Faleasao Harbor, American Samoa : Investigation of modifications for improving navigation
Demirbilek, Zeki.; Lin, Lihwa.; Nwogu, Okey G.; Goo, Justin A.; Smith, Thomas D.
This report describes details of a numerical modeling study conducted to evaluate impacts of infrastructure modifications for improving navigation in Faleasao Harbor in American Samoa. The existing harbor and three proposed infrastructure modifications (Alternatives) were investigated. This small, federally constructed, shallow-draft harbor is located on the northwest coast of Tau Island, the largest island in the American Samoa islands chain. Navigation in the harbor is affected by waves passing over reefs located to the north and northwest of the harbor. Swells from the north and northwest undergo shoaling and breaking on the reefs, which generate unfavorable conditions to boats entering and leaving the harbor. The shallower harbor entrance area is flanked on the west by a rocky natural headland and an unraveling detached west breakwater that is now a disconnected spur. A jetty along the east side of the navigation channel extends a short distance northeast from the boat launching ramp. These structures protect the harbor interior from waves and currents and reduce sedimentation. Smaller vessels access the harbor through a narrow navigation channel approximately 300 m long, 40 m wide, and 4 m deep. The south end of the channel connects to a small turning/mooring basin where vessels can turn or moor at the dock. Wave processes in both exterior and interior areas of the harbor were investigated in this scoping-level study to determine benefits and consequences of three proposed infrastructure modifications for improving navigation in the harbor. These include deepening of the navigation channel and turning basin and adding structures to the tip of west peninsula. Modeling results indicated that the modifications reduced wave energy in the harbor and improved navigation in the channel, turning basin, and dock areas, thereby ensuring access by larger vessels to the harbor. Under typical weather conditions with the proposed modifications, wave estimates obtained indicated that the American Samoa Government’s (ASG) largest vessel MV Sili would be able to access the harbor. Preliminary wave estimates for design and repair of infrastructures were also provided.
Coastal and Hydraulics Laboratory (U.S.)Engineer Research and Development Center (U.S.)
Navigation; Small-boat harbor; Wave modeling for planning and operations; Waves; Wave models; Harbor access/usability; Harbors; CMS-Wave; BOUSS-2D model; Numerical models; Mathematical models; Structural design; Faleasao Harbor; American Samoa
Technical Report (Engineer Research and Development Center (U.S.)) ; no. ERDC/CHL TR-15-15
Approved for public release; distribution is unlimited.