An undistorted-scale hydraulic model study was conducted to provide input for design optimization of a rubble-mound jetty system proposed for Oregon Inlet, North Carolina. Two-dimensional (trunk) tests consisted of (a) developing stable stone and dolos sections (base designs) for a depth-limited breaking wave of 15 sec, 13.6 ft at a design swl of +5.5 ft; (b) subjecting the stable base designs obtained at the +5.5 ft swl to storm-surge hydrographs with peak levels of +6.5, +7.5, +8.5, +9.5, +10,5. and +11.5 ft NGVD and obtaining damage as a function of swl; (c) redesigning the armoring schemes for stable sections of +7.5 ft swl with a depth-limited breaking wave of 15 sec, 15.5 ft and subjecting these plans to storm-surge hydrographs of +8.5, +9.5, +10.5, and +11.5 ft NGVD and again determining damage as a function of swl; and (d) redesigning both the stone and dolos sections for stability at an swl of +9.5 ft with a depth-limited breaking wave of 15 sec, 17.2 ft. Three-dimensional tests were conducted to determine stable stone and dolos head sections for 15-sec, 17.6 ft waves at angles of wave attack equal to 0, 22.5, 45, 67.5, and 90 deg.

A three-dimensional, physical, hydraulic model investigation was performed to establish a stable jetty design for use in the proposed rehabilitation of the north jetty at Yaquina Bay, Oregon. The study was conducted at a geometrically undistorted linear scale of 1:45, model to prototype. Undirectional, spectral test waves were generated from three directions. Wave conditions were selected based on six hindcasted storms which covered the range of historical and probable worst wave conditions. Tests were conducted at still-water levels of 0.0 ft and +10.0 ft mean lower low water. The seaward end of the north jetty has undergone rapid deterioration since the previous 1977-1978 rehabilitation. The loss of approximately 400 ft of the jetty has resulted in increased deposition of littoral material in the entrance channel and more severe wave conditions at the mouth. Three mean amorstone weights (16, 23, and 29 tons) were used in the rehabilitation plan tested. This plan would restore the jetty to its original length and would utilize the 'placed-stone' construction technique. The model tests indicated that the recommended armor-stone weights were adequate and that the plan to employ 'placed-stone' construction of the jetty on existing deteriorated jetty stone was acceptable. Additional tests were performed with monochromatic wave conditions in an effort to compare wave heights measured in the physical model with wave heights predicted in an earlier study by the numerical model, RCPWAVE. A discussion of those test results is included.