-, and 500-year recurrence intervals, respectively) for 141 streamgages in Connecticut and 11 streamgages in adjacent States using annual peak-flow data
Comparing trends in modeled and observed streamflows at minimally altered basins in the United States
We compared modeled and observed streamflow trends from 1984–2016 using five statistical transfer models and one deterministic, distributed-parameter, process-based model, for 26 flow metrics at 502 basins in the United States that are minimally influenced by development. We also looked at a measure of overall model fit and average bias. A higher percentage of basins, for all models, had relativel
Change points in annual peak streamflows: Method comparisons and historical change points in the United States
Change-point, or step-trend, detection is an active area of research in statistics and an area of great interest in hydrology because change points may be evidence of natural or anthropogenic changes in climatic, hydrologic, or landscape processes. A common change-point technique is the Pettitt test; however, many change-point methods are now available and testing of methods has been limited. This
Historical trend in the ratio of solid to total precipitation
No abstract available
Methods for estimating regional coefficient of skewness for unregulated streams in New England, based on data through water year 2011
The magnitude of annual exceedance probability floods is greatly affected by the coefficient of skewness (skew) of the annual peak flows at a streamgage. Standard flood frequency methods recommend weighting the station skew with a regional skew to better represent regional and stable conditions. This study presents an updated analysis of a regional skew for New England developed using a robust Bay
Northeast
The distinct seasonality of the Northeast’s climate supports a diverse natural landscape adapted to the extremes of cold, snowy winters and warm to hot, humid summers. This natural landscape provides the economic and cultural foundation for many rural communities, which are largely supported by a diverse range of agricultural, tourism, and natural resource-dependent industries (see Ch. 10: Ag & Ru
Generalized hydrogeologic framework and groundwater budget for a groundwater availability study for the glacial aquifer system of the United States
The glacial aquifer system groundwater availability study seeks to quantify (1) the status of groundwater resources in the glacial aquifer system, (2) how these resources have changed over time, and (3) likely system response to future changes in anthropogenic and environmental conditions. The glacial aquifer system extends from Maine to Alaska, although the focus of this report is the part of the
Science and Products
- Science
Long-Term Data Collection Provides Insight to Changes in Water Resources in New England
Primarily through the efforts of Glenn Hodgkins and Robert Dudley, the New England Water Science Center has been studying historical changes in streamflows, groundwater levels, and lake ice in New England and across the country for 20 years. Glenn and Rob have analyzed a wealth of historical data, including 100+ years of streamflow data and 150+ years of lake-ice data at some locations...The Influence of Climatic, Watershed, and Water-use Changes on Extreme Low Streamflows in the United States
Extreme low streamflows impact water availability for human systems and ecosystems. Numerous researchers have analyzed trends in low streamflows in the U.S. There is no known published work, however, on historical trends over time in the most extreme low streamflows—the flows with the largest impacts on human systems and ecosystems. The current study attempts to fill this gap. The wealth of...The Influence of Climatic changes on Extreme Streamflows in the United States
Hydrologic droughts and floods can have severe impacts on river infrastructure, water supply, and ecosystem functioning.Trend Reproduction
As part of the National Water Budget Project, our objective is to quantify how well observed trends are simulated.Hydrologic Climate Change Indicators
Background Streams and rivers are an important environmental resource and provide water for many human needs. Streamflow is a measure of the volume of water carried by rivers and streams. Changes in streamflow can directly influence the supply of water available for human consumption, irrigation, generating electricity, and other needs. In addition, many plants and animals depend on streamflowWebinar: Historical Trends in Summer Precipitation, Baseflows, and Stormflows in New England and Projections of Seasonal Streamflows for Coastal Streams in Maine
Check out this webinar for more information on influencing water flow in Maine rivers and streams.Impact of Changes in Streamflow and Temperature on Endangered Atlantic Salmon
Coastal rivers draining into the Gulf of Maine are home to the endangered Gulf of Maine Distinct Population Segment of Atlantic salmon. The Gulf of Maine population began to decline significantly by the late 19th century, leading to the closure of the commercial Atlantic salmon fishery in 1948. In recent years, populations have again begun to decrease again. State and federal fisheries biologists - Data
U.S. Streamflow Drought During the Last Century: annual drought and low flow metrics, annual climate, and trends for the periods 1921-2020, 1951-2020 and 1981-2020
This dataset contains annual flow metrics quantifying drought and low streamflows for USGS GAGES-2 gages in the contiguous U.S. satisfying data completeness checks for the periods 1921-2020, 1951-2020, and 1981-2020. The dataset also contains annual climate variables from the USGS Monthly Water Balance Model (MWBM). The dataset provides trend analysis outputs for annual drought and low flow metricModeled and observed trends in streamflows at managed basins in the conterminous U.S. from October 1, 1983 through September 30, 2016
This data release contains trend results computed on the basis of modeled and observed daily streamflows at 1,257 gages across the conterminous U.S. from October 1, 1983 through September 30, 2016. Study gages were selected from the GAGES-II dataset of gages classified as non-reference which means streamflows may be affected by human influence. Modeled daily streamflows were computed using the detAttributions for nonstationary peak streamflow records across the conterminous United States, 1941-2015 and 1966-2015
The U.S. Geological Survey Dakota Water Science Center, in cooperation with the Federal Highway Administration, analyzed annual peak-flow data to determine if trends are present and provide attribution of trends where possible. Work for the national trend attributions for nonstationary annual peak-flow records was broken into seven regions that are loosely based off of two-digit hydrologic unit waModeled and observed trends at reference basins in the conterminous U.S. from October 1, 1983 through September 30, 2016
This data release contains trend results computed on the basis of modeled and observed daily streamflows at 502 reference gages across the conterminous U.S. from October 1, 1983 through September 30, 2016. Modeled daily streamflows were computed using the deterministic Precipitation Runoff Modeling System (PRMS), and five statistical techniques: Nearest-Neighbor Drainage Area Ratio (NNDAR), Map-CoPeak-streamflow trends and change-points and basin characteristics for 2,683 U.S. Geological Survey streamgages in the conterminous U.S.
This data release contains drainage basin characteristics and peak-streamflow trend and change-point results for 2,683 U.S. Geological Survey (USGS) streamgages in the conterminous U.S. Data include streamgage identification number, name, drainage area, latitude, longitude, percent urban land use, dam storage, streamgage classification, record completeness status, lag-1 autocorrelation, trend slopData related to the degree of potential human influence near 2228 groundwater wells in the U.S. glacial aquifer system
This dataset contains information on the degree of potential human influence near 2228 groundwater wells in the U.S. glacial aquifer system. Data include well identification, name, latitude, longitude, potential-human-influence category, percent urban and crop land use in a 500 meter radius around each well, and measures of county-based groundwater use and irrigation.Generalized linear models and input data for forecasting the probability of groundwater levels declining below specified low thresholds for the conterminous U.S.
This dataset contains model parameters and input data (.rdata files) for 258 models derived for wells in the conterminous United States. The models are generalized linear models with a binomial response variable (logistic regression) for forecasting the probability of groundwater levels declining or maintaining below specified low thresholds for any time of the year for forecast time horizons from - Multimedia
- Publications
Filter Total Items: 60
A hydrologic perspective of major U.S. droughts
Drought is a recurring natural hazard that has substantial human and environmental impacts. Given continued global warming and associated climate change, there is concern that droughts could become more severe and longer lasting. To better monitor and understand drought development and persistence, it is helpful to understand the development and climatic drivers of past droughts. In this study weGoing 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 drought durationThe occurrence of large floods in the United States in the modern hydroclimate regime: Seasonality, trends, and large-scale climate associations
Many studies investigate river floods by analyzing annual maximum series that record the largest flow of each year, including many within-bank events inconsequential for human communities. Fewer focus on larger floods, especially at the continental scale. Using 473 streamgages across the conterminous United States with near-natural flow from 1966 to 2015, we characterized the seasonality, occurrenEstimating flood magnitude and frequency on gaged and ungaged streams in Maine
Accurate estimates of flood frequency and magnitude on rivers and streams in Maine are a key component of effective flood risk management, flood mitigation, and flood recovery programs for the State. Flood-frequency estimates are published here for 148 streamgages in and adjacent to Maine. Equations are provided for users to compute flood-frequency estimates at any location on a stream that does nEstimating flood magnitude and frequency on streams and rivers in Connecticut, based on data through water year 2015
The U.S. Geological Survey, in cooperation with the Connecticut Department of Transportation, updated flood-frequency estimates with 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities (2-, 5-, 10-, 25-, 50-, 100-, 200-, and 500-year recurrence intervals, respectively) for 141 streamgages in Connecticut and 11 streamgages in adjacent States using annual peak-flow dataComparing trends in modeled and observed streamflows at minimally altered basins in the United States
We compared modeled and observed streamflow trends from 1984–2016 using five statistical transfer models and one deterministic, distributed-parameter, process-based model, for 26 flow metrics at 502 basins in the United States that are minimally influenced by development. We also looked at a measure of overall model fit and average bias. A higher percentage of basins, for all models, had relativelChange points in annual peak streamflows: Method comparisons and historical change points in the United States
Change-point, or step-trend, detection is an active area of research in statistics and an area of great interest in hydrology because change points may be evidence of natural or anthropogenic changes in climatic, hydrologic, or landscape processes. A common change-point technique is the Pettitt test; however, many change-point methods are now available and testing of methods has been limited. ThisHistorical trend in the ratio of solid to total precipitation
No abstract availableMethods for estimating regional coefficient of skewness for unregulated streams in New England, based on data through water year 2011
The magnitude of annual exceedance probability floods is greatly affected by the coefficient of skewness (skew) of the annual peak flows at a streamgage. Standard flood frequency methods recommend weighting the station skew with a regional skew to better represent regional and stable conditions. This study presents an updated analysis of a regional skew for New England developed using a robust BayNortheast
The distinct seasonality of the Northeast’s climate supports a diverse natural landscape adapted to the extremes of cold, snowy winters and warm to hot, humid summers. This natural landscape provides the economic and cultural foundation for many rural communities, which are largely supported by a diverse range of agricultural, tourism, and natural resource-dependent industries (see Ch. 10: Ag & RuGeneralized hydrogeologic framework and groundwater budget for a groundwater availability study for the glacial aquifer system of the United States
The glacial aquifer system groundwater availability study seeks to quantify (1) the status of groundwater resources in the glacial aquifer system, (2) how these resources have changed over time, and (3) likely system response to future changes in anthropogenic and environmental conditions. The glacial aquifer system extends from Maine to Alaska, although the focus of this report is the part of the - News