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

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

“…This report includes the flood elevations, areas of bridge openings for selected high-water conditions, average velocities through the bridges, and backwater computations for the proposed bridge conditions reported by Price and Hess (1987). The location of the proposed bridge, cross sections used in flood routing, relocated channel, floodway, and 100-year boundary used in the analysis and described in this report are shown in figure 1.…”

“…Miscellaneous high-water information has been obtained by the USGS for major floods from 1961 to 1987 at several bridge crossings of Nancy Creek from its mouth to Tilly Mill Road. Data used in the previous study (Price and Hess, 1987) were collected during a field reconnaissance of the study reach by USGS personnel in 1987. The Manning's V values used by Price and Hess (1987) also were used in the step-backwater analyses for this study.…”

“…Data used in the previous study (Price and Hess, 1987) were collected during a field reconnaissance of the study reach by USGS personnel in 1987. The Manning's V values used by Price and Hess (1987) also were used in the step-backwater analyses for this study.…”

“…The Manning "n" roughness values used in the step-backwater analysis were initially assumed to be the same as those used by Price and Hess (1987). The "n" values betweeen Wieuca Road and Windsor Parkway were then adjusted until the step-backwater analysis reproduced the elevation-discharge relation at Windsor Parkway (fig.…”

“…In 1987, U.S. Geological Survey (USGS), in cooperation with the Georgia Department of Transportation (GDOT), Highway Division, began a study on the flood-flow characteristics of Nancy Creek at the proposed Georgia Highway 400 Extension near Atlanta, Ga. The initial results of that study were documented in a report by Price and Hess (1987) which described the flood-flow characteristics of Nancy Creek for floods having recurrence intervals of 2-, 10-, 25-, 50-, and 100-years for the following conditions:…”