This report provides methods for estimating flood characteristics at most sites where flood information may be needed for planning and design and summatizes the significant flood data and related information available on Wisconsin streams. Individual equations are presented for estimating flood discharges for selected recurrence intervals up to a 25-year flood for drainage areas 0.5 square miles and larger, a 50-year flood for drainage areas 20 square miles and larger, and a 100-year flood for drainage areas 50 square miles and larger. A ratio method is used for estimating a 50-year flood for drainage areas 0.5 to 20 square miles. The equations were defined from multiple-regression analysis of flood peak records and basin characteristics for 119 continuous-record gaging stations and 114 crest-stage partial-record stations in Wisconsin and adjoining States. Of the severai basin characteristics used in this study, only drainage area, main-channel slope, lake and marsh area, and areal factors were found to be statistically significant at the 99 percent effectiveness level for all flood frequencies. Solution of a hypothetical problem is given for using the flood-frequency equations. Graphs are presented for solution of flood discharges on regulated streams where the formulas are not applicable. Flood-frequency characteristics, 2-year flood to 100-year flood, and drainage basin characteristics for stations used in the multiple regression are presented in the appendices of this report.
