Floods in North and South Dakota: Frequency and magnitude

The magnitude of a flood of a selected frequency for any point in the two states may be determined by methods outlined in this report, with two limitations. These methods are not applicable for regulated streams or for small-drainage areas (in general, less than 100 square miles). The determination of the magnitude of a flood of a selected frequency in the two-state area is accomplished by the use of composite frequency curves for 2 flood regions and curves showing variation of mean annual flood with drainage area for 9 hydrologic areas and 10 main-stem streams.

These curves are based on all flood data collected in North and South Dakota with some use made of records from adjoining states. These data are tabulated in the report.

Also included in the report is a tabulation of maximum flood experiences at gaging stations and outstanding floods at many miscellaneous sites.