Rodney began his career with the USGS in 1992 as a student in the Nashville field office. Upon finishing his degree (Bachelor of Science, Civil / Environmental Engineering, Tennessee Technological University),
Rodney returned to the USGS and has worked on a variety projects and programs during his 28-year career. His early-career work included working with the Lower Tennessee River NAWQA team in a variety of roles as well as directing local projects with state partners on developing a program focused on ecological-flow analysis in the Tennessee River basin. These afforded him the opportunity to begin partnering with other states in the Lower Mississippi-Gulf footprint to bring USGS science interests to the table, particularly in the context of ecological flow. Through these efforts, the USGS has been funded through 2025 to evaluate freshwater inflows to the Gulf of Mexico across the 5 Gulf States and develop decision-support frameworks capable of incorporating ecological outcomes for 3 major river basins.
Along the way, Rodney collaborated with EPA Headquarters on the development of a Report to Congress, was an expert witness in a federal trial, and participated in a Powell Center workgroup focused on estimating water availability. Over the last several years, Rodney has enjoyed meeting with a variety of Federal, state, and local partners to develop partnerships and to help connect USGS science and data to real-world needs.
As Center Director for the Lower Mississippi-Gulf WSC, Rodney leads and manages a Center with almost 200 people on staff to provide high-quality water data, interpretations, and visualizations for federal, state, tribal, local and non-governmental agencies and further the mission of the USGS. Being a Director of a Center with a 5-state footprint (Alabama, Arkansas, Louisiana, Mississippi, and Tennessee) requires him to develop and maintain an understanding of the scientific interests and needs of partner agencies, quite often extending beyond that of a single partner agency. Many times, this affords the opportunity to bring together different agencies from neighboring states to focus on a topic of common interest.
Science and Products
An analysis of streamflow trends in the southern and southeastern US from 1950-2015
Species richness responses to water withdrawal scenarios and minimum flow levels: Evaluating presumptive standards in the Tennessee and Cumberland River basins
Copula theory as a generalized framework for flow-duration curve-based streamflow estimates in ungaged and partially gaged catchments
Prediction and inference of flow-duration curves using multi-output neural networks
Streamflow characteristics from modelled runoff time series: Importance of calibration criteria selection
Putting flow-ecology relationships into practice: A decision-support system to assess fish community response to water-management scenarios
Model calibration criteria for estimating ecological flow characteristics
Accelerating advances in continental domain hydrologic modeling
Evaluation of statistical and rainfall-runoff models for predicting historical daily streamflow time series in the Des Moines and Iowa River watersheds
Hydrologic data for the Obed River watershed, Tennessee
Ecological limit functions relating fish community response to hydrologic departures of the ecological flow regime in the Tennessee River basin, United States
Modelling ecological flow regime: an example from the Tennessee and Cumberland River basins
Non-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
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Tennessee FloodWatch
Streamflow Alteration Assessments to Support Bay and Estuary Restoration in Gulf States
Lower Tennessee River (LTEN) Basin Study
Water availability for ungauged rivers: an integrative, multi-model approach to estimate water availability at ungauged rivers across the United States
Environmental Flow Research in the Tennessee River Basin
Mississippi Delta Management Systems Evaluation Areas (MDMSEA)
Estimated quantiles of decadal flow-duration curves using selected probability distributions fit to no-flow fractions and L-moments predicted for streamgages and for pour points of level-12 hydrologic unit codes in the southeastern United States, 1950-201
Estimated daily mean streamflows for HUC12 pour points in the southeastern United States, 1950-2009
Observed and modeled daily streamflow values for 74 U.S. Geological Survey streamgage locations in the Trinity and Mobile-Tombigbee River basins in the Southeast United States: 2000--2009
Summary of basin characteristics for National Hydrography Dataset, version 2 catchments in the southeastern United States, 1950 - 2010
Heuristically-determined geospatial boundary of streams and rivers draining to the Gulf of Mexico in the south-central and southeastern United States, July 2018
Solar radiation for National Hydrography Dataset, version 2 catchments in the Southeastern United States: 1950 - 2010
Summary of streamflow statistics for USGS streamgages in the southeastern United States: 1950 - 2010
Geospatial data supporting assessments of streamflow alteration to support bay and estuary restoration in the Gulf States
Trend analysis results for sites used in RESTORE Streamflow alteration assessments
Streamflow and fish community diversity data for use in developing ecological limit functions for the Cumberland Plateau, northeastern Middle Tennessee and southwestern Kentucky, 2015
RESTORE/fdclmrpplo, Source code for estimation of L-moments and percent no-flow conditions for decadal flow-duration curves and estimation at level-12 hydrologic unit codes along with other statistical computations
Science and Products
- Publications
Filter Total Items: 22
An analysis of streamflow trends in the southern and southeastern US from 1950-2015
In this article, the mean daily streamflow at 139 streamflow-gaging stations (sites) in the southern and southeastern United States are analyzed for spatial and temporal patterns. One hundred and thirty-nine individual time-series of mean daily streamflow were reduced to five aggregated time series of Z scores for clusters of sites with similar temporal variability. These aggregated time-series coAuthorsKirk D. Rodgers, Victor L. Roland, Anne B. Hoos, Elena Crowley-Ornelas, Rodney KnightSpecies richness responses to water withdrawal scenarios and minimum flow levels: Evaluating presumptive standards in the Tennessee and Cumberland River basins
Water resource managers are challenged to balance growing water demand with protecting aquatic ecosystems and biodiversity. Management decisions can benefit from improved understanding of water withdrawal impacts on hydrologic regimes and ecological assemblages. This study used Ecological Limit Functions for fish groups within the Tennessee and Cumberland river basins to predict species richness rAuthorsLucas Driver, Jennifer M. Cartwright, Rodney Knight, William J. WolfeCopula theory as a generalized framework for flow-duration curve-based streamflow estimates in ungaged and partially gaged catchments
Flow‐duration curve (FDC) based streamflow estimation methods involve estimating an FDC at an ungaged or partially gaged location and using the time series of nonexceedance probabilities estimated from donor streamgage sites to generate estimates of streamflow. We develop a mathematical framework to illustrate the connection between copulas and prior FDC‐based approaches. The performance of copulaAuthorsScott C. Worland, Scott Steinschneider, William H. Farmer, William H. Asquith, Rodney WhitePrediction and inference of flow-duration curves using multi-output neural networks
We develop multi-output neural network models (MNNs) to predict flow-duration curves (FDCs) in 9,203 ungaged locations in the Southeastern United States for six decades between 1950-2009. The model architecture contains multiple response variables in the output layer that correspond to individual quantiles along the FDC. During training, predictions are made for each quantile, and a combined lossAuthorsScott C. Worland, Scott Steinschneider, William H. Asquith, Rodney Knight, Michael E. WieczorekStreamflow characteristics from modelled runoff time series: Importance of calibration criteria selection
Ecologically relevant streamflow characteristics (SFCs) of ungauged catchments are often estimated from simulated runoff of hydrologic models that were originally calibrated on gauged catchments. However, SFC estimates of the gauged donor catchments and subsequently the ungauged catchments can be substantially uncertain when models are calibrated using traditional approaches based on optimizationAuthorsSandra Poole, Marc Vis, Rodney Knight, Jan SeibertPutting flow-ecology relationships into practice: A decision-support system to assess fish community response to water-management scenarios
This paper presents a conceptual framework to operationalize flow–ecology relationships into decision-support systems of practical use to water-resource managers, who are commonly tasked with balancing multiple competing socioeconomic and environmental priorities. We illustrate this framework with a case study, whereby fish community responses to various water-management scenarios were predicted iAuthorsJennifer M. Cartwright, Casey Caldwell, Steven Nebiker, Rodney KnightModel calibration criteria for estimating ecological flow characteristics
Quantification of streamflow characteristics in ungauged catchments remains a challenge. Hydrological modeling is often used to derive flow time series and to calculate streamflow characteristics for subsequent applications that may differ from those envisioned by the modelers. While the estimation of model parameters for ungauged catchments is a challenging research task in itself, it is importanAuthorsMarc Vis, Rodney Knight, Sandra Poole, William J. Wolfe, Jan SeibertAccelerating advances in continental domain hydrologic modeling
In the past, hydrologic modeling of surface water resources has mainly focused on simulating the hydrologic cycle at local to regional catchment modeling domains. There now exists a level of maturity among the catchment, global water security, and land surface modeling communities such that these communities are converging toward continental domain hydrologic models. This commentary, written fromAuthorsStacey A. Archfield, Martyn Clark, Berit Arheimer, Lauren E. Hay, Hilary McMillan, Julie E. Kiang, Jan Seibert, Kirsti Hakala, Andrew R. Bock, Thorsten Wagener, William H. Farmer, Vazken Andreassian, Sabine Attinger, Alberto Viglione, Rodney Knight, Steven L. Markstrom, Thomas M. OverEvaluation of statistical and rainfall-runoff models for predicting historical daily streamflow time series in the Des Moines and Iowa River watersheds
Daily records of streamflow are essential to understanding hydrologic systems and managing the interactions between human and natural systems. Many watersheds and locations lack streamgages to provide accurate and reliable records of daily streamflow. In such ungaged watersheds, statistical tools and rainfall-runoff models are used to estimate daily streamflow. Previous work compared 19 differentAuthorsWilliam H. Farmer, Rodney R. Knight, David A. Eash, Kasey J. Hutchinson, S. Mike Linhart, Daniel E. Christiansen, Stacey A. Archfield, Thomas M. Over, Julie E. KiangHydrologic data for the Obed River watershed, Tennessee
The Obed River watershed drains a 520-square-mile area of the Cumberland Plateau physiographic region in the Tennessee River basin. The watershed is underlain by conglomerate, sandstone, and shale of Pennsylvanian age, which overlie Mississippian-age limestone. The larger creeks and rivers of the Obed River system have eroded gorges through the conglomerate and sandstone into the deeper shale. TheAuthorsRodney R. Knight, William J. Wolfe, George S. LawEcological limit functions relating fish community response to hydrologic departures of the ecological flow regime in the Tennessee River basin, United States
Ecological limit functions relating streamflow and aquatic ecosystems remain elusive despite decades of research. We investigated functional relationships between species richness and changes in streamflow characteristics at 662 fish sampling sites in the Tennessee River basin. Our approach included the following: (1) a brief summary of relevant literature on functional relations between fish andAuthorsRodney R. Knight, Jennifer C. Murphy, William J. Wolfe, Charles F. Saylor, Amy K. WalesModelling ecological flow regime: an example from the Tennessee and Cumberland River basins
Predictive equations were developed for 19 ecologically relevant streamflow characteristics within five major groups of flow variables (magnitude, ratio, frequency, variability, and date) for use in the Tennessee and Cumberland River basins using stepbackward regression. Basin characteristics explain 50% or more of the variation for 12 of the 19 equations. Independent variables identified throughAuthorsRodney R. Knight, W. Scott Gain, William J. WolfeNon-USGS Publications**
Murphy, J. C., Knight, R. R., Wolfe, W. J. and Gain, W.S. (2013), Predicting Ecological Flow Regime at Ungaged Sites: A Comparison of Methods. River Research and Applications, 29: 660–669. doi: 10.1002/rra.2570Rodgers, K.D., Breaker, B.K., Hart, R.M., and Knight, R.R., 2017, Geospatial data supporting assessments of streamflow alteration to support bay and estuary restoration in the Gulf States: U.S. Geological Survey data release, https://doi.org/10.5066/F7QF8R33**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
- Science
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Tennessee FloodWatch
Tennessee FloodWatch InformationStreamflow Alteration Assessments to Support Bay and Estuary Restoration in Gulf States
Human alteration of waterways has impacted the minimum and maximum streamflows in more than 86% of monitored streams nationally and may be the primary cause for ecological impairment in river and stream ecosystems. Restoration of freshwater inflows can positively affect shellfish, fisheries, habitat, and water quality in streams, rivers, and estuaries. Increasingly, state and local decision-makers...Lower Tennessee River (LTEN) Basin Study
Welcome....the Lower Tennessee River Basin in Tennessee, Alabama, Georgia, Kentucky, and Mississippi is one of the 59 study units that are part of the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program.The long-term goals of this program are to describe the status and trends in the quality of a large, representative part of the Nation's surface- and ground-water resources...Water availability for ungauged rivers: an integrative, multi-model approach to estimate water availability at ungauged rivers across the United States
There has been increasing attention placed on the need for water availability information at ungauged locations, particularly related to balancing human and ecological needs for water. Critical to assessing water availability is the necessity for daily streamflow time series; however, most of the rivers in the United States are ungauged. This proposal leverages over $1M currently allocated to theEnvironmental Flow Research in the Tennessee River Basin
The objective of this project is to improve understanding of how alteration of streamflow characteristics affects the ecological health of rivers and streams in Tennessee. Initial efforts are aimed at identifying critical streamflow characteristics and providing a set of statistical tools and analytical approaches for the prediction of these characteristics. Application of these tools will enhance...Mississippi Delta Management Systems Evaluation Areas (MDMSEA)
The Mississippi Delta Management Systems Evaluation Areas (MDMSEA) Project began in 1995 with two purposes: 1) to assess how agricultural activities affect water quality; and 2) to evaluate Best Management Practices (BMPs) that mitigate agricultural nonpoint source pollution. The project is located in the northwestern portion of Mississippi, an area of intense agriculture referred to as the... - Data
Estimated quantiles of decadal flow-duration curves using selected probability distributions fit to no-flow fractions and L-moments predicted for streamgages and for pour points of level-12 hydrologic unit codes in the southeastern United States, 1950-201
Using previously published (Robinson and others, 2019) no-flow fractions and L-moments of nonzero streamflow from decadal streamflow flow-duration analysis (daily mean streamflow), probability distributions were fit to provide 27 estimated quantiles of decadal flow-duration curves, and hence the probability distributions are a form of parametric modeling that ensures monotonicity of the quantilesEstimated daily mean streamflows for HUC12 pour points in the southeastern United States, 1950-2009
This data release contains estimated daily streamflow values for 9,203 12-digit hydrologic unit codes (HUC12s) in the southeastern United States for the period 1950-2009. The files are provided in text format, which can be used in R and in other programs. The 'Site Info' folder contains 18 files with streamgage information and the 'Daily Values' folder contains 18 files with predicted daily streaObserved and modeled daily streamflow values for 74 U.S. Geological Survey streamgage locations in the Trinity and Mobile-Tombigbee River basins in the Southeast United States: 2000--2009
The data and R scripts contained in this data release are provided as support for a manuscript titled, "Copula theory as a generalized framework for flow-duration curve based streamflow estimates in ungaged and partially gaged catchments" (Worland and others, 2019) submitted to Water Resources Research. The dv_input.csv contains the measured daily streamflow values for 37 streamgages in the MobileSummary of basin characteristics for National Hydrography Dataset, version 2 catchments in the southeastern United States, 1950 - 2010
This dataset provides numerical and categorical descriptions of 46 basin characteristics for 957 basins with observed streamflow information and 9,314 ungaged basins coinciding with 12-digit hydrologic unit code pour points that drain to the Gulf of Mexico. Characteristics are indexed by National Hydrography Dataset (NHD) version 2 COMID and USGS site number (streamflow-gaging station), where appHeuristically-determined geospatial boundary of streams and rivers draining to the Gulf of Mexico in the south-central and southeastern United States, July 2018
Human alteration of waterways has impacted the minimum and maximum streamflow in more than 86% of monitored streams nationally and may be the primary cause for ecological impairment in river and stream ecosystems. Restoration of freshwater inflows can positively affect shellfish, fisheries, habitat, and water quality in streams, rivers, and estuaries. Increasingly, state and local decision-makersSolar radiation for National Hydrography Dataset, version 2 catchments in the Southeastern United States: 1950 - 2010
This study is based on contiguous direct normal irradiance information from the National Renewable Energy Laboratory. Specifically, these data represent both 12-month specific average and annual average daily total solar resource averaged over surface cells of 0.1 degrees in both latitude and longitude. Spacing is about 10 kilometers in size. Direct normal irradiance is the amount of solar radiatiSummary of streamflow statistics for USGS streamgages in the southeastern United States: 1950 - 2010
This dataset contains statistical descriptions of observed daily-mean streamflow for 956 sites in the southeast United States. For each site, statistical descriptions are provided according to decade for up to six decades, beginning in 1950 (1950-59 calendar years) and ending with 2000 (2000 - 2009 calendar years) with no more than 7 missing values per year in total (continuous or noncontinuous).Geospatial data supporting assessments of streamflow alteration to support bay and estuary restoration in the Gulf States
The state-of-the-science for implementing restoration of flows for freshwater and estuarine ecosystems health has improved markedly. Many successful examples now exist for improving the timing and delivery of freshwater flows through collaborative processes such as modification of flow regimes through operational changes made through dam re-regulation, dam removal, conservation and efficiency, imTrend analysis results for sites used in RESTORE Streamflow alteration assessments
Daily streamflow discharge data from 139 streamgages located on tributaries and streams flowing to the Gulf of Mexico were used to calculate mean monthly, mean seasonal, and decile values. Streamgages used to calculate trends required a minimum of 65 years of continuous daily streamflow data. These values were used to analyze trends in streamflow using the Mann-Kendall trend test in the R packageStreamflow and fish community diversity data for use in developing ecological limit functions for the Cumberland Plateau, northeastern Middle Tennessee and southwestern Kentucky, 2015
This geospatial dataset includes one point feature class file and associated FGDC-compliant metadata representing datasets to support development of ecological limit functions for the Cumberland Plateau in northeastern Middle Tennessee and southeastern Kentucky. Information contained within the dataset represents values of basin characteristics, estimates of streamflow characteristics, measures o - Software
RESTORE/fdclmrpplo, Source code for estimation of L-moments and percent no-flow conditions for decadal flow-duration curves and estimation at level-12 hydrologic unit codes along with other statistical computations
The RESTORE/fdclmrpplo repository contains R language source code used for estimation of the L-moments and percent no-flow conditions (no-flow fractions) for decadal flow-duration curves and estimation at streamgages and level-12 hydrologic unit codes using generalized additive models and censored generalized additive models. The source code is designed to streamline the workflow for the Gulf Coas - Multimedia