FLUME MEASUREMENTS OF SEDIMENT ERODIBILITY IN BOSTON HARBOR

To obtain in situ measurements of sediment erodibility in defined bottom shear stress environments, a portable, straight flume was built, tested, and deployed in the field for six experiments at three locations in Quincy Bay of Boston Harbor, Massachusetts. The flume had a 1.0-m-long inlet section, which included a boundary-layer trip and a roughened, plexiglass bottom; this design prevented erosion of the sediment bed in the boundary-layer-development region. Downstream of the inlet section was a 1.2-m-long sediment test section, which had a laboratory-verified, uniform bottom stress. In the absence of algal mats, the flume experiments on sites exhibiting a range of bed properties indicated quite uniform erodibility, with a critical shear stress of 0.10 +/- 0.04 Pa and an erosion rate constant of 3.2 +/- 0.0002 kg/sq m s Pa (R sq = 0.92, N = 17, where N is the total number of erosion rate measurements made in the absence of algal mats). The measured rates were consistent with those of many other in situ studies. Markedly reduced erodibility was observed in early October 1995 when the sediment was covered by a benthic diatom mat, and measured erosion rates were lessened by 50-80%. The possibility of depth-dependent sediment erodibility in near surface (top 3 mm) was investigated by calculating a set of depth-dependent erosion parameters. The parameters obtained suggested that both the critical shear stress and the erosion rate constant were depth-sensitive (both doubling by 1 mm into the sediment).

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/oclc/8672558
• Supplemental Notes:
  • This work was funded by the Office of Naval Research (Grant No. NOOO14-94-1-0752). Page Range: pp 998-1005
• Corporate Authors:

  American Society of Civil Engineers

  1801 Alexander Bell Drive
  Reston, VA  United States  20191-4400
• Authors:
  • Ravens, T M
  • Gschwend, P M
• Publication Date: 1999-10

Language

• English

Media Info

• Features: Appendices; Figures; References; Tables;
• Pagination: 8 p.
• Serial:
  • Journal of Hydraulic Engineering
  • Volume: 125
  • Issue Number: 10
  • Publisher: American Society of Civil Engineers
  • ISSN: 0733-9429
  • Serial URL: https://ascelibrary.org/journal/jhend8

Subject/Index Terms

• TRT Terms: Algae; Benthos; Depth; Erosion; Field tests; Flow; Flumes; Harbors; Marine deposits; Sediments; Shear stress; Turbidity
• Geographic Terms: Boston (Massachusetts); Quincy Bay
• Subject Areas: Environment; Marine Transportation; Terminals and Facilities;

Filing Info

• Accession Number: 00770130
• Record Type: Publication
• Contract Numbers: NOOO14-94-1-0752, BCS-9220663, W-908
• Files: TRIS
• Created Date: Oct 8 1999 12:00AM