Research Statistician for the Dakota Water Science Center
Expertise/Projects/Research Interests
- Statistical analysis of hydrologic data, including parametric and nonparametric trend analysis and cluster analysis
- Trend analysis for pesticide concentrations in surface water
- Research related to the impact of climate variability on surface water
- Data mining including automated data retrieval and analysis, outlier detection, and data cleaning
- Machine learning
- Graphical presentation of scientific data
- R - Open Source Statistical Software
- waterData package - Retrieval, analysis, and anomaly calculation of daily hydrologic time series data
- seawaveQ package - A model and utilities for analyzing trends in chemical concentrations in streams with a seasonal wave (seawave) and adjustment for streamflow (Q) and other ancillary variables
- Associate Editor, Hydrological Sciences Journal
- Course Coordinator and member of team teaching Statistical Methods for Environmental Data Analysis at USGS National Training Center
Publications
Ryberg, K.R., 2021, The role of the U.S. Geological Survey in monitoring North Dakota’s environmental conditions: North Dakota Climate Bulletin, v. 15, no. 1, p. 11–14, https://www.ndsu.edu/ndsco/climatesummaries/quarterlyclimatebulletin/.
Helsel, D.R., Hirsch, R.M., Ryberg, K.R., Archfield, S.A., and Gilroy, E.J., 2020, Statistical methods in water resources: U.S. Geological Survey Techniques and Methods, book 4, chapter A3, 458 p., https://doi.org/10.3133/tm4a3. [Supersedes USGS Techniques of Water-Resources Investigat
Education and Certifications
Doctorate of Philosophy, Environmental and Conservation Sciences - Environmental Science Track, 2015 North Dakota State University, Fargo, North Dakota
Dissertation: The impact of climate variability
Master of Science, Statistics, 2006, Colorado State University, Fort Collins, Colorado
Masters Project: Water-quality trend analysis for the Devils Lake Basin, North Dakota, January 1965 through Sept
Associate of Applied Science, Computer Support Specialist, 2003 Bismarck State College, Bismarck, North Dakota
Bachelor of Arts, Mathematics, 1995 Luther College, Decorah, Iowa
Mathematics for Machine Learning Specialization Certificate— Imperial College London on Coursera, 2020
Facilitator Training—Learning to Lead Reflective Conversations, an educational program of Humanities North Dakota and Bismarck State College, Bismarck, ND., 2018
Specialization Certificate in Executive Data Science— Johns Hopkins University on Coursera, 2018
Graduate Certificate, Data Mining and Applications, 2008, Stanford University, Stanford, California
Management, 1996, University of Mary, Bismarck, North Dakota
Science and Products
Flood-Frequency Analysis in the Midwest: Addressing Potential Nonstationary Annual Peak-Flow Records
Period of Project: 2021 -Study Area: MidwestCooperating Agency: Transportation Pooled Fund
Data from Assessing the added value of antecedent streamflow alteration in modelling stream condition
The dataset contains long-term and short-term summaries of streamflow alteration and measures of biological condition (fish multi-metric index). Streamflow alteration metrics include the magnitude, duration, frequency, and seasonality of high and low flow streamflow. Biological condition was estimated from the National Rivers and Streams Assessment and National Water Quality Assessment fish sampli
Data for simulation experiments comparing nonstationary design-flood adjustments based on observed annual peak flows in the conterminous United States
This dataset contains files used in this Monte Carlo simulation study comparing the performance of five statistical models for adjusting design floods for current conditions at sites with known trends. These files include (i) the observed annual peak-flow series in the conterminous US used to inform ranges of known moments and trends used in the simulation experiment, (ii) the 3,000 combinations o
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
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
Daily streamflow datasets used to analyze trends in streamflow at sites also analyzed for trends in water quality and ecological condition in the Nation's rivers and streams
In 1991, the U.S. Geological Survey (USGS) began a study of more than 50 major river basins across the Nation as part of the National Water-Quality Assessment (NAWQA) project of the National Water-Quality Program. One of the major goals of the NAWQA project is to determine how water-quality conditions change over time. To support that goal, long-term consistent and comparable monitoring has been c
Data Documenting the U.S. Geological Survey Peak-Flow File Data Verification Project, 2008-16
These data provide a public summary of the changes made to the U.S. Geological Survey peak-flow file since formal Nation-wide checking began in 2008. Coverage includes peak-flow sites in the United States and territories.
Total Phosphorus Load and Ancillary Data Related to Sources of Total Phosphorus in the Red River of the North Basin
The Red River of the North (Red River) transports phosphorus from North Dakota, Minnesota, and South Dakota, to Manitoba, Canada, and eventually into Lake Winnipeg. Phosphorus load (or flux) is the amount of total phosphorus (TP) transported by the Red River. The effect of TP load on water quality is a concern, especially with respect to downstream eutrophication issues in Lake Winnipeg, Manitob
Filter Total Items: 48
Assessing the added value of antecedent streamflow alteration information in modeling stream biological condition
In stream systems, disentangling relationships between biology and flow and subsequent prediction of these relationships to unsampled streams is a common objective of large-scale ecological modeling. Often, streamflow metrics are derived from aggregating continuous streamflow records available at a subset of stream gages into long-term flow regime descriptors. Despite demonstrated value, shortcomi
Authors
Taylor E Woods, Ken Eng, Daren Carlisle, Matt J. Cashman, Michael Meador, Karen R. Ryberg, Kelly O. Maloney
Method for identification of reservoir regulation within U.S. Geological Survey streamgage basins in the Central United States using a decadal dam impact metric
Researchers routinely study streamflow data to understand the effects of natural climate variability and anthropogenic climate change, and to develop methods for estimating streamflow at ungaged locations. These studies require streamflow data that are not modified or largely altered by other anthropogenic activities, such as reservoirs or diversions. This report discusses a method for identifying
Authors
Mackenzie K. Marti, Karen R. Ryberg
Flood-frequency analysis in the Midwest: Addressing potential nonstationarity of annual peak-flow records
Flood-frequency analysis is essential in numerous water-resource management applications, including critical structure design and flood-plain mapping. A basic assumption within Bulletin 17C [1], the standardized guidelines for conducting flood-frequency analysis, is that basins without major hydrologic alterations, such as regulation or urbanization, exhibit stationary statistical properties of th
Authors
Mackenzie K. Marti, Karen R. Ryberg, Sara B. Levin
Simulation experiments comparing nonstationary design-flood adjustments based on observed annual peak flows in the conterminous United States
While nonstationary flood frequency analysis (NSFFA) methods have proliferated, few studies have rigorously compared them for modeling changes in both the central tendency and variability of annual peak-flow series, also known as the annual maximum series (AMS), in hydrologically diverse areas. Through Monte Carlo experiments, we appraise five methods for updating estimates of 10- and 100-year flo
Authors
Jory Seth Hecht, Nancy A. Barth, Karen R. Ryberg, Angela Gregory
Attribution of monotonic trends and change points in peak streamflow across the conterminous United States using a multiple working hypotheses framework, 1941–2015 and 1966–2015
The U.S. Geological Survey has a long history of leading flood-frequency analysis studies. These studies play a critical role in the assessment of risk, protection of lives, and planning and design of flood protection infrastructure. Standard flood-frequency analysis is based on the assumption of stationarity—that is, that the distribution of floods at a given site varies around a particular mean
Projecting flood frequency curves under near-term climate change
Flood-frequency curves, critical for water infrastructure design, are typically developed based on a stationary climate assumption. However, climate changes are expected to violate this assumption. Here, we propose a new, climate-informed methodology for estimating flood-frequency curves under non-stationary future climate conditions. The methodology develops an asynchronous, semiparametric local-
Authors
Chandramauli Awasthi, Stacey A. Archfield, Karen R. Ryberg, Julie E. Kiang, A. Sankarasubramanian
Assessment of streamflow trends in the eastern Dakotas, water years 1960–2019
Hydrologic extremes, whether periods of drought or flooding, are occurring more frequently with greater severity and can have substantial economic impacts. Along with flooding, the timing and volume of streamflow also is changing across the United States. The focus of this report is to characterize a unique trend in mean annual streamflow occurring in eastern North and South Dakota, hereafter refe
Authors
Parker A. Norton, Gregory C. Delzer, Joshua F. Valder, Wyatt S. Tatge, Karen R. Ryberg
Historical and paleoflood analyses for probabilistic flood-hazard assessments—Approaches and review guidelines
Paleoflood studies are an effective means of providing specific information on the recurrence and magnitude of rare and large floods. Such information can be combined with systematic flood measurements to better assess the frequency of large floods. Paleoflood data also provide valuable information about the linkages among climate, land use, flood-hazard assessments, and channel morphology. This d
Authors
Tessa M. Harden, Karen R. Ryberg, Jim E. O'Connor, Jonathan M. Friedman, Julie E. Kiang
Climate extremes as drivers of surface-water-quality trends in the United States
Surface-water quality can change in response to climate perturbations, such as changes in the frequency of heavy precipitation or droughts, through direct effects, such as dilution and concentration, and through physical processes, such as bank scour. Water quality might also change through indirect mechanisms, such as changing water demand or changes in runoff interaction with organic matter on t
Authors
Karen R. Ryberg, Jeffrey G. Chanat
The role of the U.S. Geological Survey in monitoring North Dakota’s environmental conditions
No abstract available.
Authors
Karen R. Ryberg
Statistical 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 t
Authors
Dennis R. Helsel, Robert M. Hirsch, Karen R. Ryberg, Stacey A. Archfield, Edward J. Gilroy
Flood-frequency estimation for very low annual exceedance probabilities using historical, paleoflood, and regional information with consideration of nonstationarity
Streamflow estimates for floods with an annual exceedance probability of 0.001 or lower are needed to accurately portray risks to critical infrastructure, such as nuclear powerplants and large dams. However, extrapolating flood-frequency curves developed from at-site systematic streamflow records to very low annual exceedance probabilities (less than 0.001) results in large uncertainties in the st
Authors
Karen R. Ryberg, Kelsey A. Kolars, Julie E. Kiang, Meredith L. Carr
Science and Products
- Science
Flood-Frequency Analysis in the Midwest: Addressing Potential Nonstationary Annual Peak-Flow Records
Period of Project: 2021 -Study Area: MidwestCooperating Agency: Transportation Pooled Fund - Data
Data from Assessing the added value of antecedent streamflow alteration in modelling stream condition
The dataset contains long-term and short-term summaries of streamflow alteration and measures of biological condition (fish multi-metric index). Streamflow alteration metrics include the magnitude, duration, frequency, and seasonality of high and low flow streamflow. Biological condition was estimated from the National Rivers and Streams Assessment and National Water Quality Assessment fish sampliData for simulation experiments comparing nonstationary design-flood adjustments based on observed annual peak flows in the conterminous United States
This dataset contains files used in this Monte Carlo simulation study comparing the performance of five statistical models for adjusting design floods for current conditions at sites with known trends. These files include (i) the observed annual peak-flow series in the conterminous US used to inform ranges of known moments and trends used in the simulation experiment, (ii) the 3,000 combinations oAttributions 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 waPeak-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 slopDaily streamflow datasets used to analyze trends in streamflow at sites also analyzed for trends in water quality and ecological condition in the Nation's rivers and streams
In 1991, the U.S. Geological Survey (USGS) began a study of more than 50 major river basins across the Nation as part of the National Water-Quality Assessment (NAWQA) project of the National Water-Quality Program. One of the major goals of the NAWQA project is to determine how water-quality conditions change over time. To support that goal, long-term consistent and comparable monitoring has been cData Documenting the U.S. Geological Survey Peak-Flow File Data Verification Project, 2008-16
These data provide a public summary of the changes made to the U.S. Geological Survey peak-flow file since formal Nation-wide checking began in 2008. Coverage includes peak-flow sites in the United States and territories.Total Phosphorus Load and Ancillary Data Related to Sources of Total Phosphorus in the Red River of the North Basin
The Red River of the North (Red River) transports phosphorus from North Dakota, Minnesota, and South Dakota, to Manitoba, Canada, and eventually into Lake Winnipeg. Phosphorus load (or flux) is the amount of total phosphorus (TP) transported by the Red River. The effect of TP load on water quality is a concern, especially with respect to downstream eutrophication issues in Lake Winnipeg, Manitob - Multimedia
- Publications
Filter Total Items: 48
Assessing the added value of antecedent streamflow alteration information in modeling stream biological condition
In stream systems, disentangling relationships between biology and flow and subsequent prediction of these relationships to unsampled streams is a common objective of large-scale ecological modeling. Often, streamflow metrics are derived from aggregating continuous streamflow records available at a subset of stream gages into long-term flow regime descriptors. Despite demonstrated value, shortcomiAuthorsTaylor E Woods, Ken Eng, Daren Carlisle, Matt J. Cashman, Michael Meador, Karen R. Ryberg, Kelly O. MaloneyMethod for identification of reservoir regulation within U.S. Geological Survey streamgage basins in the Central United States using a decadal dam impact metric
Researchers routinely study streamflow data to understand the effects of natural climate variability and anthropogenic climate change, and to develop methods for estimating streamflow at ungaged locations. These studies require streamflow data that are not modified or largely altered by other anthropogenic activities, such as reservoirs or diversions. This report discusses a method for identifyingAuthorsMackenzie K. Marti, Karen R. RybergFlood-frequency analysis in the Midwest: Addressing potential nonstationarity of annual peak-flow records
Flood-frequency analysis is essential in numerous water-resource management applications, including critical structure design and flood-plain mapping. A basic assumption within Bulletin 17C [1], the standardized guidelines for conducting flood-frequency analysis, is that basins without major hydrologic alterations, such as regulation or urbanization, exhibit stationary statistical properties of thAuthorsMackenzie K. Marti, Karen R. Ryberg, Sara B. LevinSimulation experiments comparing nonstationary design-flood adjustments based on observed annual peak flows in the conterminous United States
While nonstationary flood frequency analysis (NSFFA) methods have proliferated, few studies have rigorously compared them for modeling changes in both the central tendency and variability of annual peak-flow series, also known as the annual maximum series (AMS), in hydrologically diverse areas. Through Monte Carlo experiments, we appraise five methods for updating estimates of 10- and 100-year floAuthorsJory Seth Hecht, Nancy A. Barth, Karen R. Ryberg, Angela GregoryAttribution of monotonic trends and change points in peak streamflow across the conterminous United States using a multiple working hypotheses framework, 1941–2015 and 1966–2015
The U.S. Geological Survey has a long history of leading flood-frequency analysis studies. These studies play a critical role in the assessment of risk, protection of lives, and planning and design of flood protection infrastructure. Standard flood-frequency analysis is based on the assumption of stationarity—that is, that the distribution of floods at a given site varies around a particular meanProjecting flood frequency curves under near-term climate change
Flood-frequency curves, critical for water infrastructure design, are typically developed based on a stationary climate assumption. However, climate changes are expected to violate this assumption. Here, we propose a new, climate-informed methodology for estimating flood-frequency curves under non-stationary future climate conditions. The methodology develops an asynchronous, semiparametric local-AuthorsChandramauli Awasthi, Stacey A. Archfield, Karen R. Ryberg, Julie E. Kiang, A. SankarasubramanianAssessment of streamflow trends in the eastern Dakotas, water years 1960–2019
Hydrologic extremes, whether periods of drought or flooding, are occurring more frequently with greater severity and can have substantial economic impacts. Along with flooding, the timing and volume of streamflow also is changing across the United States. The focus of this report is to characterize a unique trend in mean annual streamflow occurring in eastern North and South Dakota, hereafter refeAuthorsParker A. Norton, Gregory C. Delzer, Joshua F. Valder, Wyatt S. Tatge, Karen R. RybergHistorical and paleoflood analyses for probabilistic flood-hazard assessments—Approaches and review guidelines
Paleoflood studies are an effective means of providing specific information on the recurrence and magnitude of rare and large floods. Such information can be combined with systematic flood measurements to better assess the frequency of large floods. Paleoflood data also provide valuable information about the linkages among climate, land use, flood-hazard assessments, and channel morphology. This dAuthorsTessa M. Harden, Karen R. Ryberg, Jim E. O'Connor, Jonathan M. Friedman, Julie E. KiangClimate extremes as drivers of surface-water-quality trends in the United States
Surface-water quality can change in response to climate perturbations, such as changes in the frequency of heavy precipitation or droughts, through direct effects, such as dilution and concentration, and through physical processes, such as bank scour. Water quality might also change through indirect mechanisms, such as changing water demand or changes in runoff interaction with organic matter on tAuthorsKaren R. Ryberg, Jeffrey G. ChanatThe role of the U.S. Geological Survey in monitoring North Dakota’s environmental conditions
No abstract available.AuthorsKaren R. RybergStatistical 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. GilroyFlood-frequency estimation for very low annual exceedance probabilities using historical, paleoflood, and regional information with consideration of nonstationarity
Streamflow estimates for floods with an annual exceedance probability of 0.001 or lower are needed to accurately portray risks to critical infrastructure, such as nuclear powerplants and large dams. However, extrapolating flood-frequency curves developed from at-site systematic streamflow records to very low annual exceedance probabilities (less than 0.001) results in large uncertainties in the stAuthorsKaren R. Ryberg, Kelsey A. Kolars, Julie E. Kiang, Meredith L. Carr - News