Beach Erosion at Waimea Bay, Oahu, Hawaii

Abstract

Waimea Beach on the island of Oahu, Hawaii, is a popular recreation area, which is presently endangered by severe erosion. The extent of shoreline erosion has been determined from comparison of an 1884 survey map with aerial photographs from the period 1928-1975, and from measurements of the changes in the vegetation line during that time. The Waimea section of Oahu's shoreline has receded about 200 ft in this 47-yr period. This erosion is caused primarily by storms that move the beach sand into deeper waters from which it cannot return to the beach and the lack of supply of new sand to the beach. Sand mining and abrasion also have contributed to the retreat of the shoreline. Continued periodic measurements and aerial surveys would be valuable in tracking the regression of the shoreline and useful for planning the future of public facilities located in Waimea Bay.