From the Abstract: "The magnitude and frequency of floods from gaged and ungaged drainage areas in California, for any recurrence interval from 2 to 100 years, can be estimated by use of the method presented. Equations relating flood magnitudes of selected frequency to basin characteristics such as drainage area, precipitation, and altitude were developed for six regions in the State. Nomographs are included for solution of the equations. The regression equations were developed for streams that have natural flow or flows not substantially affected by storage."
Water-Resources Investigations 77-21
U.S. Geological Survey: https://www.usgs.gov/