Magnitude and frequency of floods in Nebraska
Estimates of flood characteristics with recurrence intervals up to 100 years can be obtained at most sites in Nebraska by use of techniques presented in this report. Instructions, equations, and graphs are presented to aid the design engineer in estimating the magnitude and frequency of floods. For natural-flow streams, the estimating equations and graphical solutions are based on regional relations between floods of a specific return period and selected basin characteristics. Nebraska was subdivided into five hydrologic regions by means of regressions and residuals from the regressions. The boundaries of Regions 1 and 2 were determined to a great extent by differences in soil type. The divisions between Region 2 and Region 4 were also determined by differences in soil type. Boundaries of Region 3 and Region 5 are along or near basin divides. Flood magnitude and frequency solution diagrams are presented for major controlled streams such as the North Platte, South Platte, Platte, and Republican Rivers. Flood information on small controlled streams is limited to available station data. Flood characteristics are tabulated for 303 gaging stations having 13 or more years of record. These flood characteristics provide the best information on floods at these gaged sites. Observed maximum flood peaks at 303 gaging stations with 13 or more years of record and significant peaks at 57 short-term stations and 31 miscellaneous sites are useful in designing flood-control works for maximum safety from flood damage. Comparison is made with maximum observed floods in the United States.