Assessment of Modifications for Improving Navigation at Hilo Harbor, Hawaii

Abstract : Numerical wave and flow modeling studies were conducted to evaluate modifications to improve navigation at Hilo Harbor, HI. Analysis of field data, hydrographic surveys, and numerical and ship simulation modeling calculations are described in this report. The existing mooring and turning basin area adjacent to the Federal channel cannot safely accommodate the size of vessels presently using the harbor. A second issue affecting navigation in Hilo Harbor is the surge problem, which occurs mostly during winter swells when ships are in the berthing areas, describing a pulling away of ship movement from the piers, a form of long-period wave phenomenon commonly known as harbor oscillation. CMS-Wave and BOUSS-2D models were used to investigate potential Alternatives to address navigation conditions in Hilo Harbor, with field data from 2007 and 201314 for calibration of the numerical models. Alternatives considered included modifying the breakwater, incorporating structures in the interior harbor, and deepening and expanding the mooring basin to provide more space for safe mooring and maneuvering of ships. Results of this study indicated that the addition of a spur to the western-most tip of breakwater would provide the greatest reduction in wave and currents in the harbor.