SGER: The Aftermath of Hurricane Floyd: Assessment of the Geomorphic Effectiveness of the 1999 Flood on the Tar River, North Carolina

East Carolina University, Greenville NC

Investigators

Abstract

Because of the infrequent occurrence and the difficulty of recognizing individual events in the stratigraphic record, few studies have examined the impacts of individual, large flood events on floodplain sedimentation. Although a considerable amount of research has demonstrated that a strong relationship exists between moderate flow events and sediment transport and channel morphology, the role of large floods in landscape modification remains uncertain. The extraordinary floods of September 1999 in eastern North Carolina resulted from hurricanes Dennis and Floyd provide an unusual opportunity to examine the geomorphic effectiveness of a low frequency, high magnitude flood. The proposed study examines the magnitude and spatial variability of floodplain sedimentation along the Tar River, North Carolina by (1) measuring and mapping spatial patterns of sedimentation, floodplain scour, and particle size, (2) linking these patterns to floodplain characteristics, (3) comparing the field data with sediment loads measured by the U.S. Geological Survey, and (4) quantifying the storage and location of several sediment-associated contaminants in the flood deposits. Field data will be collected from about 100-150 sample sites along five transects across the Tar River. Particle size analysis, chemical analysis, and spatial analysis will be applied to analyze these data. The significance of the project is to provide a useful data set that can rarely be collected. The data and the associated research will help improve our understanding of basic sediment transport and deposition dynamics during rare floods and will allow comparisons with the dynamics of rare floods on more controlled river systems. The research will also provide additional evidence necessary to understand the importance of large, catastrophic events in the sedimentary record.