Summary

Description

The lower Roanoke River corridor in North Carolina contains a floodplain of national significance. Data from a network of 1 streamflowmeasurement site, 13 riverstage sites, 13 floodplain waterlevel sites located along 4 transects, and 5 in situ waterquality monitoring sites were used to characterize temporal and spatial variations of floodplain and river water levels during 1997 2000 and to describe dissolved oxygen conditions in the lower Roanoke River for the period 1998 2001. Major differences in the relation of floodplain inundation to flow occurred both among sites at a given transect and among transects. Several floodplain sites were inundated for the full range of flow conditions measured during the study. These included one site on the Big Swash transect at about river kilometer 119; one site on the Broadneck Swamp transect river kilometer 97, which was inundated 91 percent of the time during the study; one site on the Devils Gut transect river kilometer 44, which was inundated throughout the study; and three sites on the Cow Swamp transect near river kilometer 10. Dissolvedoxygen concentrations typically decrease with increasing distance from Roanoke Rapids Dam. During the 1998 2001 study period, the median dissolvedoxygen concentration at Halifax river kilometer 187, the upstream most station, was 8.4 milligrams per liter, and the median concentration at the downstreammost station NC45, bottom sensor; river kilometer 2.6 was 6.6 milligrams per liter.