SCOUR AT SELECTED BRIDGE SITES IN ALASKA

General scour at bridge crossings and local scour at bridge piers were measured at nine bridge sites in Alaska during the study period 1965-72. A detailed description of the physical setting, hydraulic characteristics, and channel geometry at low and high flows is given for each site to assist the reader in developing a background for the scour phenomenon in various situations. Flood discharges, during which scour data were collected, had recurrence intervals which range from approximately two years at some sites to about 100 years on the Tanana River at Nenana. General scour was minimal at crossings with no channel contraction. Measured general scour in contracted openings at three sites indicated mean depth of flow in contracted openings can be calculated by two established scour formulas to within 10% of the actual mean depth. Measured local equilibrium scour depth and bed material sizes at bridge piers were used to modify an existing pier scour formula to estimate maximum local equilibrium scour depth at round or pointed-nosed piers alined with the flow. The data suggest local equilibrium scour depth at piers during a mean annual flood is approximately as great as that which occurs during floods of greater magnitude.

  • Supplemental Notes:
    • Prepared in cooperation with Alaska State Dept. of Highways, Juneau, and Federal Highway Administration, Washington, D.C. Report on Water-resources Investigations.
  • Corporate Authors:

    U.S. Geological Survey

    F Street Between 18th and 19th Street, NW
    Washington, DC    20244

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  USA  20590

    Alaska Department of Highways

    P.O. Box 1467
    Juneau, AK  USA  99801
  • Authors:
    • Norman, V W
  • Publication Date: 1975-11

Media Info

  • Features: Figures; Tables;
  • Pagination: 171 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00093956
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: USGS-WRD-76-001 Final Rpt., USGS-WRI-32-75
  • Files: NTIS, TRIS, USDOT, STATEDOT
  • Created Date: Mar 10 1976 12:00AM