Factors affecting accuracy of slope-area discharge determination of the September 1992 flood in Raven Fork, Western North Carolina

For the flood of September 10, 1992, in Raven Fork, Swain County, North Carolina, a peak discharge of 460 cubic meters per second was computed by using the slope-area method. Accuracy of this determination depends on suitability of the selected reach and, in particular, selection of Manning's roughness coefficients, interpretation of the high-water marks, number and placement of cross sections, presence of large expansions or contractions, state-of-flow transitions, and magnitude of the change in water-surface elevation. Some of these factors can contribute to greater uncertainties for measurements in steep mountain streams than for measurements in streams with flatter gradients.