The Relationship Between Drainage Basin Area and Annual Peak-Flood Seasonality in the Southeastern United States

This study examines relationships between drainage basin area and flood seasonality in the southeastern United States. To assess this relationship, a flood seasonality analysis of annual peak flood series for 84 individual drainage basins is completed, identifying five distinct annual peak-flood seasonality regions: the Tennessee, the Gulf Coast, Peninsular Florida, the Carolinas, and the Georgia Coastal Plain. These results confirm previous research except for the Carolina region, which possesses no dominant season in annual peak-flood frequency. Further statistical analysis indicates that the Georgia Coastal Plain is the only region of the five with a statistically significant relationship between drainage basin area and annual peak-flood seasonality. The statistical relationships for this region are interpreted as spring annual peak floods occurring more frequently on larger drainage basins because of high soil moisture and frequent extratropical-cyclone passage. Weak, significant statistical relationships exist between drainage basin area and annual peak-flood seasonality when all streams are placed in a single data set representing the entire southeastern United States. These results suggest the need for a wide range in drainage-basin area to identify a relationship between drainage-basin area and annual peak-flood seasonality.