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|Title:||Design for wave protection and prevention of shoaling, Geneva-on-the-Lake small-boat harbor, Ohio : hydraulic model investigation|
|Authors:||United States. Army. Corps of Engineers. Buffalo District.|
Bottin, Robert R.
|Publisher:||Hydraulics Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||Technical report (U.S. Army Engineer Waterways Experiment Station) ; HL-82-17.|
Abstract: A 1:60-scale undistorted hydraulic model of the lower reaches of Cowles Creek, the Ohio shoreline to the east and west of the creek mouth, the proposed small-boat harbor, and sufficient offshore area in Lake Erie to permit generation of the required test waves was used to investigate the design of certain proposed breakwater configurations with respect to wave protection and shoaling. The proposed improvements, as authorized in House Document No. 91-402, consisted of (A) breakwaters in Lake Erie, aggregating about 1,400 ft in length, with a riprapped spending beach between the entrance channel and the inner end of the west breakwater; (B) a 1,000-ft-long entrance channel, varying from 180 to 100 ft in width, 8 ft deep for the outer 500 ft and 6 ft deep for the inner 500 ft, extending from the 8-ft contour in the lake into the dock channel; (C) a 1, 500- ft-long, 100-ft-wide dock channel, 6 ft deep, widened to 200 ft at the junction with the entrance channel; and (D) development of recreational facilities. This plan was subsequently modified in the Reformulation Phase I General Design Memorandum study to include: (a.) breakwaters in Lake Erie aggregating about 1,050 ft in length; (b.) an 800-ft-long entrance, 100 ft wide and 8 ft deep; (c.) interior channels aggregating about 1,700 ft in length, 100 ft wide and 6 ft deep; (d.) a small-craft refuge area totaling about 0.9 acre in size; (e.) a mitigation plan including a water control structure, creation of about 5 acres of new wetlands, and expansion of an existing island to favor the establishment of waterfowl; and (f). development of related recreational fishing facilities. The reformulated plan was the one tested in the model study. A 60-ft-long wave generator, crushed coal sediment tracer material, a model circulation system, and an Automated Data Acquisition and Control System were utilized in model operation. It was concluded from test results that: (1.) For existing conditions, sediments and currents along the shoreline in the vicinity of the proposed harbor may move in either direction (east or west) depending on the incident wave direction. (2.) With the proposed harbor installed with no breakwaters (Base Test), rough and turbulent wave conditions existed in the harbor entrance during periods of storm-wave attack. (3.) With the proposed harbor installed with no breakwaters (Base Test), sediment deposited in the entrance channel. (4.) For the originally proposed improvement plan (Plan 1), significant overtopping of the breakwaters occurred resulting in excessive wave heights in the entrance and mooring areas. (5.) Of the improvement plans tested under initial test conditions (maximum swl of +4.4 ft), Plan 2F (150-ft extensions of the +8 ft elevation east and west breakwaters) appeared to be optimal with respect to wave protection, orientation of the navigation entrance, and construction costs (although several test plans met the established wave-height criteria). (6.) Of the improvement plans tested with the revised maximum swl of +5.3 ft, Plan 2H (200-ft extensions of the +8 ft elevation east and west breakwaters) appeared to be the most desirable with respect to wave protection. (7.) Discharges from the wetland area (adjacent to the proposed small-boat harbor) had little effect on wave heights in the harbor entrance for Plan 2H. (8.) Sediment accumulated against the outside of the breakwaters of Plan 2H, but did not enter the harbor entrance for any wave conditions tested. (9.) To prevent erosion and/or undermining of the water control structure, a revetment should be installed, or the structure should be constructed after the breakwaters are installed and the shoreline in the area stabilizes. (10.) To prevent waves from flanking the breakwaters, berms (el +12) tying the shoreward ends of the breakwaters to higher ground were required. (11.) Waves in the harbor generated by the model boat (boat wake) dissipated quickly and caused no standing wave problems in the harbor. NOTE: This file is large. Allow your browser several minutes to download the file.
|Rights:||Approved for public release; distribution is unlimited.|
|Appears in Collections:||Technical Report|
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|TR-HL-82-17.pdf||23.81 MB||Adobe PDF|