Techniques for Estimating Flood-Depth Frequency Relations on Natural Streams in Georgia

Regional relations are defined for estimating the depth of floods having recurrence intervals of 10, 50, and 100 years on streams with natural flow in Georgia. Multiple-regression analysis of station data is used to define the relations between flood depths and frequency for streams draining from 1 to 1,000 square miles, and for 10 climatological and physical basin characteristics. The analysis indicates that the drainage area of the basin is the most significant variable. Five regions having distinct flood-depth frequency characteristics are delineated. The developed relations, expressed as equations and graphs, are considered usable for any site in Georgia where the drainage area is between 1 and 1,000 square miles, and the flow is natural; exceptions include streams that are urbanized, regulated, tide affected, channelized, or where manmade structures significantly affect peak stages.