Waikiki Beach, Oahu, Hawaii: History of Its Transformation from a Natural to an Urban Shore

Waikiki, in Honolulu, Hawaii is a narrow beach that has been modified extensively. This history from a coastal engineering perspective is of the shore between Kewalo Basin and the Elks Club near Diamond Head. The beach and reef are exposed to waves from the south, with good surfing sites. A century ago, most of the shore was a narrow, thin ribbon of carbonate sand lying between wetlands, mudflats, duck ponds, fishponds, and a gently sloping fringing reef a few thousand feet wide. Not much sand was in the beach or the thin patches of sand on the reef. Several small streams flowed into the sea. The first en- croachment onto the beach with buildings and other works occurred in the 1880s and 1890s — a few homes, several bath- houses, and small hotels, some built partly on piles. Seawalls, groins, and several piers were constructed. The Natatorium was built from shore 200 feet onto the reef in 1927. The Ala Wai Canal and Ala Wai Yacht Harbor were also constructed. Of great importance was the removal of many truckloads of sand from the premises of Queen Lili'uokalani circa 1909, and the dredging of sand, coral rubble, and rock from the reef for fill of portions of the wetlands at Fort DeRussy in 1909. A dredge was used to clear a channel through the reef to the shore- line, and then parallel to the shore. In 1913, additional dredg- ing was done to permit a 69-ton coast artillery gun to be brought by barge to the reservation. Channels, basins, and ponds have been dredged in the reef for several purposes; they front about one-half of the shore. These have caused changes in wave and current action, and in the transport and deposition of sand and silt. Much of the sand now on the beach segments between Diamond Head and Ala Moana Beach Park has been brought from other locations in Hawaii for beach fill, or for construct- ing a beach by placing sand on top of a base made of crushed coral rock dredged from the nearshore. Also, sand was dredged in 2000 and in 2006 from small deposits on the reef, pumped to shore at Kuhio Beach, and distributed along the section of beach which is protected by a shore-parallel breakwater (crib wall), elevation about MLLW, and groins connected to shore. Since Duke Kahanamoku's comments in the 1930s, guidelines governing beach nourishment have been to preserve the break- ers for surfboarding, provide a sand blanket to cover the in- shore coral, and stabilize a dry beach for sunbathing. ABSTRACT