FLOOD-INUNDATION MAPS FOR THE FLATROCK RIVER AT COLUMBUS, INDIANA, 2012 By William F. Coon 2013 U.S. Geological Survey Scientific Investigations Map 3241 ABSTRACT: Digital flood-inundation maps for a 5-mile reach of the Flatrock River on the western side of Columbus, Indiana, from County Road 400N to the river mouth at the confluence with Driftwood River, were created by the U.S. Geological Survey (USGS) in cooperation with the Indiana Department of Transportation. The inundation maps, which can be accessed through the USGS Flood Inundation Mapping Science Web site at http://water.usgs.gov/osw/flood_inundation/ and the Federal Flood Inundation Mapper Web site at http://wim.usgs.gov/FIMI/FloodInundationMapper.html, depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at the USGS streamgage on the Flatrock River at Columbus (station number 03363900). Near-real-time stages at this streamgage may be obtained on the Internet from the USGS National Water Information System at http://waterdata.usgs.gov/ or the National Weather Service (NWS) Advanced Hydrologic Prediction Service, which also presents the USGS data, at http:/water.weather.gov/ahps/. Flood profiles were computed for the stream reach by means of a one-dimensional step-backwater model. The model was calibrated by using the most current stage-discharge relation at the Flatrock River streamgage, high-water marks that were surveyed following the flood of June 7, 2008, and water-surface profiles from the current flood-insurance study for the City of Columbus. The hydraulic model was then used to compute 12 water-surface profiles for flood stages at 1-foot (ft) intervals referenced to the streamgage datum and ranging from 9 ft or near bankfull to 20 ft, which exceeds the stages that correspond to both the estimated 0.2-percent annual exceedance probability flood (500-year recurrence interval flood) and the maximum recorded peak flow. The simulated water-surface profiles were then combined with a Geographic Information System digital elevation model (derived from Light Detection and Ranging (LiDAR) data having a 0.37ft vertical accuracy and 3.9ft horizontal resolution) to delineate the area flooded at each water level. The availability of these maps on the USGS Federal Flood Inundation Mapper Web site, along with Internet information regarding current stage from the USGS streamgage, will provide emergency management personnel and residents with information that is critical for flood response activities, such as evacuations and road closures, as well as for post-flood recovery efforts. DISCLAIMERS: This data base, identified as SIM 3241, has been approved for release and publication by the Director of the U.S. Geological Survey. Although this database has been subjected to rigorous review and is substantially complete, the U.S. Geological Survey reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the U.S. Geological Survey nor the U.S. Government may be held liable for any damages resulting from its authorized or unauthorized use. Although these data have been processed successfully on a computer system at the U.S. Geological Survey, 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. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and/or contained herein. Any use of trade, product, or firm 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 also contains copyrighted materials as noted in the text. Permission to reproduce copyrighted items for other than personal use must be secured from the copyright owner. Disclaimer for Flood-Inundation Maps: Inundated areas shown on the flood maps should not be used for navigation, regulatory, permitting, or other legal purposes. The USGS provides these maps “asis” for a quick reference, emergency planning tool but assumes no legal liability or responsibility resulting from the use of this information. Uncertainties and Limitations for Use of Flood-Inundation Maps: Although the flood-inundation maps represent the boundaries of inundated areas with a distinct line, some uncertainty is associated with these maps. The flood boundaries shown were estimated on the basis of water stages at the USGS streamgage on the Flatrock River at Columbus (03363900). Water-surface elevations along the stream reaches were estimated by steady-state hydraulic modeling, assuming unobstructed flow, and using streamflows and hydrologic conditions anticipated at the USGS streamgage. The hydraulic model reflects the land-cover characteristics and any bridge, dam, levee, or other hydraulic structures existing as of March 2012. Unique meteorological factors (timing and distribution of precipitation) may cause actual streamflows along the modeled reach to vary from those assumed during a flood, which may lead to deviations in the water-surface elevations and inundation boundaries shown. Additional areas may be flooded due to unanticipated conditions, such as changes in the streambed elevation or roughness, backwater into major tributaries along a main-stem river, or backwater from localized debris or ice jams. The accuracy of the floodwater extent portrayed on these maps will vary with the accuracy of the digital elevation model used to simulate the land surface. Additional uncertainties and limitations pertinent to this study may be described elsewhere in this report. If this series of flood-inundation maps will be used in conjunction with National Weather Service (NWS) river forecasts, the user should be aware of additional uncertainties that may be inherent or factored into NWS forecast procedures. The NWS uses forecast models to estimate the quantity and timing of water flowing through selected stream reaches in the United States. These forecast models (1) estimate the amount of runoff generated by precipitation and snowmelt, (2) simulate the movement of floodwater as it proceeds downstream, and (3) predict the flow and stage (water-surface elevation) for the stream at a given location (AHPS forecast point) throughout the forecast period (every 6 hours and 3 to 5 days out in many locations). For more information on AHPS forecasts, please see http://water.weather.gov/ahps/pcpn_and_river_forecasting.pdf. CONTENTS: This report consists of a pamphlet and 12 map sheets. The individual polygon shapefiles and depth grids as described below are available for download, as are the associated metadata files. 00Readme.txt SIM3241_pamphlet.pdf metadata_shapefiles_sp.xml metadata_grids_sp.xml DATAFILES The 12 shapefiles are included in the file, shapefile.zip as follows: elev_618_7.shp (.dbf/.prj/.sbn/.sbx/.shp.xml/.shx) elev_619_7.shp (.dbf/.prj/.sbn/.sbx/.shp.xml/.shx) elev_620_7.shp (.dbf/.prj/.sbn/.sbx/.shp.xml/.shx) elev_621_7.shp (.dbf/.prj/.sbn/.sbx/.shp.xml/.shx) elev_622_7.shp (.dbf/.prj/.sbn/.sbx/.shp.xml/.shx) elev_623_7.shp (.dbf/.prj/.sbn/.sbx/.shp.xml/.shx) elev_624_7.shp (.dbf/.prj/.sbn/.sbx/.shp.xml/.shx) elev_625_7.shp (.dbf/.prj/.sbn/.sbx/.shp.xml/.shx) elev_626_7.shp (.dbf/.prj/.sbn/.sbx/.shp.xml/.shx) elev_627_7.shp (.dbf/.prj/.sbn/.sbx/.shp.xml/.shx) elev_628_7.shp (.dbf/.prj/.sbn/.sbx/.shp.xml/.shx) elev_629_7.shp (.dbf/.prj/.sbn/.sbx/.shp.xml/.shx) The 12 depth grids are included in the file, depth_grids.zip as follows: elev_618_7 elev_619_7 elev_620_7 elev_621_7 elev_622_7 elev_623_7 elev_624_7 elev_625_7 elev_626_7 elev_627_7 elev_628_7 elev_629_7 The 12 map sheets are included in the file, map_sheets.zip (in .pdf format)as follows: sheet1_618_74ft.pdf sheet2_619_74ft.pdf sheet3_620_74ft.pdf sheet4_621_74ft.pdf sheet5_622_74ft.pdf sheet6_623_74ft.pdf sheet7_624_74ft.pdf sheet8_625_74ft.pdf sheet9_626_74ft.pdf sheet10_627_74ft.pdf sheet11_628_74ft.pdf sheet12_629_74ft.pdf The map sheets are also available individually under the subdirectory: /map_sheets INSTRUCTIONS AND DOCUMENTATION FOR U.S. GEOLOGICAL SURVEY SCIENTIFIC INVESTIGATIONS MAP 3231 To access the data: The data files can be downloaded via the web from http://pubs.usgs.gov/sim/3241.The main product is a Portable Document Format (.pdf) map and pamphlet which requires Adobe Acrobat for viewing. Acrobat software runs on a variety of systems, and is available for download free of charge from Adobe at http://www.adobe.com. References to non-U.S. Department of the Interior (DOI) products do not constitute an endorsement by the DOI. Software preferred: Adobe Acrobat (6.x, 7.x, or 8.x), or Adobe Acrobat Pro (6.x, 7.x, or 8.x), or the free Adobe Reader (6.x, 7.x, or 8.x), 8.x is preferred. ArcGIS 10.0 preferred, older versions may also work. ArcReader may be downloaded free of charge from http://www.esri.com/software/arcgis/arcreader/download.htm for viewing additional files included in this report.