Prior to the construction of Kīkīaola Small Boat Harbor, the shoreline was relatively straight with a long, wide beach extending approximately 2.7 miles from Waimea River to Olomano Point in Kekaha. A strong westward littoral drift moves sand along the beach in shallow water. After the construction of the harbor the beach up drift of the harbor accreted at an average rate of 2.4 feet per year, while the down drift beach eroded at an average rate of 2.1 feet per year. It is apparent that the interruption of the natural sand movement caused by harbor structures resulted in beach modifications and also contributed to the shoaling of the harbor entrance.
Oceanit analyzed options for a long-term sand bypassing program to reduce the rate of siltation at the Kīkīaola Harbor entrance and reduce the severe erosion of the down drift beach. The program involved an initial transport of 60,000 to 80,000 cubic yards of sand from the beach east (up drift) of Kīkīaola Harbor to nourish the beach west (down drift) of the harbor. In addition, an annual sand bypassing scheme to nourish the down drift beach with about 5,000 cubic yards of sand was incorporated into the program. The project also included erosion damage repair to the west breakwater root section. In response to harbor users’ complaints about high wave action within the harbor, a wave penetration study was conducted over a 12-month period to investigate the wave conditions within the harbor.