Coastal Erosion

The long dark reef that is located towards the center of the photo was once a part of the shoreline that children in Waianae used to jump off of into the water.

Residents living on the coastline of Hawai‘i are most at risk with coastal erosion due to tropical depressions and rising sea-levels, according to studies conducted by multiple organizations. 

In late May, the National Oceanic and Atmospheric Administration predicted above-normal rainfall through the summer for Hawai‘i Island and Maui County, and below normal for O‘ahu and Kaua‘i.

In addition, NOAA anticipates five to eight tropical cyclones for the Central Pacific hurricane basin, which includes both large storms and hurricanes. This outlook was to give a general guide to the Pacific area and does not necessarily mean it will affect Hawai‘i.

According to the United States Geological Survey Coastal and Marine Geology Program, “Of the most severe catastrophes in the Nation’s history, hurricanes account for two-thirds of the insured property losses.”

Living in Hawai‘i comes with many expenses, one being that residents are more at risk from coastal hazards which can damage property and cost thousands of dollars. High wind storms and the waves they generate are also of concern to coastal land managers and owners.

Coastal Erosion and beach loss in Hawai‘i

Coastal erosion has continued to be a major issue in Hawai‘i. It is often defined as the displacement of land or loss of coastlines due to factors such as currents, waves and storms.

“Dramatic examples of coastal erosion, such as houses and roads falling into the sea, are rare in Hawaii, but the impact of erosion is still very serious,” according to a USGS Hawaii Beach Monitoring Program report.

According to a study by Jessi Kershner, a senior scientist at EcoAdapt, “It is estimated that Oahu has lost 25 percent of its beaches from seawall construction resulting in beach erosion, while 72% of the beaches in Kauai are chronically eroding.”

While the state of Hawai‘i has some restrictions on shoreline development, many counties have chosen to establish more conscientious guidelines based on the rate of erosion over a longer period of time.

“Usually it is our shoreline that receives a hurricane’s most immediate and immense blow,” Charles “Chip” Fletcher, University of Hawai‘i’s Associate Dean for the School of Ocean and Earth Science and Technology, said. “Sitting in the crosshairs of an approaching storm, the shoreline endures the first and most severe pummeling from the wind, waves, and floods.”

Hurricane impacts in Hawai‘i

According to SOEST, even a relatively weak tropical storm can potentially result in property damage if it makes a direct hit.

Hurricanes and tropical storms cause sea levels to rise, known as a storm surge, and can cause extensive shoreline erosion and the loss of property or even life.

“Coastal erosion compromises any buffering effect that beaches and wetlands may have because high waves and storm surge can strip a beach of its sand and undermine homes, roadways, and businesses,” Fletcher said. 

Safety and mitigating hurricane damage

According to Fletcher, the simplest way to avoid these hazards is to avoid developing on the shorelines.

“If we stopped putting communities on the edge of the ocean, we would greatly reduce the suffering, loss of life, and enormous damage caused by hurricanes and other types of coastal hazards,” Fletcher said.

O‘ahu resident and staff member at UH Mānoa Heather DeWoody lives on the Windward coast in Waimanalo and shared her hurricane preparations in an email interview.

“Since our 2019 Central Pacific Hurricane Season began on June 1, I have been fortifying my hurricane prep kit. After the last hurricane we experienced here in Hawaii I stocked up on bottled water, purchased a first aid kit, a head lamp, extra batteries, a portable battery charger, hygiene items, cash in small bills and photocopies of my important documents,” DeWoody said. “When a warning is broadcast, I always fill my gas tank up. I also stock up on non-perishable foods.”

DeWoody is an educational researcher for the College of Education, and a doctoral student in the Educational Foundations department. 

“Luckily, the owner of the home I live in now has not had to make any repairs to the house due to coastal erosion,” DeWoody said. “I believe this is because the home is far enough back from the coastline and buffered by a grassy area that this has not been an issue, whereas homes on other parts of the islands may well face this issue.”

Not being prepared for hurricanes and future coastal erosion can result in a total loss of Hawai‘i’s beaches and of numerous coastal properties and significant damages to waterfront roads and other coastal infrastructure.

The National Weather Service provides important guidance to emergency managers by issuing hurricane advisories. NOAA suggests early evacuation to higher ground for people most susceptible to the destructive forces of a storm surge.

Homeowners in Hawai‘i can help themselves by making their properties less susceptible to damage by hurricanes and windstorms.