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Impact of the proposed I-326 crossing on the 500-year flood stages of the Congaree River near Columbia, South Carolina

Water-Resources Investigations Report 84-4280

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Abstract

A two-dimensional finite-element surface water flow modeling system based on the shallow water equations was used to study the hydraulic impact of the proposed Interstate crossing on the 500-year flood. Infrared aerial photography was used to define regions of homogeneous roughness in the flood plain. Finite-element networks approximating flood plain topography were designed using elements of three roughness types. High water marks established during an 8-year flood that occurred in October 1976 were used to calibrate the model. The 500-year flood (630,000 cu ft/sec) was simulated using the dike on the left bank as the left boundary and the right edge of the flood plain as the right boundary. Simulations were performed without and with the proposed highway embankments in place. Detailed information was obtained about backwater effects upstream from the proposed highway embankments, changes in flow distribution resulting from embankments, and velocities in the vicinity of the bridge openings. The results of the study indicate that the four bridge openings in the right flood plain should be adequate to handle the 500-yr flood flow. Forty percent of the flow passes through the main channel bridge, while the remaining 60% of the flow passes through the three overflow bridges. Average velocities in the bridge openings ranged from 3.4 ft/sec to 6.9 ft/sec with a maximum vertically averaged velocity of 9.3 ft/sec occurring at the right edge of one of the overflow bridges. (Author 's abstract)

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Impact of the proposed I-326 crossing on the 500-year flood stages of the Congaree River near Columbia, South Carolina
Series title:
Water-Resources Investigations Report
Series number:
84-4280
Edition:
-
Year Published:
1984
Language:
ENGLISH
Publisher:
U.S. Geological Survey,
Description:
iv, 23 p. :ill., maps (some col.) ;28 cm.