Grant to support development of West Maui wave forecast system

Erosion has forced Kahana condominium properties to put up sandbag barriers. A wave run-up forecast tool is being developed by the University of Hawaii Pacific Islands Ocean Observing System with a half-million dollar federal grant. This will give residents about a six-day heads-up for a coming big wave/shoreline run-up event. -- University of Hawaii-Manoa photo

A wave run-up forecast and notification system for West Maui, where residents can get a six-day “heads-up” of possible large wave and flooding events along specific sections of shoreline, will be developed by a University of Hawaii ocean observation program with a $500,000 federal grant.

“This is very site-specific . . . and it will increase overall preparedness for the public, county, road crews, emergency managers,” said Fiona Langenberger, communications and program coordinator for the UH-Manoa Pacific Islands Ocean Observing System, which received the National Oceanic and Atmospheric Administration Regional Coastal Resilience Grant.

In addition to developing long- and short-term forecast models, PacIOOS will develop ocean inundation planning scenarios based on rising sea levels and increasing wave energy, according to the UH news release Friday announcing the grant. This will be a tool for communities and government entities when developing along West Maui shorelines.

The three-year project is expected to begin in October.

This project comes on the heels of recent king tides events, where peak high tides have coincided with unusually high sea levels. While no major damage has been reported, waves have splashed seawater onto passing cars on segments of Honoapiilani Highway, and a monk seal meandered to the shoulder of the highway.

Waves run up onto Honoapiilani Highway during a recent king tides event. The highest tides of the year coupled with unusually high sea levels have undermined sections of the highway, forcing the state to take fortification measures unpopular with some residents. The University of Hawaii Pacific Islands Ocean Observing System is developing a wave run-up tool for short-term notifications and long-term planning. -- University of Hawaii-Manoa photo

These king tides events are expected to increase in number and duration, according to the UH news release. The high water levels and large wave swells can result in coastal erosion, damage to infrastructure and properties, and sedimentation that decreases coastal water quality.

Rising sea levels and erosion have led to the ocean splashing onto lanai at condos on the west side. Homeowner associations have had to seek permits for expensive projects to fortify shorelines fronting their buildings to prevent them from falling into the ocean.

“We are affected by chronic shoreline erosion in West Maui,” said Tara Owens, a project co-investigator and UH Sea Grant College Program coastal processes extension agent. “Some of the properties that are built close to the shoreline are literally on the brink of falling into the ocean.”

Honoapiilani Highway, the main artery between West Maui and the rest of the island, is also a “major concern,” said Owens.

“These roughly 21 miles of coastline are extremely important for Maui’s economy, local businesses, homeowners and visitors, and yet they are extremely vulnerable to the impacts of rising sea levels and wave inundation,” she said.

To develop the real-time, site-specific wave run-up forecast for the west side, PacIOOS will deploy pressure gauges and current meters in three spots along the coastline in depths of 6¢ feet to about 60 feet. The gauges and meters will be put in the ocean for three-to-four-month periods during winter and summer, said Langenberger.

This data will be combined with wave information from PacIOOS buoys.

“With the instrumentation, we will gain a very detailed time series of the sea level, currents and waves in the West Maui area,” she said.

The models and forecasts, which are meant to be area specific because conditions differ along the coastline, will be divided into about a dozen segments based on topography and other features, said Langenberger.

“West Maui is exposed to both large north and south swells that wrap into the coast in odd ways due to the ancient offshore reef topographies,” said project co-investigator Douglas Luther, a professor with the Department of Oceanography at UH-Manoa School of Ocean and Earth Science and Technology. “While certain parts of the shoreline might not see any impacts, other sections can be appreciably flooded.”

The model will use offshore and shoreline wave development characteristics to determine the “varying levels of vulnerability along the coast during each swell event,” he said.

The project will employ citizen scientists to document its models and forecasts.

“If the model predicts a certain amount of wave run-up for a specific segment, what exactly does it look like on the shore?” Langenberger said. “We will work with citizen scientists to help document certain events with photographic surveys.”

Short-term forecasts will provide “a six-day heads-up on how likely it is that wave run-up will occur” along a specific shoreline,” said Langenberger. Residents may prepare for getting splashed on Honoapiilani Highway or closing patio doors to prevent the ocean from splashing into condos.

The forecasts will be posted, when developed, on, she said.

For long-term planning scenarios, scientists will play with environmental factors in the model, such as increasing sea level by a certain amount, and observe the projected effects. These scenarios could be useful for implementation of erosion mitigation and beach restorations projects and land use and infrastructure planning and permitting, Langenberger said.

“We will work closely with coastal managers, emergency managers, property owners and local residents on Maui and around the state to ensure that data and tools are easy to understand and suitable for short- and long-term decision-making,” said principal investigator Melissa Iwamoto, PacIOOS director. “The goal is to better understand site-specific risks and vulnerabilities so that such stakeholders can integrate the information into community planning, policymaking and hazard-related ordinances.”

Project partners include UH School of Ocean and Earth Science and Technology, Hawaii Sea Grant, state Department of Land and Natural Resources and the County of Maui.

* Lee Imada can be reached at