56

New Haven

Ridgway

Omaha

Galatia

Raleigh

Eldorado

Equality Junction

Shawneetown

Old Shawneetown

Muddy

Harrisburg

34

13 13

145

13

34

1

142

1

45

88°35' 88°30' 88°25' 88°20' 88°15' 88°10' 88°5' 88°

37°50'

37°45'

37°40'

37°35'

Eldorado

Raleigh

Galatia

Omaha

Ridgway

Junction

Shawneetown

Old Shawneetown

Equality

Muddy

Harrisburg

KENTUCKY

ILLINOIS

INDIANA

ILLINOIS

KENTUCKY

ILLINOIS

South

03382200

03381700

Fork

Fork

Middle

North

Fork

Saline

River

River

Ohio

River

Wabash

INDIANA

ILLINOIS

Map

area

Orthography from the USDA Farm Service Agency, Aerial Photography Field Office 2012 National Agriculture Imagery Program (NAIP) Natural Color Imagery for Illinois and Kentucky, accessed in 2012 at http://gis.apfo.usda.gov/arcgis/services.

U.S. DEPARTMENT OF THE INTERIOR

U.S. GEOLOGICAL SURVEY

Scientific Investigations Report 2012–5212

Murphy, E.A., Sharpe, J.B., Soong, D.T., 2012

DISCLAIMER

lnundated 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.

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 based on 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 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 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 are 

described in the document accompanying this set of flood-inundation map sheets.

If this series of flood-inundation maps will be used 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 five days out in many locations). For more information on AHPS forecasts, 

please see: http://water.weather.gov/ahps/pcpn_and_river_forecasting.pdf.

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: U.S. Geological Survey 

Scientific Investigations Report 2012–5212, 20 p.

EXPLANATION

Limits of the study area

Flood-inundation area

USGS streamgage and number 03382200

0 5 MILES

0 5 KILOMETERS

13 Illinois or Kentucky State route marker

U.S. route marker 45

Sheet 2. Flood inundation map of the Saline and Wabash Rivers, Illinois, corresponding to a gage height of 36 feet at U.S. Geological Survey streamgage number 03381700, Ohio River at Old Shawneetown, Illinois-Kentucky. 

GALLATIN COUNTY

HARDIN COUNTY

SALINE COUNTY

POPE COUNTY

SALINE COUNTY

GALLATIN COUNTY