Climatology and Hydrology of Eastern North Carolina and Their Effects on Creating the Flood of the Century

Abstract

Hurricane Floyd crossed eastern North Carolina on September 15 and 16, 1999, causing the largest disaster in the State's history. The majority of the damage was caused by flooding associated with heavy rainfall rather than by high winds or coastal erosion. The rainfall produced a flood that exceeded the predictions for the 100 year event, catching most of the residents of the region by surprise. The general perception was that the region had seen hurricanes of that magnitude before and that they had not produced such extreme floods. This particular flood occurred because hurricane Floyd arrived less than two weeks after hurricane Dennis, which dropped up to 10 inches of rain on the region, saturating the soil and raising river levels to the bankfull stage. When hurricane Floyd dropped an additional 8-16 inches, the likelihood of a severe flood was enhanced. There are a number of physical
features of eastern North Carolina that contributed to making this flood so severe. These include:
the shape of the drainage systems; the topography of the coastal plain; the characteristics of the soils;
and the land-use on the coastal plain. These factors combine with precipitation to produce hydrologic
conditions that are highly variable, as these factors vary in time and space. When these factors come
together in certain unique ways, extreme events, such as the flood associated with hurricane Floyd,
occur.