Flood-flow characteristics of Nancy Creek at Georgia Highway 400 extension near Atlanta, Georgia

The Highway Division, Georgia Department of Transportation, plans the extension of Georgia Highway 400 from Interstate 285 southward to Interstate 85. As part of this extension, the Highway Division plans construction of a bridge crossing Nancy Creek near Atlanta, Georgia. The U.S. Geological Survey, in cooperation with the Highway Division, determined the flood flow characteristics of Nancy Creek near the bridge crossing. The flood frequency, elevation discharge relation, flood profiles, floodway, and flood flow effects were determined. The maximum backwater effect for the proposed bridge and relocated channel was 0.2 ft for the 100-yr flood. The relocated channel will drastically shorten flow length near the proposed State Highway 400 extension and reduce the 100-yr flood elevation between one and two ft from existing conditions between the proposed site and Windsor Parkway. (Author's abstract)