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35 .. August 1955 . September 1999 30 ~ 25 '" '-' ~ '" -_ 20 ~ ~ '" ~ '" '" '" 15 ~ '" >- '" '" ::;; 10 5 0 2 2 3 4 2 3 5 6 Tar-Pamlico River Basin 1 Rocky Mount Z Enfield 3 Greenville 4 Washington Neuse River Basin 1 Raleigh 2 Goldsboro 3 Kinston 4 Wilson 5 New Bern Cape Fear River Basin 1 Fayetteville 2 Clinton 3 Wilmington 4 South port Other locations 1 Edenton Z Elizabeth City 3 Hoffman Forest (19991 Maysvilla 119551 4 Morehead City 5 Lumberton 6 Whiteville Figure 6. August 1955 and September 1999 monthly rainfall at selected sites in the Tar-Pamlico, Neuse, and Cape Fear River Basins, and at selected other sites. Hurricane Floyd Rainfall Compared to Hurricane Fran (1996) Rainfall Hurricane Fran in September 1996 resulted in extensive flooding in many of the same areas affected by Hurricane Floyd (Bales and Chil- dress, 1996). Flood recurrence intervals were in excess of 100 years at a number oflocations in the upper Tar-Pamlico Basin, upper Neuse Basin, and throughout much of the Cape Fear River Basin. Rainfall amounts associated with Hurricane Fran were greater than those ofHurrieane Floyd in the upper Tar (Oxford) and upper Neuse (Durham and Raleigh) River Basins (table I). Hurricane Fran rainfall also was greater than Hurricane Floyd rainfall in the upper Cape Fear River Basin (Chapel Hill, table I), includ- ing the Haw and Deep River Basins, where Hurricane Fran flood recur- rence intervals were generally between 100 and 500 years. In addition, Hurricane Fran rainfall exceeded Hurricane Floyd rainfall near the coast at Morehead City and Hoffman Forest (table I). However, with these few exceptions, Hurricane Floyd rainfall was much greater than rainfall from Hurricane Fran. For example, at Rocky Mount and Kinston, Hurrieane Floyd rainfall was almost three times greater than Hurricane Fran rainfall (table I). The highest reported consecutive 24-hour rainfall associated with Hurricane Fran was 6,70 inches at Franklinton (National Climatic Data Center, 1996b), which is about 10 miles west of Louisburg (fig. 3). This rainfall amount corresponds to approxi- mately a 24-hour 25-year rainfall event, compared to Hurricane Floyd rainfall, which was much greater than a 24-hour lOa-year rainfall event (table 2). The Relation of Rainfall to Flooding As a general rule, it should not be assumed that a lOa-year rain event would result in a lOa-year flood. Conditions prior to a particular storm affect the amount of runoff that Two Months of Flooding in Eastern North Carolina, September-October 1999