Jonathan W. Musser 20180130 Digital Data Set https://doi.org/10.5066/F71N809J Digital flood-inundation maps for a 12.6-mile reach of the Withlacoochee River from Skipper Bridge Road to St. Augustine Road, Lowndes County, Georgia, were created by the U.S. Geologicay Survey (USGS) in cooperation with the city of Valdosta and Lowndes County, Georgia. The inundation maps, which can be accessed through the USGS Flood Inundation Mapping Science Web site at http://water.usgs.gov/osw/flood_inundation/, depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at the USGS streamgage Withlacoochee River at Skipper Bridge Road, near Bemiss, Georgia (023177483). Real-time stage information from this streamgage can be obtained at the National Water Information System Web Interface (NWISWeb; https://waterdata.usgs.gov/ga/nwis/rt) and can be used with these maps to estimate near real-time areas of inundation. In addition, the information has been provided to the National Weather Service (NWS) for incorporation into their Advanced Hydrologic Prediction Service (AHPS; http:/water.weather.gov/ahps/) flood warning system (http:/water.weather.gov/ahps/). The NWS forecasts flood hydrographs at many places that are often collocated at USGS streamgages. The forecasted peak-stage information, also available on the Internet, may be used in conjunction with the maps developed in this study to show predicted areas of flood inundation. In this study, flood profiles were computed for the stream reach by means of a one-dimensional step-backwater model. The model was calibrated using the most current stage-discharge relations at the streamgage Withlacoochee River at Skipper Bridge Road, near Bemiss (023177483) and documented high-water marks from recent floods. The hydraulic model was then used to determine 23 water-surface profiles for flood elevations at 1.0-foot intervals referenced to the water surface elevation and ranging from NWS action stage of 131.0 feet (10.7 feet streamgage stage) to 153.0 feet (32.7 feet streamgage stage) which is near the highest recorded water level at the streamgage. The flood-peak inundation area was modeled in a GIS by combining steady-state hydraulic modeling and available lidar digital elevation model (DEM) data. Information about the study, floods, and methods used can be found in the USGS Scientific Investigations Report 2018-5011 online at https://doi.org/10.3133/sir20185011. This dataset was created to support the development of flood-peak inundation maps for the Withlacoochee River in Lowndes County, Georgia. Shapefiles represent the modeled flood inundation extents of a 12.6-mile reach of the Withlacoochee River from Skipper Bridge Road to St. Augustine Road, Lowndes County, Georgia. These flood inundation extents are for 1.0-foot intervals referenced to the water surface elevation and ranging from streamgage (023177483) stage 10.7 feet to 32.7 feet, and will be used on the U.S. Geological Survey Flood Inundation Mapper website. Rasters represent the inundation depths corresponding to each flood extent. 20180130 publication date Complete None planned -83.344554707 -83.264920717 30.949874389 30.845441969 USGS Thesaurus floods river reaches stream discharge geospatial analysis None high-water marks flood-inundation maps flooded area USGS Metadata Identifier USGS:5a048741e4b0dc0b45b5067b Common geographic areas Georgia Valdosta None Lowndes County None. Please see 'Distribution Info' for details. None. Users are advised to read the data set's metadata thoroughly to understand appropriate use and data limitations. U.S. Geological Survey, Southeast Region Jonathan W Musser Hydrologist mailing address

1770 Corporate Drive Suite 500

Norcross GA 30093 United States 678-924-6675 678-924-6710 jwmusser@usgs.gov City of Valdosta Lowndes County Environment as of Metadata Creation: Microsoft Windows 7 Version 6.1 (Build 7601) Service Pack 1; Esri ArcGIS 10.5.1 (Build 7333) Service Pack N/A (Build N/A) No formal attribute accuracy tests were conducted. No formal logical accuracy tests were conducted. 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. A formal accuracy assessment of the horizontal positional information in the data set has not been conducted. A formal accuracy assessment of the vertical positional information in the data set has either not been conducted, or is not applicable. National Oceanic and Atmospheric Administration 2016 Raster Digital Data Set online National Oceanic and Atmospheric Administration ftp://coast.noaa.gov/pub/DigitalCoast/lidar1_z/geoid12b/data/4971/ Digital and/or Hardcopy Resources 2016 publication date Source Input 1 Source information used in support of the development of the data set. Development of the data set by the agency / individuals identified in the 'Originator' element in the Identification Info section of the record. Unknown Vector G-polygon 1 North_American_Vertical_Datum_1988 1.0 Foot_US Explicit elevation coordinate included with horizontal coordinates The entity and attribute information provided here describes the tabular data associated with the data set. Please review the detailed descriptions that are provided (the individual attribute descriptions) for information on the values that appear as fields/table entries of the data set. The entity and attribute information was generated by the individual and/or agency identified as the originator of the data set. Please review the rest of the metadata record for additional details and information. U.S. Geological Survey GS ScienceBase mailing address

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 for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. Inundated areas shown should not be used for navigation, regulatory, permitting, or other legal purposes. The U.S. Geological Survey provides these maps "as-is" for a quick reference, emergency planning tool but assumes no legal liability or responsibility resulting from the use of this information. digital data set https://doi.org/10.5066/F71N809J None. No fees are applicable for obtaining the data set. 20200827 Jonathan W Musser U.S. Geological Survey, Southeast Region Hydrologist mailing address

1770 Corporate Drive Suite 500

Norcross GA 30093 United States 678-924-6675 678-924-6710 jwmusser@usgs.gov FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998