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Scientific Investigations Report 2012–5212

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

Thumbnail of and link to report PDF (72.6 MB)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, 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 In addition, this streamgage is incorporated into the Advanced Hydrologic Prediction Service (AHPS) flood warning system ( 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.

First posted December 5, 2012

Revised September 18, 2014

  • Flood-inundation maps
    for the Saline and Wabash Rivers, Illinois, corresponding to USGS streamgage Ohio River at Old Shawneetown, Illinois-Kentucky (station 03381700).

    Each sheet PDF is about 9 MB

    Gage height of 31 ft, Sheet 1

    Gage height of 36 ft, Sheet 2

    Gage height of 41 ft, Sheet 3

    Gage height of 46 ft, Sheet 4

    Gage height of 51 ft, Sheet 5

    Gage height of 56 ft, Sheet 6

    Gage height of 61 ft, Sheet 7

    Gage height of 66 ft, Sheet 8

For additional information contact:
Director, Illinois Water Science Center
1201 W. University Avenue
Suite 100
Urbana, IL 61801
(217) 328-USGS (8747)

Part or all of this report is presented in Portable Document Format (PDF); the latest version of Adobe Reader or similar software is required to view it. Download the latest version of Adobe Reader, free of charge.

Suggested citation:

Murphy, E.A., Sharpe, J.B., and Soong, D.T., 2012, Ohio River backwater flood-inundation maps for the Saline and Wabash Rivers in southern Illinois (ver. 1.1, September 2014): U.S. Geological Survey Scientific Investigations Report 2012–5212, 20 p., available only at




Constructing Water Surfaces

Inundation Mapping



References Cited


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