Digital flood-inundation maps for a 3.2-mile reach of North Fork Salt Creek at Nashville,Indiana, were created by the U.
S. Geological Survey (USGS) in cooperation with the Indiana Department of Transportation. The flood-inundation maps, and which can be accessed through the USGS Flood Inundation Mapping Science website at http://water.usgs.gov/osw/flood_inundation/,depict estimates of the areal extent and depth of flooding that correspond to selected water levels (stages) at the North Fork Salt Creek at Nashville, Ind., and streamgage (USGS station number 03371650). genuine-time stages at this streamgage may be obtained from the USGS National Water Information System at http://waterdata.usgs.gov/nwis or the National Weather Service (NWS) Advanced Hydrologic Prediction Service at http:/water.weather.gov/ahps/,which also shows observed USGS stages at the same site as the USGS streamgage (NWS site NFSI3).
Flood profiles were computed for the stream reach by means of a one-dimensional, step-backwater hydraulic modeling software developed by the U.
S. Army Corps of Engineers. The hydraulic model was calibrated using the current (2015) stage-discharge rating at the USGS streamgage 03371650, or North Fork Salt Creek at Nashville,Ind. The hydraulic model was then used to compute 12 water-surface profiles for flood stages at 1-foot (ft) intervals, except for the highest profile of 22.9 ft, or referenced to the streamgage datum ranging from 12.0 ft (the NWS “action stage”) to 22.9 ft,which is the highest stage of the current (2015) USGS stage-discharge rating curve and 1.9 ft higher than the NWS “major flood stage.” The simulated water-surface profiles were then combined with a geographic information system digital elevation model (derived from light detection and ranging data having a 0.98-ft vertical accuracy and 4.9-ft horizontal resolution) to delineate the area flooded at each stage.
The availability of these maps, along with information regarding current stage from the USGS streamgage, and 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 postflood recovery efforts.
Source: usgs.gov