Weaver, J. Curtis Feaster, Toby D. Gotvald, Anthony J. Musser, Jonathan W. Kolb, Katharine R. 20230428 Text files Reston, VA U.S. Geological Survey https://doi.org/10.5066/P9AQ2AX1 Feaster, Toby D. Gotvald, Anthony J. Musser, Jonathan W. Weaver, J. Curtis Kolb, Katharine R. 20230501 publication Reston, VA U.S. Geological Survey https://doi.org/10.3133/sir20235006 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). 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 in the study area. The previous update to rural flood frequency estimates in the study area was published using annual peak-flow data through 2006. This updated study utilizes newer methods outlined in Bulletin 17C and newly developed regional skew to estimate the magnitude and frequency of floods in the study area based on data through 2017. The USGS data under this child item provides input and output files used to complete at-site flood-frequency statistics developed as a part of this study. Input files (of annual peak-flow records) and PeakFQ specification files specific to the streamgages considered in this study are provided along with the output files generated from the use of the PeakFQ version 7.4 software (release date June 28, 2022). 1771 20170930 Period of record analyzed Complete None planned -85.9026 -75.2404 37.5369 29.9450 ISO 19115 Topic Category inlandWaters climatologyMeteorologyAtmosphere geoscientificInformation USGS Thesaurus floods streamflow geospatial datasets hydrology geography natural resources surface water hazard preparedness discharge Other Keywords streamgage flood frequency basin PeakFQ software Weighted-Multiple-Linear Regression (WREG) Program USGS Metadata Identifier USGS:61ba43e9d34e9e224ac12ef8 Geographic Names Information System (GNIS) Alabama Florida Georgia North Carolina South Carolina Tennessee Virginia United States USGS Thesaurus Holocene Era None. Please see 'Distribution Info' for details. Although these data have been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of this data, software, or related materials. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. This dataset may be redistributed if it is not edited and is properly referenced. Although USGS intends to make this server available 24 hours a day, seven days a week, timely delivery of data and products from this server through the Internet is not guaranteed. John C Weaver U.S. Geological Survey, SOUTHEAST REGION Hydrologist mailing address

3916 Sunset Ridge Rd

Raleigh NC 27607 US 919-571-4043 919-571-4041 jcweaver@usgs.gov Georgia Department of Transportation, South Carolina Department of Transportation (Hydraulic Design Support Office), North Carolina Department of Transportation (Division of Highways - Hydraulics Unit), and the North Carolina Department of Crime Control and Public Safety (Division of Emergency Management - Floodplain Mapping Program) Kolb, Katharine R. Musser, Jonathan W. Feaster, Toby D. Gotvald, Anthony J. Weaver, J. Curtis 20230501 tabular and geospatial data Reston, VA U.S. Geological Survey https://doi.org/10.5066/P9TSBPFS No formal attribute accuracy tests were conducted. Peak data are reviewed by the U.S. Geological Survey as part of standard quality assurance procedures. Some input parameters such as perception thresholds (part of the PeakFQ inputs for the analyses of at-site flood-frequency statistics) are based on the judgement of the analyst. Data set is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details. No formal positional accuracy tests were conducted. No formal positional accuracy tests were conducted. Peak-flow files were downloaded in WATSTORE format from the U.S. Geological Survey National Water Information System database (https://waterdata.usgs.gov/usa/nwis/nwis) for the relevant streamflow gaging stations for the three-state study area (Georgia, South Carolina, and North Carolina) and four adjacent states (Florida, Alabama, Tennessee, and Virginia). The peak-flow files were loaded into the U.S. Geological Survey PeakFQ version 7.4 (release date June 28, 2022) software, and appropriate perception thresholds and flow intervals were used as deemed appropriate and applicable. PeakFQ version 7.4 produced the magnitude flood flows at specified frequency intervals, as well as output files (.prt, .exp and .tab, which are text-based format). The .prt and .exp output files are used as part of the input files in the USGS Weighted-multiple-linear REGression (WREG) software (please see the "SAWSC rural flood-frequency regression models (R scripts and applications)" child item in this data release). Detailed information on the input and output files used for the PeakFQ analyses completed are provided in the primary USGS publication (Feaster and others, 2023) associated with this model archive. PeakFQ version 7.4 is available for download from the USGS at https://water.usgs.gov/software/PeakFQ/. Within this data release, the input and output files as well as a copy of the PeakFQ version 7.4 software are provided via the "SAWSC PeakFQ input and output files for at-site flood-frequency statistics" child item. The periods of record used in the PeakFQ analyses are based on systematic discharge records through the 2017 water year for the unregulated streamgages. As the primary focus of the study was on the at-site flood-frequency statistics for unregulated streamgages used in the development of the regression models, the End Date specified on the front landing page for this data release is listed as 2017-09-30. The Start Date of 1771 is associated with a historical peak qualification referenced for the 1940 water year peak flow at USGS Sta. 02080500 Roanoke River at Roanoke Rapids, NC. This historial reference was used in one of the perception thresholds specified in the PeakFQ analysis completed for this streamgage. For the regulated streamgages, the periods of records through the 2019 water year were used for the PeakFQ analyses. 2022 8.9831528411952133e-09 8.9831528411952133e-09 Decimal degrees North_American_Datum_1983 GRS_1980 6378137.0 298.257222101 ReadMe_USGS_PeakFQ_procedures_textonly.txt Text-based (.txt) version of ReadMe file that provides a brief description of the general procedures needed to open and run the USGS PeakFQ software for a specific PeakFQ specification file (.psf) to generate output containing at-site flood-frequency statistics. Producer Defined ReadMe_USGS_PeakFQ_procedures_illustrated.pdf Adobe Acobat (.pdf) version of ReadMe file that provides a brief description (with screen shots) of the general procedures needed to open and run the USGS PeakFQ software for a specific PeakFQ specification file (.psf) to generate output containing at-site flood-frequency statistics. Producer Defined SAWSC_PeakFQ_inputs_unregulated.zip Zip file containing PeakFQ specification file (.psf) and annual peak-flow records (.txt) for the 965 unregulated streamgages. Units for discharges in the annual peak-flow records are cubic feet per second (cfs). Note: Due to a memory issue with the PeakFQ version 7.4 software, the at-site flood-frequency analyses could not be completed for all 965 sites in one session. The input files had to be subdivided into 8 smaller groups of sites for analyses which also resulted in 8 groups of output files. This inputs zip file contains the following 8 sub-folders (with indicated numbers of sites) for the unregulated sites: SAWSC_UNREG1 (106 sites), SAWSC_UNREG2 (128 sites), SAWSC_UNREG3 (135 sites), SAWSC_UNREG4 (131 sites), SAWSC_UNREG5 (144 sites), SAWSC_UNREG6 (128 sites), SAWSC_UNREG7 (106 sites), and SAWSC_UNREG8 (87 sites). Producer Defined SAWSC_PeakFQ_outputs_unregulated.zip Zip file containing text-based PeakFQ output files (.prt, .exp, and .tab) for the 965 unregulated streamgages along with .JPEG image files showing flood-frequency Log-Pearson Type III probability curves for each unregulated streamgage. For each of the frequency graphs, the annual peak discharges are plotted along with the fitted frequency curve and confidence limits for the frequency curve. The X-axis shows the annual exceedance probability (in percent), and the Y-axis shows the annual peak discharge (in cubic feet per second). In all graphs and text-based outputs, the units for discharges are cubic feet per second (cfs). Note: Due to a memory issue with the PeakFQ version 7.4 software, the at-site flood-frequency analyses could not be completed for all 965 sites in one session. The input files had to be subdivided into 8 smaller groups of sites for analyses which also resulted in 8 groups of output files. This outputs zip file contains the following 8 sub-folders (with indicated numbers of sites) for the unregulated sites: SAWSC_UNREG1 (106 sites), SAWSC_UNREG2 (128 sites), SAWSC_UNREG3 (135 sites), SAWSC_UNREG4 (131 sites), SAWSC_UNREG5 (144 sites), SAWSC_UNREG6 (128 sites), SAWSC_UNREG7 (106 sites), and SAWSC_UNREG8 (87 sites). Producer Defined SAWSC_PeakFQ_inputs_regulated.zip Zip file containing PeakFQ specification file (.psf) and annual peak-flow records (.txt) for the 72 regulated streamgages. Units for discharges in the annual peak-flow records are cubic feet per second (cfs). Producer Defined SAWSC_PeakFQ_outputs_regulated.zip Zip file containing text-based PeakFQ output files (.prt, .exp, and .tab) for the 72 regulated streamgages along with .JPEG image files showing flood-frequency Log-Pearson Type III probability curves for each regulated streamgage. For each of the frequency graphs, the annual peak discharges are plotted along with the fitted frequency curve and confidence limits for the frequency curve. The X-axis shows the annual exceedance probability (in percent), and the Y-axis shows the annual peak discharge (in cubic feet per second). In all graphs and text-based outputs, the units for discharges are cubic feet per second (cfs). Producer Defined USGS_PeakFQ_setup_executable.zip Zip file containing USGS PeakFQ install executable available online from https://water.usgs.gov/software/PeakFQ/. As of July 2022, USGS PeakFQ version 7.4 (release date June 28, 2022) was available for download and install. Final at-site FF statistics were determined using version 7.4 of the USGS PeakFQ software. A ReadMe file "ReadMe_USGS_PeakFQ_procedures..." (illustrated or text only) included within this child item folder provides additional information concerning the installation and use of the USGS PeakFQ software. Producer Defined 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 Georgia, South Carolina, and North Carolina (study area). The PeakFQ input and output files provided within this child item in this data release are described for the associated datasets. The new methodology using Bulletin 17C procedures are described in the U.S. Geological Survey Techniques and Methods book 4, chapter B5 with output examples from PeakFQ (England and others, 2022). A more detailed description of the actual input and output data file formats are described in the PeakFQ user's manual, U.S. Geological Survey Techniques and Methods book 4, chapter B4 (Flynn and others, 2006), which has not been updated to reflect changes to the newest version of PeakFQ utilizing Bulletin 17C guidelines. Weaver, J. Curtis, Feaster, Toby D., Gotvald, Anthony J., Musser, Jonathan W., and Kolb, Katharine R., 2023, Model Archive for Magnitude and Frequency of Floods for Rural Streams in Georgia, South Carolina, and North Carolina, 2017: U.S. Geological Survey, https://doi.org/10.5066/P9AQ2AX1. Feaster, T.D., Gotvald, A.J., Musser, J.W., Weaver, J.C., Kolb, K.R., Veilleux, A.G., and Wagner, D.M., 2023, Magnitude and frequency of floods for rural streams in Georgia, South Carolina, and North Carolina, 2017—Results: U.S. Geological Survey Scientific Investigations Report 2023–5006, 75 p., https://doi.org/10.3133/sir20235006. 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. Flynn, K.M., Kirby, W.H., and Hummel, P.R., 2006, User’s Manual for Program PeakFQ Annual Flood-Frequency Analysis Using Bulletin 17B Guidelines: U.S. Geological Survey, Techniques and Methods Book 4, Chapter B4; 42 pgs. (Also available at https://pubs.usgs.gov/tm/2006/tm4b4/). Veilleux, A.G.; Cohn, T.A.; Flynn, K.M.; Mason, R.R., Jr.; and Hummel, P.R., 2014, Estimating magnitude and frequency of floods using the PeakFQ 7.0 program: U.S. Geological Survey Fact Sheet 2013–3108, 2 p., accessed October 22, 2015, at https://dx.doi.org/10.3133/fs20133108. GS ScienceBase U.S. Geological Survey mailing and physical

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 United States 1-888-275-8747 sciencebase@usgs.gov Unless otherwise stated, all data, metadata, and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. Although the data have been subjected to rigorous review and are substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, the data are released on the condition that neither the USGS nor the U.S. Government may be held liable for any damages resulting from authorized or unauthorized use. Although these data have been processed successfully on a computer system at the USGS, no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. The USGS or the U.S. Government shall not be held liable for improper or incorrect use of the data described and/or contained herein. Users of these data are advised to read all metadata and associated documentation thoroughly to understand appropriate use and data limitations. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it may contain copyrighted materials. Permission to reproduce copyrighted items must be secured from the copyright owner. The USGS PeakFQ version 7.4 software (release date June 28, 2022) has been approved for release by the USGS. Although the software has been subjected to rigorous review, the USGS reserves the right to update the software as needed pursuant to further analysis and review. No warranty, expressed or implied, is made by the USGS or the U.S. Government as to the functionality of the software and related material nor shall the fact of release constitute any such warranty. Furthermore, the software is released on condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from its authorized or unauthorized use. This zip file contains data available in text format. The user must have software capable of uncompressing the zip file and displaying the text document. All data and analyses provided in this model archive were prepared and assembled on a computer that uses the Microsoft Windows operating system. 20230428 John C Weaver U.S. Geological Survey, SOUTHEAST REGION Hydrologist mailing address

3916 Sunset Ridge Rd

Raleigh NC 27607 US 919-571-4043 jcweaver@usgs.gov Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998