Clear-Water Contraction Scour at Selected Bridge Sites in the Black Prairie Belt of the Coastal Plain in Alabama, 2006
Scientific Investigations Report
2007-5260
Prepared in cooperation with the Alabama Department of Transportation
By: K.G. Lee and T.S. Hedgecock
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Abstract
The U.S. Geological Survey, in cooperation with the Alabama Department of Transportation, made observations of clear-water contraction scour at 25 bridge sites in the Black Prairie Belt of the Coastal Plain of Alabama. These bridge sites consisted of 54 hydraulic structures, of which 37 have measurable scour holes. Observed scour depths ranged from 1.4 to 10.4 feet. Theoretical clear-water contraction-scour depths were computed for each bridge and compared with observed scour. This comparison showed that theoretical scour depths, in general, exceeded the observed scour depths by about 475 percent. Variables determined to be important in developing scour in laboratory studies along with several other hydraulic variables were investigated to understand their influence within the Alabama field data. The strongest explanatory variables for clear-water contraction scour were channel-contraction ratio and velocity index. Envelope curves were developed relating both of these explanatory variables to observed scour. These envelope curves provide useful tools for assessing reasonable ranges of scour depth in the Black Prairie Belt of Alabama.
Suggested Citation
Lee, K., Hedgecock, T., 2008, Clear-Water Contraction Scour at Selected Bridge Sites in the Black Prairie Belt of the Coastal Plain in Alabama, 2006: U.S. Geological Survey Scientific Investigations Report 2007-5260, viii, 57 p., https://doi.org/10.3133/sir20075260.
ISSN: 2328-0328 (online)
Study Area
| Publication type | Report |
|---|---|
| Publication Subtype | USGS Numbered Series |
| Title | Clear-Water Contraction Scour at Selected Bridge Sites in the Black Prairie Belt of the Coastal Plain in Alabama, 2006 |
| Series title | Scientific Investigations Report |
| Series number | 2007-5260 |
| DOI | 10.3133/sir20075260 |
| Year Published | 2008 |
| Language | ENGLISH |
| Publisher | Geological Survey (U.S.) |
| Contributing office(s) | Alabama Water Science Center |
| Description | viii, 57 p. |
| Time Range Start | 2006-01-01 |
| Time Range End | 2006-12-31 |