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Title: Wave and current conditions for various modifications of Kewalo Basin, Honolulu, Oahu, Hawaii : hydraulic model investigation
Authors: United States. Army. Corps of Engineers. Pacific Ocean Division.
Giles, Michael L.
Keywords: Hydraulic models
Kewalo Basin
Water currents
Water wave experiments
Water waves
Ocean currents
Publisher: Hydraulics Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Technical report (U.S. Army Engineer Waterways Experiment Station) ; H-75-15.
Description: Technical Report
Abstract: A 1:75-scale undistorted hydraulic model of Kewalo Basin, Oahu, Hawaii, and sufficient offshore area to permit generation of the required test waves was used to develop and test several plans of improvement proposed to eliminate: (a.) crosscurrents in the entrance channel, (b.) the presence of peaking and breaking waves in the entrance channel, and (c.) undesirable wave action in the basin. Improvement plans consisted of a proposed wave absorber along the channel sides, various jetty plans, removal of the channel, and various combinations of the above. A 50-ft-long wave machine and an electrical wave height measuring and recording apparatus were used in the model. Tests were conducted with existing conditions installed and the results were compared with those for various improvement plans. It was concluded from the test results that : (1.) Strong wave- induced crosscurrents entered the existing harbor channel for several hundred feet seaward of the existing jetty; and for some wave conditions, crosscurrents entered both sides of the channel and an eddy was formed. (2.) Peaking and breaking waves occurred in the existing channel for incident wave heights of 8 ft or greater (at the wave generator located at a depth of -60 ft mllw) due to strong seaward-flowing currents and the channel shoal. (3.) Wave heights up to 3.4 ft were measured in the existing basin, but piers in the basin generally prevented the formation of well-developed standing waves . (4.) Addition of a wave absorber along the sides of the entrance channel (plan 2) was the most effective improvement plan in reducing wave heights in the basin (an average of about 13 percent and maximum wave heights were reduced from 3.4 to 1.9 ft), but this plan had little effect on current conditions. (5.) A 150-ft jetty extending due south from the end of the existing jetty with a +2.0-ft crown elevation (plan 3D) was the best of the 150- ft jetty plans tested. This plan increased wave heights in the basin slightly (about 9 percent), and wave heights exceeded 2-ft four times. Channel currents in the area immediately adjacent to the jetty were significantly reduced. (6.) Currents in the outer portion of the channel were relatively unaffected by a 150- ft jetty extension (in some cases, an increase in velocity was noted just seaward of this jetty). (7.) Removal of the channel shoal (plan 8) tended to slightly increase basin wave heights (about 2 percent) by allowing more energy to enter the harbor, and wave heights exceeded 2 ft three times. (8.) The shoal removal changed wave-breaking characteristics slightly and reduced eddy currents for some test waves. (9.) Combinations of wave absorber and 150-ft jetty (plan 4), wave absorber and shoal removal (plan 7), and wave absorber, 150-ft jetty, and shoal removal (plan 5) effected slight overall reductions in wave heights (about 6, 10, and 5 percent, respectively). Wave heights in the basin did not exceed 2-ft for these plans. (10.) A combination of 150-ft jetty extension and channel shoal removal (plan 6) increased overall wave heights significantly (about 18 percent), and wave heights in the basin exceeded 2 ft seven times. (11.) The 500- and 900-ft jetty extensions (with channel wave absorber) tended to reduce basin wave heights, and channel eddy currents were eliminated . (12.) Current magnitudes were not reduced significantly for either a 500- or 900-ft jetty extension, but currents were shifted seaward (out of the entrance channel), thus providing better navigation conditions. (13.) Of all plans tested, only those involving the originally proposed wave absorber (plans 2, 4, 5, and 7) did not produce wave heights in excess of 2 ft inside the harbor basin.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Technical Report

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