This data release contains the results from a comprehensive field study that applied paleoflood hydrology methods to estimate the frequency of low-probability floods for the Tennessee River near Chattanooga, Tennessee. The study combined stratigraphic records of large, previously unrecorded floods with modern systematic flood records and historical flood accounts.

To improve estimates of the frequency of annual peak flows for ungaged locations on non-urban, unregulated streams in Tennessee, generalized least-squares (GLS) multiple linear-regression techniques were used to relate annual peak flows from streamflow gaging stations (streamgages) operated by the U.S. Geological Survey (USGS) to physical, climatic, and land-use characteristics of their drainage basins. Geospatial data acquired since the previous study in 2003, annual peak-streamflow data through the 2013 water year, and Bulletin 17C (England and others, 2018) methods for frequency analysis of annual peak-streamflow data were used in the study. GLS regression equations were developed for four hydrologic areas with distinct hydrologic, geologic, and topographic characteristics. These regression equations can be used to estimate annual exceedance probability streamflows for ungaged locations on non-urban, unregulated streams in Tennessee. The term “unregulated” is an adjective indicating that streamflow is not appreciably influenced by regulation from reservoirs or other impoundments. This data release contains the tabular (eight .csv files) and geospatial data used in the associated report by Ladd and Ensminger (2025), including a raster file representing percentage of impervious area, a shapefile of hydrologic areas used for regression regionalization, and shapefiles containing basin boundaries and outlet locations for streamgages used in the associated regression analysis. Tables A, B, and 1 through 6, referenced in the accompanying report (Ladd and Ensminger, 2025), are included as part of this data release. Information specific to those tables, such as attribute information, is described in this metadata document. Reference: England, J.F., Jr., Cohn, T.A., Faber, B.A., Stedinger, J.R., Thomas, W.O., Jr., Veilleux, A.G., Kiang, J.E., and Mason, R.R., Jr., 2018, Guidelines for determining flood flow frequency—Bulletin 17C (ver. 1.1, May 2019): U.S. Geological Survey Techniques and Methods, book 4, chap. B5, 148 p., https://doi.org/10.3133/tm4B5. Ladd, D.E. and Ensminger, P.A., 2025, Estimating the magnitude and frequency of floods at ungaged locations on streams in Tennessee through the 2013 water year: U.S. Geological Survey Scientific Investigations Report 2024-5130, 19 p., https://doi.org/10.3133/sir20245130.

To improve estimates of the frequency of annual peak flows for ungaged locations on non-urban, unregulated streams in Tennessee, generalized least-squares (GLS) multiple linear-regression techniques were used to relate annual peak flows from streamflow gaging stations (streamgages) operated by the U.S. Geological Survey (USGS) to physical, climatic, and land-use characteristics of their drainage basins. Geospatial data acquired since the previous study in 2003, annual peak-streamflow data through the 2013 water year, and Bulletin 17C (England and others, 2018) methods for frequency analysis of annual peak-streamflow data were used in the study. GLS regression equations were developed for four hydrologic areas with distinct hydrologic, geologic, and topographic characteristics. These regression equations can be used to estimate annual exceedance probability streamflows for ungaged locations on non-urban, unregulated streams in Tennessee. The term “unregulated” is an adjective indicating that streamflow is not appreciably influenced by regulation from reservoirs or other impoundments. This data release contains the tabular (eight .csv files) and geospatial data used in the associated report by Ladd and Ensminger (2025), including a raster file representing percentage of impervious area, a shapefile of hydrologic areas used for regression regionalization, and shapefiles containing basin boundaries and outlet locations for streamgages used in the associated regression analysis. Reference: England, J.F., Jr., Cohn, T.A., Faber, B.A., Stedinger, J.R., Thomas, W.O., Jr., Veilleux, A.G., Kiang, J.E., and Mason, R.R., Jr., 2018, Guidelines for determining flood flow frequency—Bulletin 17C (ver. 1.1, May 2019): U.S. Geological Survey Techniques and Methods, book 4, chap. B5, 148 p., https://doi.org/10.3133/tm4B5. Ladd, D.E. and Ensminger, P.A., 2025, Estimating the magnitude and frequency of floods at ungaged locations on streams in Tennessee through the 2013 water year: U.S. Geological Survey Scientific Investigations Report 2024-5130, 19 p., https://doi.org/10.3133/sir20245130.

Digital flood-inundation maps were created by the U.S. Geological Survey (USGS) in cooperation with the Muskingum Watershed Conservancy District and the City of Rittman as part of a Federal Emergency Management Agency (FEMA) Flood Insurance Study (FIS). The flood-inundation maps show estimates of the areal extent corresponding to the 1% and 0.2% annual-exceedance probability floods. Flood profiles were computed for each stream reach by means of a one-dimensional step-backwater model.

Digital flood-inundation maps were created by the U.S. Geological Survey (USGS) in cooperation with the Muskingum Watershed Conservancy District and the City of Rittman as part of a Federal Emergency Management Agency (FEMA) Flood Insurance Study (FIS). The flood-inundation maps show estimates of the areal extent corresponding to the 1% and 0.2% annual-exceedance probability floods. Flood profiles were computed for each stream reach by means of a one-dimensional step-backwater model.

Water-surface elevations along the stream reach were estimated by steady-state hydraulic modeling, assuming unobstructed flow, and using streamflows and hydrologic conditions anticipated at the USGS streamgage (station number 04206425). The hydraulic model reflects the land-cover characteristics and any bridge, dam, levee, or other hydraulic structures existing as of September 2023. _README_Contents-Directory.txt 1. model-software-version.txt (file) Identifies the modeling software, version, and website. 2. modelgeoref.txt (file) Includes reference to the model documentation report, data release, and bounding box coordinates. 3. Source (directory) Contains the URL to the installer files. 4. Model (directory) Contains the model input and output files for the hydraulic model.

Water-surface elevations along the stream reach were estimated by steady-state hydraulic modeling, assuming unobstructed flow, and using streamflows and hydrologic conditions anticipated at the USGS streamgage (station number 04206425). The hydraulic model reflects the land-cover characteristics and any bridge, dam, levee, or other hydraulic structures existing as of September 2023. _README_Contents-Directory.txt 1. model-software-version.txt (file) Identifies the modeling software, version, and website. 2. modelgeoref.txt (file) Includes reference to the model documentation report, data release, and bounding box coordinates. 3. Source (directory) Contains the URL to the installer files. 4. Model (directory) Contains the model input and output files for the hydraulic model.

To improve estimates of the frequency of annual peak flows for ungaged locations on non-urban, unregulated streams in Tennessee, generalized least-squares (GLS) multiple linear-regression techniques were used to relate annual peak flows from streamflow gaging stations (streamgages) operated by the U.S. Geological Survey (USGS) to physical, climatic, and land-use characteristics of their drainage basins. Geospatial data acquired since the previous study in 2003, annual peak-streamflow data through the 2013 water year, and Bulletin 17C (England and others, 2018) methods for frequency analysis of annual peak-streamflow data were used in the study. GLS regression equations were developed for four hydrologic areas with distinct hydrologic, geologic, and topographic characteristics. These regression equations can be used to estimate annual exceedance probability streamflows for ungaged locations on non-urban, unregulated streams in Tennessee. The term “unregulated” is an adjective indicating that streamflow is not appreciably influenced by regulation from reservoirs or other impoundments. This data release contains the tabular (eight .csv files) and geospatial data used in the associated report by Ladd and Ensminger (2025), including a raster file representing percentage of impervious area, a shapefile of hydrologic areas used for regression regionalization, and shapefiles containing basin boundaries and outlet locations for streamgages used in the associated regression analysis. The geospatial datasets and accompanying metadata can be found in the three zip folders called "hydrologic_areas," "impervious_area," and "streamgages." Reference: England, J.F., Jr., Cohn, T.A., Faber, B.A., Stedinger, J.R., Thomas, W.O., Jr., Veilleux, A.G., Kiang, J.E., and Mason, R.R., Jr., 2018, Guidelines for determining flood flow frequency—Bulletin 17C (ver. 1.1, May 2019): U.S. Geological Survey Techniques and Methods, book 4, chap. B5, 148 p., https://doi.org/10.3133/tm4B5. Ladd, D.E. and Ensminger, P.A., 2025, Estimating the magnitude and frequency of floods at ungaged locations on streams in Tennessee through the 2013 water year: U.S. Geological Survey Scientific Investigations Report 2024-5130, 19 p., https://doi.org/10.3133/sir20245130.

This file contains results of peak-flow frequency analyses for selected streamgages in and near Lincoln County, Montana, 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).

Reliable estimates of the magnitude and frequency of floods are an important part of the framework for hydraulic-structure design and flood-plain management in Georgia, South Carolina, and North Carolina (study area). Annual peak flows measured at U.S. Geological Survey streamgages were used to compute at-site flood-frequency estimates at those streamgages in the study area based on annual peak-flows records through 2017. Flood-frequency estimates also are needed at ungaged stream locations. A process known as regionalization was used to develop regression equations to estimate the magnitude and frequency of floods at ungaged locations. This model archive provides the inputs and outputs for (1) the at-site flood-frequency statistics and (2) the regression models developed to allow for estimation of flood-frequency statistics at ungaged stream locations in the study area. The inputs and outputs for the at-site flood-frequency statistics are provided under the SAWSC PeakFQ input and output files for at-site flood-frequency statistics child item. The inputs and outputs for the regression models are provided under the SAWSC rural flood-frequency regression models (R scripts and applications) child item. Further details concerning the inputs and outputs are provided within the metadata and ReadMe files underneath each child item within this data release. Information describing the contents of this model archive is provided below in a text-based file attached to the front landing page for this data release.