Prevention of Shoaling at Little Lake Harbor, Michigan. Hydraulic Model Investigation.
Abstract
Little Lake Harbor, Michigan, was constructed as a harbor of refuge for small craft on the south shore of Lake Superior. However, the existing breakwaters have not prevented a heavy influx of sediment into the entrance channel and shoaling makes navigation difficult and dangerous. A 1:75-scale (undistorted) hydraulic model, reproducing the harbor, breakwater structures, entrance channel, adjacent shoreline for 1 mile both east and west of the harbor, and underwater contours out to -30 ft, was used to investigate various plans proposed to minimize or eliminate channel shoaling. The model simulated wind waves, wave-generated currents, seiche action, seiche-generated currents, and the movement of sediment (by the use of a crushed coal tracer). From an analysis of prototype data on water-level variation in Lake Superior and the harbor basin, it was determined that seiche oscillations with periods near the inlet-bay Helmholtz period occurred frequently. These oscillations could generate velocities as high as 4.5 fps in the entrance channel, with a median velocity of 0.62 fps. Proposed measures to reduce channel shoaling were primarily concerned with the addition of a new structure on the east side of the entrance channel and/or extensions of the existing breakwaters.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1982
- Accession Number
- ADA120776
Entities
People
- James W. Mccoy
- William C. Seabergh