American Society of Civil Engineers

Trends in Live-Bed Pier Scour at Selected Bridges in South Carolina

by Stephen T. Benedict, (Hydrologist, U.S. Geological Survey, 405 College Avenue, Clemson, SC 29631. E-mail: and Andral W. Caldwell, (Hydrologist, U.S. Geological Survey, 720 Gracern Road, Columbia, SC 29210. E-mail:
Section: Bridge Scour, pp. 95-104, (doi:

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Document type: Conference Proceeding Paper
Part of: Scour and Erosion
Abstract: The U.S. Geological Survey, in cooperation with the South Carolina Department of Transportation, used ground-penetrating radar to collect measurements of live-bed pier scour at 78 bridges in the Piedmont and Coastal Plain physiographic provinces of South Carolina. The 141 measurements of live-bed pier-scour depth ranged from 0.5 to 5.1 meters. Using hydraulic data estimated with a one-dimensional flow model, predicted live-bed scour depths were computed with scour equations from the Hydraulic Engineering Circular 18 and compared with measured scour. This comparison indicated that predicted pier-scour depths generally exceeded the measured pier-scour depths. At times, predicted pier-scour depths were excessive with overpredictions as large as 7.0 meters. Relations in the live-bed pier-scour data also were investigated, leading to the development of an envelope curve for assessing the upper-bound of live-bed pier scour using pier width as the primary explanatory variable. The envelope curve developed with the field data has limitations, but it can be used as a supplementary tool for assessing the potential for live-bed pier scour in South Carolina. This paper will present findings related to the field investigation of live-bed pier scour. A companion paper presents findings related to live-bed contraction scour that was studied during the same field investigation.

ASCE Subject Headings:
South Carolina