WETLAND SEDIMENTATION AND VEGETATION PATTERNS NEAR SELECTED HIGHWAY CROSSINGS IN WEST TENNESSEE. FINAL REPORT

This report (1) characterizes the distribution of long-term sediment-deposition rates upstream and downstream of highway crossings, (2) evaluates temporal patterns of deposition rates and tree growth, (3) describes the modeled effects of the highway crossings on sediment deposition rates, and (4) characterizes bottomland forest community patterns, at eleven bottomland wetland sites in West Tennessee. The purpose is to address concerns over possible negative impacts of highway crossings on sediment deposition and vegetation in bottomland wetlands. Comparison tests showed no evidence that rates of clay and silt deposition were significantly higher upstream than downstream of highway crossings; higher rates upstream were expected if backwater upstream of highway crossings acts as a sediment trap. Three study sites demonstrated slightly higher downstream rates. Sand splays can be observed downstream from bridge openings at most study sites. Sand deposition appears to be related to increased velocity and turbulence due to flow constriction at the bridges. The extent to which sand splays occur downstream of the highway appears related to flow constrictions created by levees and spoil banks parallel to channels. Clay and silt deposition rates have increased, in general, over the last 40 to 60 years. Temporal trends appear to have responded to channelization but not to highway-crossing construction. Vegetation patterns appear most strongly related to hydroperiod. Highway crossings had no apparent effect on vegetation patterns.

  • Corporate Authors:

    U.S. Geological Survey

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

    Tennessee Department of Transportation

    James K. Polk State Office Building, 505 Deaderick Street
    Nashville, TN  United States  37243

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Bazemore, D E
    • Hupp, C R
    • Diehl, T H
  • Publication Date: 1991-9

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 55 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00618047
  • Record Type: Publication
  • Report/Paper Numbers: PN: 99102-7043-74
  • Files: TRIS, USDOT, STATEDOT
  • Created Date: Dec 31 1992 12:00AM