Human impact on O‘ahu’s environment is a sticky issue: artificial constructs can both destroy and preserve its natural beauty, and it’s worth noting that some constructs wouldn’t become necessary except for human interference in the first place. Nowhere is the impact more obvious than on O’ahu’s beaches.
It’s no secret: beaches are the island’s top attractions and best commodities, for recreational, social, and cultural reasons. But in some locales where urban development has marched right up to the high tide mark, the beaches are in serious danger of disappearing, if they’re not gone already.
There are natural processes in Hawaii, like large swell events, seasonal currents, and storms with heavy rainfall, that move sand up and down the beach, offshore, and then back again. This natural and transient process is called coastal erosion and has been going on for centuries and will continue to shape the beaches until the island erodes back into the Pacific altogether.
In the meantime, recent human alteration of the shoreline has played a detrimental leading role in the disappearance of sand and entire beaches altogether. On O‘ahu, when the ocean shoreline encroaches within 20 feet of a structure, the property owner can be granted a variance that allows them to build a seawall to protect the property. Once the natural beach dune system is stripped away and replaced with a seawall, the beach has no way to store or replenish sand for periods of natural coastal erosion, leading to a permanent state of beach erosion. You’ll find this phenomenon in Kahala, Lanikai, and on other stretches of beach along the windward coast where dwellings have been built right up to sand. Where the shoreline is armored, the beaches have washed away.
Fortunately, in some cases, the damage done to O‘ahu’s environment by humans is reversible. Ka‘ena Point has long been home to a variety of Hawaii’s wildlife, a chorus of flora and fauna on land and in the sea. In years past, human impact took a devastating toll on the fragile ecosystem: off-road vehicles tore up the dunes, destroying native vegetation and disturbing seabird nesting sites, and feral cats, dogs, rats, and mongooses decimated seabird populations, namely the wedge-tailed shearwater and Laysan albatross that nest in the dunes, by eating eggs and killing juvenile birds.
Today, because of the Ka‘ena Point Natural Area Reserve Ecosystem Restoration Project, Ka‘ena Point is a natural restoration success story. Integral to the return of native plant species, native insects, and nesting seabirds is the predator-proof fence. Completed in 2011, the 6.5-foot-high fence uses a fine mesh technology to protect the 59-acre reserve from predation by invasive species. Spanning 700 yards and following an old railroad track roadbed around the point, the fence is also buried underground with the ability to keep two-day-old mice from entering. A double-gated entry system ensures unwanted pests cannot sneak in, as only one door can open at a time. The fence is unobtrusive and colored to blend in with the natural vegetation and geography. Since its completion, native vegetation has returned and nesting seabird populations are steadily increasing.