thumbnail

Assessing potential scour using the South Carolina bridge-scour envelope curves

Fact Sheet 2016-3065

Prepared in cooperation with the South Carolina Department of Transportation
By:
, , and ORCID iD
https://doi.org/10.3133/fs20163065

Links

Summary

Bridge-scour equations presented in the Federal Highway Administration Hydraulic Engineering Circular No. 18 reflect the current state-of-the practice for predicting scour at bridges. Although these laboratory-derived equations provide an important resource for assessing scour potential, there is a measure of uncertainty when applying these equations to field conditions. The uncertainty and limitations have been acknowledged by laboratory researchers and confirmed in field investigations.

Because of the uncertainty associated with bridge-scour equations, HEC-18 recommends that engineers evaluate the computed scour depths obtained from the equations and modify the resulting data if they appear unreasonable. Perhaps the best way to evaluate the reasonableness of predicted scour is to compare it to field measurements of historic scour. Historic field data show scour depths resulting from high flows and provide a reference for evaluating predicted scour. It is rare, however, that such data are available at or near a site of interest, making the evaluation of predicted scour as compared to field data difficult if not impossible. Realizing the value of historic scour measurements, the U.S. Geological Survey (USGS), in cooperation with the South Carolina Department of Transportation (SCDOT), conducted a series of three field investigations to collect historic scour data with the goal of understanding regional trends of scour at riverine bridges in South Carolina.

Historic scour measurements, including measurements of clear-water abutment, contraction, and pier scour, as well as live-bed contraction and pier scour, were made at more than 200 bridges. These field investigations provided valuable insights into regional scour trends and yielded regional bridge-scour envelope curves that can be used as supplementary tools for assessing all components of scour at riverine bridges in South Carolina.

The application and limitations of these envelope curves were documented in four reports. Because each report addresses different components of bridge scour, it was recognized that there was a need to develop an integrated procedure for applying the envelope curves to help assess scour potential at riverine bridges in South Carolina. The result of that effort is detailed in Benedict and others (2016) and summarized in this fact sheet.

Suggested Citation

Benedict, S.T., Feaster, T.D., and Caldwell, A.W., 2016, Assessing potential scour using the South Carolina bridge-scour envelope curves: U.S. Geological Survey Fact Sheet 2016-3065, 2 p., http://dx.doi.org/10.3133/fs20163065.

ISSN: 2327-6932 (online)

Study Area

Additional publication details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Assessing potential scour using the South Carolina bridge-scour envelope curves
Series title:
Fact Sheet
Series number:
2016-3065
DOI:
10.3133/fs20163065
Year Published:
2016
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Reston, VA
Contributing office(s):
South Atlantic Water Science Center
Description:
2 p.
Country:
United States
State:
South Carolina
Online Only (Y/N):
Y
Additional Online Files (Y/N):
Y