USGS: OFR 2003-295 Contents

Open-File Report 2003-295

Trends of Abutment-Scour Prediction Equations Applied to 144 Field Sites in South Carolina

Abstract
Introduction
Purpose and Scope
Previous Investigations
South Carolina Field Data
Sediment Samples
Hydraulic Data
Contraction and Pier Scour in the Abutment Area
Characteristics of the Piedmont and Coastal Plain Provinces
Envelope Curves of Field Data
South Carolina Bridge-Scour Database
Abutment Scour Prediction Equations
Original Froehlich Equation
Modified Froehlich Equation
Sturm Equation
Maryland Equation
HIRE Equation
Young Equation
Development of Two-Dimensional Flow Models
Summary
Selected References
Appendix A: South Carolina bridge-scour study sites and reference numbers in figure 1
Appendix B: Description of spreadsheets used in the equation assessments
Appendix C: Description of compiled data including WSPRO tube-velocity data, soil-boring data, selected abutment-scour data, and threshold velocity data
Appendix D: A comparison of selected methods for estimating sediment threshold velocities
Appendix E: Determination of soil erosion rates at five sites in South Carolina
Appendix F: A 2–D numerical model study on flow past the abutments of highway bridges in South Carolina

Map showing location of physiographic provinces and bridge-scour study sites in South Carolina

2 – 5. Graphs showing:

Median grain size of the original and second sediment samples
Relation of observed clear-water abutment-scour depth and the 100-year-flow embankment length in the Piedmont of South Carolina
Relation of observed clear-water abutment-scour depth and the 100-year-flow embankment length for the Coastal Plain of South Carolina
Relation of the predicted 100-year-flow abutment-scour depth and embankment length compared with the envelope of observed abutment scour for selected sites in the Piedmont of South Carolina
Sketch showing embankment length and obstructed flow area determined by projection of the bridge cross section onto the approach cross section
Graph showing field observations of abutment-scour depth and predicted abutment-scour depth for the 100-year flow, computed with the original Froehlich equation with the factor of safety, for selected sites in the Piedmont and Coastal Plain of South Carolina
Sketch showing determination of embankment length blocking live flow
Graph showing field observations of abutment-scour depth and predicted abutment-scour depth for the 100-year flow, computed with the modified Froehlich equation with the factor of safety, for selected sites in the Piedmont and Coastal Plain of South Carolina

10–11. Sketches showing:

Approach cross section with a well-defined low-flow channel, identifying areas used to determine hydraulic properties
Approach cross section for swampy site with no well-defined low-flow channel, identifying areas used to determine hydraulic properties
Graph showing field observations of abutment-scour depth and predicted abutment-scour depth for the 100-year flow, computed with the Sturm equation with the factor of safety, for selected sites in the Piedmont and Coastal Plain of South Carolina
Sketch showing approach cross section for swampy site with no well-defined low-flow channel, identifying the channel used in applying the Maryland equation

14–15. Graphs showing:

Field observations of abutment-scour depth and predicted abutment-scour depth for the 100-year flow, computed with the Maryland equation with the factor of safety, for selected sites in the Piedmont and Coastal Plain of South Carolina
Field observations of abutment-scour depth and predicted abutment-scour depth for the 100-year flow, computed with the HIRE equation for selected sites in the Piedmont and Coastal Plain of South Carolina
Sketch showing definition of scour hole velocities, depths, and areas for equation 20
Graph showing field observations of abutment-scour depth and predicted abutment-scour depth for the 100-year flow, computed with the Young equation for selected sites in the Piedmont and Coastal Plain of South Carolina

18–22. Sketches showing:

Topography of abutment scour at structure 014020100300 on S.C. Route 201 crossing the Little River in Abbeville County, South Carolina
Topography of abutment scour at structure 254036300100 on S.C. Route 363 crossing the Coosawhatchie River in Hampton County, South Carolina
Topography of abutment scour at structure 277008700100 on Road S–87 crossing the Coosawhatchie River in Jasper County, South Carolina
Topography of abutment scour at structure 362017600400 on U.S. Route 176 crossing Indian Creek in Newberry County, South Carolina
Topography of abutment scour at structure 367008100200 on Road S–81 crossing the Enoree River in Newberry County, South Carolina

Range of selected properties for clear-water abutment-scour data collected in the Piedmont and Coastal Plain of South Carolina
Sites for which two-dimensional flow models were developed
Selected basin characteristics for sites with two-dimensional flow models
Selected abutment data for sites with two-dimensional flow models