Clear-water abutment and contraction scour in the Coastal Plain and Piedmont Provinces of South Carolina, 1996-99

Water-Resources Investigations Report 2003-4064

Prepared in cooperation with the South Carolina Department of Transportation



The U.S. Geological Survey, in cooperation with the South Carolina Department of Transportation, collected observations of clear-water aburment and contraction scour at 146 bridges in the Coastal Plain and Piedmont of South Carolina. Scour depths ranged from 0 to 23.6 feet. Theoretical scour depths were computed at each bridge and compared with observed scour. This comparison showed that theoretical scour depths, in general, exceeded the observed scour depths and often were excessive. A comparison of field data with dimensionless relations for laboratory data showed that the range of dimensionless variables used in laboratory investigations was outside of the range for field data in South Carolina, suggesting laboratory relations may not be applicable to field conditions in South Carolina. Variables determined to be important in developing scour within laboratory studies were investigated to understand their influence within the South Carolina field data, and many of these variables appeared to be insignificant under field conditions found in South Carolina. The strongest explanatory variables were embankment length, geometric-contraction ratio, approach velocity, and soil cohesion. Envelope curves developed with the field data are useful tools for assessing reasonable ranges of scour depth in South Carolina. These tools are simple to apply and are an improvement over the current methods for predicting theoretical scour.

Data from this study have been compiled into a database that includes photographs, figures, observed scour depths, theoretical scour depths, limited basin characteristics, limited soil data, and theoretical hydraulic data. The database can be used to compare studied sites with unstudied sites to assess the potential for scour at the unstudied sites. In addition, the database can be used to assess the performance of various theoretical methods for predicting clear-water abutment and contraction scour.

Suggested Citation

Benedict, S.T., 2016, Clear-water abutment and contraction scour in the Coastal Plain and Piedmont Provinces of South Carolina, 1996-99: U.S. Geological Survey Water Resources Investigation Report 2003-4064,

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Data Assumptions
  • Site Selection
  • Techniques for the Collection and Interpretation of Field Data
  • Estimating Hydraulic Data.
  • Development of Theoretical Bridge-Scour Database
  • Variables Influencing Abutment Scour
  • Abutment Scour in the Piedmont
  • Abutment Scour in the Coastal Plain
  • Effect of Upstream Channel Alignment on Abutment Scour
  • Guidance for Assessing Abutment-Scour Depth Using the Envelope Curves
  • Guidance for Assessing Abutment-Scour Hole Location, Width, and Shape
  • Clear-Water Contraction Scour in the Piedmont
  • The South Carolina Bridge-Scour Database
  • Summary
  • Selected References
  • Appendix A: Explanation of Variables in the South Carolina Bridge-Scour Database
  • Appendix B: South Carolina Bridge-Scour Study Sites and Reference Numbers for Figures 1, 5, and 6.

Additional publication details

Publication type:
Publication Subtype:
USGS Numbered Series
Clear-water abutment and contraction scour in the Coastal Plain and Piedmont Provinces of South Carolina, 1996-99
Series title:
Water-Resources Investigations Report
Series number:
Version 1.0: Originally posted in 2003; Version 1.1: August 31, 2016
Year Published:
U.S. Geological Survey
Publisher location:
Reston, VA
Contributing office(s):
South Atlantic Water Science Center
Report: x, 137 p.; Appendix A; Database
United States
South Carolina
Other Geospatial:
Coastal Plain, Piedmont Province
Online Only (Y/N):
Additional Online Files (Y/N):