Flood-frequency analyses were conducted for three streamgages operated by the U.S. Geological Survey (USGS) in the Black River basin of southeastern Missouri (MO) and northeastern Arkansas (AR): 07064000, Black River near Corning, AR; 07068000, Current River at Doniphan, MO; and 07069000, Black River at Pocahontas, AR. Results from the analyses will be used for design purposes by the Arkansas Department of Transportation in the future Interstate 57 alignment from Walnut Ridge, AR to the MO state line. Annual peak-flow data through the 2023 water year (a water year is defined as the period October 1 - September 30, named for the year in which it ends) were downloaded from the USGS National Water Information System (NWIS) website at https://nwis.waterdata.usgs.gov/nwis/peak. Flood-frequency analyses using the Expected Moments Algorithm (EMA) were conducted in version 7.5.1 of USGS PeakFQ software (Veilleux and others, 2014; Flynn and others, 2006) following federal guidelines (England and others, 2019) and the techniques outlined in the most recent USGS flood-frequency report for Arkansas (Wagner and others, 2016). Peak-flow (.pkf), specification (.psf), output (.PRT) and export (.EXP) files from PeakFQ are provided, in addition to a plot of the frequency curve for each streamgage in .PNG format. Results from the flood-frequency analyses, including estimates of the magnitudes of floods corresponding to the 0.5, 0.2, 0.1, 0.04, 0.02, 0.01, 0.005, and 0.002 annual exceedance probabilities (AEPs; the equivalent of the 2-, 5-, 10-, 25-, 50-, 100-, 200-, and 500-year recurrence intervals, respectively) and their associated variances and confidence intervals were retrieved from the .PRT file and are provided in .csv format.

This dataset contains site information and results of flood-frequency analysis for 422 streamflow gaging stations (streamgages) operated by the U.S. Geological Survey (USGS) in parts of the Upper Mississippi and Souris-Red-Rainy basins and surrounding areas in the United States. Annual peak-flow data from the 1844 - 2013 water years were used in the study (U.S. Geological Survey, 2024). Following federal guidelines for flood-frequency analysis (Bulletin 17C; England and others, 2018) and methods outlined in recent flood-frequency reports for the region (Eash and others, 2013; Southard and Veilleux, 2014; Levin and Sanocki, 2023; Sanocki and Levin, 2023), the Expected Moments Algorithm (EMA) was used in version 7.5.1 of USGS PeakFQ software (Veilleux and others, 2014; Flynn and others, 2006; https://water.ugsgs.gov/software/PeakFQ/) to conduct the analyses. Results of the analyses, specifically the at-site skew and its mean squared error, are intended for use in Bayesian weighted least-squares/Bayesian generalized least-squares (B-WLS/B-GLS) regression (Veilleux and Wagner, 2019; Veilleux and Wagner, 2021) to model regional skew for the study area. Peak-flow (.pkf), specification (.psf), output (.PRT), and export (.EXP) files from PeakFQ and a .csv file containing site information and selected results of flood-frequency analyses are provided.

This dataset contains site information, basin characteristics, results of flood-frequency analysis, and a generalized (regional) flood skew for 76 selected streamgages operated by the U.S. Geological Survey (USGS) in the upper White River basin (4-digit hydrologic unit 1101) in southern Missouri and northern Arkansas. The Little Rock District U.S. Army Corps of Engineers (USACE) needed updated estimates of streamflows corresponding to selected annual exceedance probabilities (AEPs) and a basin-specific regional flood skew. USGS selected 111 candidate streamgages in the study area that had 20 or more years of gaged annual peak-flow data available through the 2020 water year. After screening for regulation, urbanization, redundant/nested basins, drainage areas greater than 2,500 square miles, and streamgage basins located in the Mississippi Alluvial Plain (8-digit hydrologic unit 11010013), 77 candidate streamgages remained. After conducting the initial flood-frequency analysis to generate at-site (station) skew and its mean squared error (MSE) for development of the regional flood skew, four streamgages with less than 20 years of pseudo effective record length (PRL) and two streamgages with an excessive amount of censored annual peak flows were removed, leaving 71 streamgages (44 in Arkansas and 27 in Missouri) for use in the study. Flood-frequency analysis was done using the Expected Moments Algorithm (EMA) in version 7.3 of USGS software PeakFQ (Veilleux and others, 2014; England and others, 2019). Ten basin characteristics were tested as explanatory variables in a generalized additive model (GAM) of flood skew, but a lack of statistical significance of the variables, including two-dimensional smooths of the locations of the streamgages and the centroids of their basins, indicated that a weighted mean flood skew of -0.132, with a mean squared error of 0.160 and standard error of 0.400, was appropriate. The regional flood skew agrees well with regional flood skew previously developed for Arkansas and Louisiana(skew -0.17, MSE 0.12) using Bayesian generalized least-squares (B-GLS) regression and most of the streamgages in this study (Wagner and others, 2016, appendix 1). The regional flood skew was incorporated in a final flood-frequency analysis in PeakFQ software using a weighted skew (England and others, 2019). In addition to the 71 streamgages used to develop the regional flood skew, five active streamgages that were screened for redundancy (four in Missouri and one in Arkansas) were included in the final flood-frequency analysis. The final estimates of streamflows corresponding to the selected AEPs (0.5, 0.2, 0.1, 0.04, 0.02, 0.01, and 0.002) were weighted with estimates of the same AEPs computed using regional regression equations (Southard and Veilleux, 2014; Wagner and others, 2016) to generate the final weighted estimates, their variances, and 95-percent confidence intervals.

This dataset contains site information, basin characteristics, results of flood-frequency analysis, and a generalized (regional) flood skew for 76 selected streamgages operated by the U.S. Geological Survey (USGS) in the upper White River basin (4-digit hydrologic unit 1101) in southern Missouri and northern Arkansas. The Little Rock District U.S. Army Corps of Engineers (USACE) needed updated estimates of streamflows corresponding to selected annual exceedance probabilities (AEPs) and a basin-specific regional flood skew. USGS selected 111 candidate streamgages in the study area that had 20 or more years of gaged annual peak-flow data available through the 2020 water year. After screening for regulation, urbanization, redundant/nested basins, drainage areas greater than 2,500 square miles, and streamgage basins located in the Mississippi Alluvial Plain (8-digit hydrologic unit 11010013), 77 candidate streamgages remained. After conducting the initial flood-frequency analysis to generate at-site (station) skew and its mean squared error (MSE) for development of the regional flood skew, four streamgages with less than 20 years of pseudo effective record length (PRL) and two streamgages with an excessive amount of censored annual peak flows were removed, leaving 71 streamgages (44 in Arkansas and 27 in Missouri) for use in the study. Flood-frequency analysis was done using the Expected Moments Algorithm (EMA) in version 7.3 of USGS software PeakFQ (Veilleux and others, 2014; England and others, 2019). Ten basin characteristics were tested as explanatory variables in a generalized additive model (GAM) of flood skew, but a lack of statistical significance of the variables, including two-dimensional smooths of the locations of the streamgages and the centroids of their basins, indicated that a weighted mean flood skew of -0.132, with a mean squared error of 0.160 and standard error of 0.400, was appropriate. The regional flood skew agrees well with regional flood skew previously developed for Arkansas and Louisiana(skew -0.17, MSE 0.12) using Bayesian generalized least-squares (B-GLS) regression and most of the streamgages in this study (Wagner and others, 2016, appendix 1). The regional flood skew was incorporated in a final flood-frequency analysis in PeakFQ software using a weighted skew (England and others, 2019). In addition to the 71 streamgages used to develop the regional flood skew, five active streamgages that were screened for redundancy (four in Missouri and one in Arkansas) were included in the final flood-frequency analysis. The final estimates of streamflows corresponding to the selected AEPs (0.5, 0.2, 0.1, 0.04, 0.02, 0.01, and 0.002) were weighted with estimates of the same AEPs computed using regional regression equations (Southard and Veilleux, 2014; Wagner and others, 2016) to generate the final weighted estimates, their variances, and 95-percent confidence intervals.

This dataset contains site information and results of flood-frequency analysis for 139 urban streamflow gaging stations (streamgages) operated by the U.S. Geological Survey (USGS) in Tennessee and parts of Alabama, Georgia, Mississippi, North Carolina, and South Carolina. Developed imperviousness in the basins, based on the 2011 National Land Cover Database, was at least 10 percent (Homer and others, 2015). Drainage areas of the streamgage basins ranged from 0.15 - 161 square miles. Annual peak-flow data from the 1947 - 2022 water years were used in the study (U.S. Geological Survey, 2024). Peak-flow (.pkf), specification (.psf), output (.PRT), and export (.EXP) files from flood-frequency analysis in USGS PeakFQ software (Veilleux and others, 2014; Flynn and others, 2006) are provided. Site information and results of flood-frequency analysis are provided in .csv format.

This dataset contains site information and results of flood-frequency analysis for 139 urban streamflow gaging stations (streamgages) operated by the U.S. Geological Survey (USGS) in Tennessee and parts of Alabama, Georgia, Mississippi, North Carolina, and South Carolina. Developed imperviousness in the basins, based on the 2011 National Land Cover Database, was at least 10 percent (Homer and others, 2015). Drainage areas of the streamgage basins ranged from 0.15 - 161 square miles. Annual peak-flow data from the 1947 - 2022 water years were used in the study (U.S. Geological Survey, 2024). Peak-flow (.pkf), specification (.psf), output (.PRT), and export (.EXP) files from flood-frequency analysis in USGS PeakFQ software (Veilleux and others, 2014; Flynn and others, 2006) are provided. Site information and results of flood-frequency analysis are provided in .csv format.

The U.S. Geological Survey (USGS), in cooperation with the New Mexico Department of Transportation, estimated the magnitude and frequency of floods corresponding to the 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities (AEPs; otherwise known as the 2-, 5-, 10-, 25-, 50-, 100-, 200-, and 500-year floods, respectively) for 346 selected streamgages in New Mexico and parts of Arizona, Colorado, Oklahoma, Texas, and Utah using data through water year 2020. An updated regional flood skew, -0.145, standard error 0.454, was computed for the study area. Regression equations were developed which can be used to estimate the magnitude and frequency of floods at ungaged locations on unregulated streams in the study area. The methods and results of the study are published in the parent report (Bell and others, 2022, https://doi.org/10.5066/XXXXXXXX). For the 346 selected streamgages, this dataset includes peak-flow (*.pkf) and specification (*.psf), output (*.PRT), and export (*.EXP) files from version 7.3 of USGS PeakFQ software (Veilleux and others, 2014; Flynn and others, 2006). Within PeakFQ software, the Expected Moments Algorithm (EMA) was used to conduct frequency analyses to estimate stream discharges corresponding to the 0.5, 0.2, 0.1, 0.04, 0.02, 0.01, 0.005, and 0.002 AEPs. When appropriate, the updated regional skew was used to weight the at-site skew in the frequency analyses. Results of the frequency analyses were used in generalized least-squares (GLS) regression to generate equations that predict discharges corresponding to selected AEPs at ungaged locations on streams in the study area (Bell and others, 2022).

This data release provides the source data and results of a flood frequency analysis and annual exceedance probability estimation for a flood that occurred on July 11, 2022 in the Delta River Basin, Alaska. Data are provided for two streamgages that had at least 10 years of peak-flow record. The data include streamgage information, PeakFQ input (.txt and .PSF files) PeakFQ output (.PRT, .EXP, and .JPEG files), flood frequency parameters, flood frequency estimates for the 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities, and annual exceedance probability estimates for the flood of interest. These data were intended to support investigations of streamflow in the Delta River Basin.

This data release provides the source data and results of a flood frequency analysis and annual exceedance probability estimation for a flood that occurred on July 11, 2022 in the Delta River Basin, Alaska. Data are provided for two streamgages that had at least 10 years of peak-flow record. The data include streamgage information, PeakFQ input (.txt and .PSF files) PeakFQ output (.PRT, .EXP, and .JPEG files), flood frequency parameters, flood frequency estimates for the 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities, and annual exceedance probability estimates for the flood of interest. These data were intended to support investigations of streamflow in the Delta River Basin.

This file contains results of peak-flow frequency analyses for selected streamgages in Montana, North Dakota, South Dakota, and Wyoming, along with information documenting the input data and specifications for the analyses. The analyses were performed using the methods described by Siefken and others (2025).