Robert M Hirsch is a Research Hydrologist Emeritus for the USGS Water Resources Mission Area.
EGRET Software
Exploration and Graphics for RivEr Trends (EGRET) is an R package for evaluating long-term changes in river conditions (water quality and discharge). The EGRET user guide provides guidance on installation and use of the software, documentation of the analysis methods used, as well as information about the kinds of questions and approaches that the software can facilitate.
Statistical Methods in Water Resources
An applied statistics textbook for hydrology, environmental science, environmental engineering, geology, or biology that addresses distinctive features of environmental data. The text utilizes R, a programming language and open-source software environment, for all exercises and most graphics, and the R code used to generate figures and examples is provided for download.
My main interest is improving the analysis of hydrologic data, with a focus on the topic of trends in streamflow and trends in surface water quality. My research on this has resulted in the development of the EGRET software (Exploration and Graphics for RivEr Trends) written in R and available freely online.
The focus of my research is the description and understanding of long-term variability and change in surface-water quality and streamflow. I develop and apply new statistical tools to help characterize these changes to gain the best possible understanding of the nature of the change and its implications from a policy perspective (related to water quality improvement, flood hazard mitigation, water supply planning). This work has resulted in the development of the statistical method Weighted Regressions on Time, Discharge, and Season (WRTDS), which I have applied to the study of water quality trends in a variety of watersheds including Chesapeake Bay, the Mississippi River, Lake Erie, and Lake Champlain. This technique is a central feature of the EGRET R package. That package is designed to be a “toolbox” for analysis of daily streamflow data and surface water quality data.
My other major recent contribution is the publication of "Statistical Methods in Water Resources" the 2020 edition published as USGS Techniques and Methods (tm4A3). In addition to the pdf and the printed book, the text has on-line resources which include all of the data sets used as examples in the book, all of the R code used in the analysis of those data, and all of the R code used to produce the graphics in the book.
I hold a B.A. in Geology from Earlham College, an M.S. in Geology from the University of Washington, and a Ph.D. in Geography and Environmental Engineering at the Johns Hopkins University. I began my USGS career in 1976 and conducted research on water supply, water quality, pollutant transport, and flood frequency analysis. In 1993-1994 I was Acting Director of the USGS, and from 1994-2008 I was the Chief Hydrologist of the USGS. In 2008 I returned to research and since that time I have focused efforts on describing long-term changes in streamflow and water quality. I retired from the USGS in 2018 but continue to collaborate with colleagues inside and outside the USGS. I am a member of the Water Science and Technology Board of the NASEM and have served on four expert committees of that Board.
Science and Products
Evaluating chloride trends due to road-salt use and its impacts on water quality and aquatic organisms
Transport of dissolved organic matter by river networks from mountains to the sea: a re-examination of the role of flow across temporal and spatial scales
Flux of Nitrogen, Phosphorous, and Suspended Sediment from the Susquehanna River Basin to the Chesapeake Bay During Tropical Storm Lee, September 2011, as in Indicator of the Effects of Reservoir Sedimentation on Water Quality
Low-streamflow and precipitation trends for 183 U.S. Geological Survey streamgages in the Chesapeake Bay Watershed
Trends in 7-day-low streamflows at 174 USGS streamflow gages in the Chesapeake Bay watershed, Mid-Atlantic U.S.
Low-streamflow trends and basin characteristics for 2,482 U.S. Geological Survey streamgages in the conterminous U.S.
Water-quality trends and trend component estimates for the Nation's rivers and streams using Weighted Regressions on Time, Discharge, and Season (WRTDS) models and generalized flow normalization, 1972-2012
Growth of coal mining operations in the Elk River Valley (Canada) linked to increasing solute transport of Se, NO3-, and SO42- into the transboundary Koocanusa Reservoir (USA-Canada)
The occurrence of large floods in the United States in the modern hydroclimate regime: Seasonality, trends, and large-scale climate associations
Substantial declines in salinity observed across the Upper Colorado River Basin during the 20th century, 1929 to 2019
Statistical methods in water resources
Spatial and temporal patterns of low streamflow and precipitation changes in the Chesapeake Bay Watershed
Low streamflow trends at human-impacted and reference basins in the United States
River water-quality concentration and flux estimation can be improved by accounting for serial correlation through an autoregressive model
Accurate quantification of riverine water‐quality concentration and flux is challenging because monitoring programs typically collect concentration data at lower frequencies than discharge data. Statistical methods are often used to estimate concentration and flux on days without observations. One recently developed approach is the Weighted Regressions on Time, Discharge, and Season (WRTDS), which
An evaluation of methods for computing annual water-quality loads
Updating estimates of low-streamflow statistics to account for possible trends
Phosphorus and the Chesapeake Bay: Lingering issues and emerging concerns for agriculture
Tracking changes in nutrient delivery to western Lake Erie: Approaches to compensate for variability and trends in streamflow
The role of baseflow in dissolved solids delivery to streams in the Upper Colorado River Basin
EGRET
dataRetrieval
Science and Products
- Science
Evaluating chloride trends due to road-salt use and its impacts on water quality and aquatic organisms
Chloride, a key component of road salt, is soluble, highly mobile in water, and, at high concentrations, can be toxic to aquatic vegetation and wildlife. USGS scientists have been analyzing temporal, seasonal, and environmental trends in chloride concentrations across the U.S. to determine the effects that road salt may be having on water quality and aquatic organisms.Transport of dissolved organic matter by river networks from mountains to the sea: a re-examination of the role of flow across temporal and spatial scales
The transport of dissolved organic matter (DOM) by rivers is an important component of the global carbon cycle, affects ecosystems and water quality, and reflects biogeochemical and hydrological processes in watersheds. Understanding the fundamental relationships between discharge and DOM concentration and composition reveals important information about watershed flow paths, soil flushing, connectFlux of Nitrogen, Phosphorous, and Suspended Sediment from the Susquehanna River Basin to the Chesapeake Bay During Tropical Storm Lee, September 2011, as in Indicator of the Effects of Reservoir Sedimentation on Water Quality
Concentrations of nitrogen, phosphorus, and suspended sediment are measured at the U.S. Geological Survey streamgage at Conowingo Dam at the downstream end of the Susquehanna River Basin in Maryland, where the river flows into the Chesapeake Bay. During the period September 7–15, 2011, in the aftermath of Tropical Storm Lee, concentrations of these three constituents were among the highest ever... - Data
Low-streamflow and precipitation trends for 183 U.S. Geological Survey streamgages in the Chesapeake Bay Watershed
This data release contains low-streamflow trend results from 183 U.S. Geological Survey (USGS) streamgages and precipitation trend results from gaged watersheds within the Chesapeake Bay Watershed. Data include streamgage identification number, trend slopes and significance for several low-streamflow and precipitation metrics.Trends in 7-day-low streamflows at 174 USGS streamflow gages in the Chesapeake Bay watershed, Mid-Atlantic U.S.
This data set contains U.S. Geological Survey (USGS) streamgage identification numbers, begin and end years of the periods of streamflow record tested, Sen slope trends in the annual minimum 7-day streamflow for the period of record tested, the p-values (significance) of the trends, and the trend Sen slopes standardized by the standard deviations of the residual errors defined as the difference beLow-streamflow trends and basin characteristics for 2,482 U.S. Geological Survey streamgages in the conterminous U.S.
This data release contains drainage basin characteristics and low-streamflow trend results for 2,482 U.S. Geological Survey (USGS) streamgages in the conterminous U.S. Data include streamgage identification number, name, drainage area, latitude, longitude, percent developed land use, percent crop land use, dam storage, streamgage classification, record completeness status, and trend slopes and sigWater-quality trends and trend component estimates for the Nation's rivers and streams using Weighted Regressions on Time, Discharge, and Season (WRTDS) models and generalized flow normalization, 1972-2012
Nonstationary streamflow due to environmental and human-induced causes can affect water quality over time, yet these effects are poorly accounted for in water-quality trend models. This data release provides instream water-quality trends and estimates of two components of change, for sites across the Nation previously presented in Oelsner et al. (2017). We used previously calibrated Weighted Regre - Publications
Filter Total Items: 67
Growth of coal mining operations in the Elk River Valley (Canada) linked to increasing solute transport of Se, NO3-, and SO42- into the transboundary Koocanusa Reservoir (USA-Canada)
Koocanusa Reservoir (KOC) is a waterbody that spans the United States (U.S.) and Canadian border. Increasing concentrations of total selenium (Se), nitrate + nitrite (NO3–, nitrite is insignificant or not present), and sulfate (SO42–) in KOC and downstream in the Kootenai River (Kootenay River in Canada) are tied to expanding coal mining operations in the Elk River Watershed, Canada. Using a paireAuthorsMeryl Biesiot Storb, Ashley Morgan Bussell, Sara L. Caldwell Eldridge, Robert M. Hirsch, Travis S. SchmidtThe 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, occurrenAuthorsMathias Collins, Glenn A. Hodgkins, Stacey A. Archfield, Robert M. HirschSubstantial declines in salinity observed across the Upper Colorado River Basin during the 20th century, 1929 to 2019
Salinity in the Colorado River Basin causes an estimated $300 to $400 million per year in economic damages in the U.S. To inform and improve salinity‐control efforts, this study quantifies long‐term trends in salinity (dissolved solids) across the Upper Colorado River Basin (UCRB), including time periods prior to the construction of large dams and preceding the implementation of salinity‐control pAuthorsChristine Rumsey, Olivia L. Miller, Robert Hirsch, Thomas M. Marston, David SusongStatistical methods in water resources
This text began as a collection of class notes for a course on applied statistical methods for hydrologists taught at the U.S. Geological Survey (USGS) National Training Center. Course material was formalized and organized into a textbook, first published in 1992 by Elsevier as part of their Studies in Environmental Science series. In 2002, the work was made available online as a USGS report.The tAuthorsDennis R. Helsel, Robert M. Hirsch, Karen R. Ryberg, Stacey A. Archfield, Edward J. GilroySpatial and temporal patterns of low streamflow and precipitation changes in the Chesapeake Bay Watershed
Spatial and temporal patterns in low streamflows were investigated for 183 streamgages located in the Chesapeake Bay Watershed for the period 1939–2013. Metrics that represent different aspects of the frequency and magnitude of low streamflows were examined for trends: (1) the annual time series of seven‐day average minimum streamflow, (2) the scaled average deficit at or below the 2% mean daily sAuthorsBrandon J. Fleming, Stacey A. Archfield, Robert M. Hirsch, Julie E. Kiang, David M. WolockLow streamflow trends at human-impacted and reference basins in the United States
We present a continent-scale exploration of trends in annual 7-day low streamflows at 2482 U.S. Geological Survey streamgages across the conterminous United States over the past 100, 75, and 50 years (1916–2015, 1941–2015 and 1966–2015). We used basin characteristics to identify subsets of study basins representative of reference basins with streamflow relatively free from human effects (n = 259),AuthorsRobert W. Dudley, Robert M. Hirsch, Stacey A. Archfield, Annalise G. Blum, Benjamin RenardRiver water-quality concentration and flux estimation can be improved by accounting for serial correlation through an autoregressive model
Accurate quantification of riverine water‐quality concentration and flux is challenging because monitoring programs typically collect concentration data at lower frequencies than discharge data. Statistical methods are often used to estimate concentration and flux on days without observations. One recently developed approach is the Weighted Regressions on Time, Discharge, and Season (WRTDS), which
AuthorsQian Zhang, Robert M. HirschAn evaluation of methods for computing annual water-quality loads
The U.S. Geological Survey publishes information on the mass, or load, of water-quality constituents transported through rivers and streams sampled as part of the operation of the National Water Quality Network (NWQN). This study evaluates methods for computing annual water-quality loads, specifically with respect to procedures currently (2019) used at sites in the NWQN. Near-daily datasets of chlAuthorsCasey J. Lee, Robert M. Hirsch, Charles G. CrawfordUpdating estimates of low-streamflow statistics to account for possible trends
Accurate estimators of streamflow statistics are critical to the design, planning, and management of water resources. Given increasing evidence of trends in low-streamflow, new approaches to estimating low-streamflow statistics are needed. Here we investigate simple approaches to select a recent subset of the low-flow record to update the commonly used statistic of 7Q10, the annual minimum 7-day sAuthorsAnnalise G. Blum, Stacey A. Archfield, Robert M. Hirsch, Richard M Vogel, Julie E. Kiang, Robert W. DudleyPhosphorus and the Chesapeake Bay: Lingering issues and emerging concerns for agriculture
Hennig Brandt's discovery of phosphorus (P) occurred during the early European colonization of the Chesapeake Bay region. Today, P, an essential nutrient on land and water alike, is one of the principal threats to the health of the bay. Despite widespread implementation of best management practices across the Chesapeake Bay watershed following the implementation in 2010 of a total maximum daily loAuthorsPeter Kleinman, Rosemary M. Fanelli, Robert M. Hirsch, Anthony R Buda, Zachary M. Easton, Lisa A. Wainger, Chris Brosch, Mark Lowenfish, Amy S. Collick, Adel Shirmohammadi, Kathy Boomer, Jason A. Hubbart, R. B. Bryant, Gary ShenkTracking changes in nutrient delivery to western Lake Erie: Approaches to compensate for variability and trends in streamflow
Tracking changes in stream nutrient inputs to Lake Erie over multidecadal time scales depends on the use of statistical methods that can remove the influence of year-to-year variability of streamflow but also explicitly consider the influence of long-term trends in streamflow. The methods introduced in this paper include an extended version of Weighted Regressions on Time, Discharge, and Season (WAuthorsAnne F. Choquette, Robert M. Hirsch, Jennifer C. Murphy, L.T. Johnson, R. B. ConfesorThe 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 mitigation effortAuthorsChristine Rumsey, Matthew P. Miller, Gregory E. Schwarz, Robert M. Hirsch, David D. Susong - Software
EGRET
An R-package for the analysis of long-term changes in water quality and streamflow, including the water-quality method Weighted Regressions on Time, Discharge, and Season (WRTDS).dataRetrieval
The U.S. Geological Survey (USGS) developed an R package called dataRetrieval to help simplify the process of discovering and retrieving water quality sample data, streamflow, groundwater, and other data available from Federal hydrologic web services such as National Water Information Systems (NWIS), the EPA Water Quality Exchange (WQX) System, and the National Hydrologic Dataset via the Hydro-Ne