OHIO RIVER BACKWATER FLOOD-INUNDATION MAPS FOR THE SALINE AND WABASH RIVERS IN SOUTHERN ILLINOIS By Elizabeth A. Murphy, Jennifer B. Sharpe, and David T. Soong 2012 U.S. Geological Survey Scientific Investigations Report 5212 ABSTRACT: Digital flood-inundation maps for the Saline and Wabash Rivers referenced to elevations on the Ohio River in southern Illinois were created by the U.S. Geological Survey (USGS). The inundation maps, accessible through the USGS Flood Inundation Mapping Science Web site at http://water.usgs.gov/osw/flood_inundation/, depict estimates of the areal extent of flooding corresponding to selected water levels (gage heights) at the USGS streamgage at Ohio River at Old Shawneetown, Illinois-Kentucky (station number 03381700). Current gage height and flow conditions at this USGS streamgage may be obtained on the Internet at http://waterdata.usgs.gov/usa/nwis/uv?03381700. In addition, this streamgage is incorporated into the Advanced Hydrologic Prediction Service (AHPS) flood warning system (http://water.weather.gov/ahps/) by the National Weather Service (NWS). The NWS forecasts flood hydrographs at many places that are often co-located at USGS streamgages. That NWS forecasted peak-stage information, also shown on the Ohio River at Old Shawneetown inundation Web site, may be used in conjunction with the maps developed in this study to show predicted areas of flood inundation. In this study, eight water-surface elevations were mapped at 5-foot (ft) intervals referenced to the streamgage datum ranging from just above the NWS Action Stage (31 ft) to above the maximum historical gage height (66 ft). The elevations of the water surfaces were compared to a Digital Elevation Model (DEM) by using a Geographic Information System (GIS) in order to delineate the area flooded at each water level. These maps, along with information on the Internet regarding current gage heights from USGS streamgages and forecasted stream stages from the NWS, 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. Revision: Eighteen water-surface elevations were mapped at 2-foot intervals referenced to the streamgage datum ranging from just above the Action Stage (31 ft) to approximately the the maximum historical gage height (65 ft). The elevations of the water surfaces were compared to a Digital Elevation Model (DEM) created with Light Detection and Ranging data by using a Geographic Information System in order to delineate the area flooded at each level. DISCLAIMERS: 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. 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. This data base, identified as SIR 5212, 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. Inundated areas shown should not be used for navigation, regulatory, permitting, or other legal purposes. The USGS 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. 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 gage heights (water-surface elevations) at a selected USGS streamgage. Water-surface elevations along the stream reaches were estimated by assuming unobstructed flow and using hydrologic conditions anticipated at the USGS streamgage. Unique meteorological factors (timing and distribution of precipitation) may cause actual water-surface elevations along the mapped reach to vary from those assumed during a flood, which may lead to deviations in the inundation boundaries shown. Additional areas may be flooded due to unanticipated conditions such as changes in the streambed elevation or roughness, 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. 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. As mentioned previously, a USGS Flood Inundation Mapping Science World Wide Web portal has been established at URL http://water.usgs.gov/osw/flood_inundation/ to provide estimated flood-inundation information to the public. Although USGS intends to make this server available 24 hours a day, 7 days a week, timely delivery of data and products from this server through the Internet is not guaranteed. CONTENTS: 00Readme.txt SIR5212.pdf SIR5212_metadata.met SIR5212_map_sheets.zip (sheets 1 through 8 in .pdf format) SIR5212_newSeptember2014.met datafiles: This report consists of a report with 8 map sheets, each sheet has data files, and the single metadata file pertains to all of the maps. The revision consists of one shapefile with 18 inundation surfaces and a metadata file for the revision shapefile. SIR5212_Shapefiles.zip The shapefiles are as follows: 03381700_31.shp (.dbf/.prj/.sbn/.sbx/.shx) 03381700_36.shp (.dbf/.prj/.sbn/.sbx/.shx) 03381700_41.shp (.dbf/.prj/.sbn/.sbx/.shx) 03381700_46.shp (.dbf/.prj/.sbn/.sbx/.shx) 03381700_51.shp (.dbf/.prj/.sbn/.sbx/.shx) 03381700_56.shp (.dbf/.prj/.sbn/.sbx/.shx) 03381700_61.shp (.dbf/.prj/.sbn/.sbx/.shx) 03381700_66.shp (.dbf/.prj/.sbn/.sbx/.shx) Saline_IL.shp (.dbf/.prj/.sbn/.sbx/.shx) SIR5212_kmz (folder) SIR5212_kmz.zip Saline_lidar_revision.kmz VI. INSTRUCTIONS AND DOCUMENTATION FOR U.S. GEOLOGICAL SURVEY SCIENTIFIC INVESTIGATIONS REPORT 5212 To access the data: The data files can be downloaded via the web from http://pubs.usgs.gov/sir/5212. The main product is a Portable Document Format (.pdf) report 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. To access the .kmz files in this report, download and install Google Earth free of charge at http://www.google.com/earth/index.htm. Launch Google Earth, click the file menu and choose open. Locate and select the .kmz file on your computer. References to non-U.S. Department of the Interior (DOI) products do not constitute an endorsement by the DOI. By viewing the Google Maps API on this web site the user agrees to these terms(terms found at: http://code.google.com/apis/maps/terms.html) of Service set forth by Google. Software Recommended: 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.