OVERVIEW OF THE SEPTEMBER-OCTOBER 1999 FLOODING IN THE TAR RIVER BASIN, NORTH CAROLINA

HARPER, Stephen B. and SPRUILL, Richard K., Department of Geology, East Carolina University, Greenville, NC 27858, harpers@mail.ecu.edu.

    Four rainfall events in the months of September-October 1999 triggered unprecedented levels of upstream flash flooding in the tributaries of the Tar River and downstream flooding in the lower portions of the Tar River Basin. These rainfall events were Hurricane Dennis (6-9 inches) in early September, Hurricane Floyd (9-15 inches) in mid September, a non-tropical storm-related rainfall event (2-6 inches) in late September, and Hurricane Irene (3-9 inches) in mid October. The most intense flash flooding and prolonged downstream flooding resulted from the rainfall generated by Hurricane Floyd.
    Tributaries to the Tar River experienced flash flooding in response to all four rainfall events. The flood peaks for Fishing Creek and Conetoe Creek, resulting from Hurricane Floyd, exceeded the historical high stages of 19.60 and 15.50 feet respectively for these two locations. Hardee, Green Mill, and Chicod Creeks in the Greenville area experienced similar magnitudes of flash flooding and also experienced back water flooding near their confluences with the Tar River.
    On the Tar River flood peaks generated by Hurricane Floyd exceeded all previous historically recorded flood events at Rocky Mount, Tarboro, and Greenville, NC. by 5.78, 7.51, and 5.22 feet respectively. The locations along the Tar River with the highest flood peaks corresponded spatially to the areas of highest rainfall. Rocky Mount, Tarboro, and Greenville, all of which experienced 10-18 inches of rainfall, also experienced the highest flood peaks relative to any previously recorded flood events. The correspondence of total rainfall amounts and peak levels of flooding and the cumulative flood impact from rainfall from Hurricanes Floyd and Dennis suggest that the extreme magnitude of the flooding along the Tar River and its tributaries resulted from unusual meteorological conditions.
    The Tar River at Tarboro and Greenville remained in flood stage from September 09 and 10 to October 07 and 09 and crested on September 20 and 21 respectively. Rainfall from Hurricane Irene renewed downstream flooding on the Tar River at Tarboro from October 19-27 and at Greenville from October 19-29.