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
Peak-streamflow trends and change-points and basin characteristics for 2,683 U.S. Geological Survey streamgages in the conterminous U.S.
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
Data Documenting the U.S. Geological Survey Peak-Flow File Data Verification Project, 2008-16
Total Phosphorus Load and Ancillary Data Related to Sources of Total Phosphorus in the Red River of the North Basin
Historical and paleoflood analyses for probabilistic flood-hazard assessments—Approaches and review guidelines
Climate extremes as drivers of surface-water-quality trends in the United States
Statistical methods in water resources
Flood-frequency estimation for very low annual exceedance probabilities using historical, paleoflood, and regional information with consideration of nonstationarity
seawaveQ—An R package providing 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, version 2.0.0
Landscape drivers of dynamic change in water quality of US rivers
Causal effect of impervious cover on annual flood magnitude for the United States
Causal factors for pesticide trends in streams of the United States: Atrazine and deethylatrazine
Change points in annual peak streamflows: Method comparisons and historical change points in the United States
Modeling drivers of phosphorus loads in Chesapeake Bay tributaries and inferences about long-term change
The U.S. Geological Survey Peak-Flow File Data Verification Project, 2008–16
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
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 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: 41
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 dClimate 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 tStatistical 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 tFlood-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 stseawaveQ—An R package providing 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, version 2.0.0
The seawaveQ R package provides functionality and help to fit a parametric regression model, SEAWAVE-Q, to pesticide concentration data from stream-water samples to assess trends. The model incorporates the strong seasonality and high degree of censoring common in pesticide data, and users can incorporate numerous ancillary variables such as streamflow anomalies. The model is fitted to pesticide dLandscape drivers of dynamic change in water quality of US rivers
Water security is a top concern for social well-being and dramatic changes in the availability of freshwater have occurred as a result of human uses and landscape management. Elevated nutrient loading and perturbations to major ion composition have resulted from human activities and have degraded freshwater resources. This study addresses the emerging nature of stream water quality in the 21st ceCausal effect of impervious cover on annual flood magnitude for the United States
Despite consensus that impervious surfaces increase flooding, the magnitude of the increase remains uncertain. This uncertainty largely stems from the challenge of isolating the effect of changes in impervious cover separate from other factors that also affect flooding. To control for these factors, prior study designs rely on either temporal or spatial variation in impervious cover. We leverage bCausal factors for pesticide trends in streams of the United States: Atrazine and deethylatrazine
Pesticides are important for agriculture in the United States, and atrazine is one of the most widely used and widely detected pesticides in surface water. A better understanding of the mechanisms by which atrazine and its degradation product, deethylatrazine, increase and decrease in surface waters can help inform future decisions for water-quality improvement. This study considers causal factorsChange 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. ThisModeling drivers of phosphorus loads in Chesapeake Bay tributaries and inferences about long-term change
Causal attribution of changes in water quality often consists of correlation, qualitative reasoning, listing references to the work of others, or speculation. To better support statements of attribution for water-quality trends, structural equation modeling was used to model the causal factors of total phosphorus loads in the Chesapeake Bay watershed. By transforming, scaling, and standardizing vaThe U.S. Geological Survey Peak-Flow File Data Verification Project, 2008–16
Annual peak streamflow (peak flow) at a streamgage is defined as the maximum instantaneous flow in a water year. A water year begins on October 1 and continues through September 30 of the following year; for example, water year 2015 extends from October 1, 2014, through September 30, 2015. The accuracy, characterization, and completeness of the peak streamflow data are critical in determining floo - News