Report examines shoreline changes, drawbacks of standard setback requirements

  • Courtesy photo Hurricane Lane, which dropped record amounts of rain on the Big Island in 2018, led to mudslides and other impacts along the Hamakua coast.

  • Courtesy Ryan McClymont/U.S. Geological Survey Hawaii County planner Bethany Morrison walks along the Ka'u coast during a University of Hawaii at Hilo research project that looked at coastal erosion on the Big Island, the results of which are helping shape county planning policies.

  • A drone photograph of cliff erosion was taken during a research project looking at Big Island coastal erosion. (Courtesy Photo)

Research on the Big Island’s coastal erosion, led by a University of Hawaii at Hilo graduate student, is being used to shape county planning policies.

Bethany Morrison, a planner with the county Planning Department, said the project was initiated because the county has a “very standard” shoreline setback requirement, regardless of the land type or climate-related changes that might be happening.

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Hawaii County is the only county in the state that hasn’t done research to understand the island’s shoreline changes, she said, but it’s something the county has been working towards for “quite a while.”

“This project was a really good opportunity for collaboration between research and applied management, so that we were able to get a product that made sense and helped build the research capacity of (the university),” Morrison said.

The two-year research project, which lasted from August 2016-May 2018, was funded by UH-Hilo’s Manager Climate Corps, a program of the Pacific Islands Climate Adaptation Science Center — itself a collaboration between the U.S. Department of the Interior and a consortium hosted by UH-Hilo, University of Hawaii at Manoa and University of Guam.

The study, led by UH-Hilo graduate student Rose Hart, evaluated shoreline erosion in three areas of Hawaii Island — Kapoho, Honolii and Hapuna Beach — by comparing historic photographs, new drone imagery and topographic surveys.

Data was then combined with projected sea level rises and other data to estimate further coastline impacts.

A case study on the research, titled “Reality Check: Collaborative Research Contributes to Real-Life Policy Decisions,” was recently published on the U.S Climate Resilience Toolkit website.

According to the case study — co-authored by Scott Laursen, a program specialist with the PICASC who coordinates the MCC program, and Morrison — UH-Hilo staff met with county planners, including Morrison, in 2016, who expressed the need for research that would support a “more comprehensive and effective coastal development setback policy.”

Despite the island’s differing shoreline geology, the county’s initial general plan only required a development setback distance of 40 feet from shorelines across the entire island.

“This largely arbitrary line did not account for different uses of the land, nor the constantly shifting environments distinct to each type of shoreline,” the case study reads. “Ultimately, it left some communities exposed to coastal hazards. The blanket policy applied over the entire island simply didn’t fit with the reality of the coast’s wide-ranging responses to the increasing effects of climate change.”

Laursen said the national climate adaptation centers were developed to help cultural and natural resource managers adapt to the impacts of climate change.

When he began his work with MCC in 2015, Laursen said he made his way around the Big Island interviewing various natural resource managers to find long-standing relationships and professional partnerships within the community because humans, as a species, “have always adapted through communities and cultures.”

The goal was to not build new relationships, but to find existing ones and support those through collaborative research, he said.

“To me, individually, it really helps to show the power of local relationships and how important it is to recognize that and build science with that understanding and actually within those local relationships to make the research products more useful on the ground, beyond a publication in academic journals,” Laursen said of the research.

According to the case study, the study findings were presented to the county Planning Department in May 2018, and suggestions were offered on how the county could use the data to create “place-based set backs.”

Morrison said the research is included in the draft update of the general plan, Hawaii County’s long-range planning guide, which calls for site-specific setback requirements.

The county is already looking to expand upon that initial research.

According to Morrison, there is a grant application into FEMA, and agreement with the state Coastal Zone Management program to “do the site work to be able to establish research-based shoreline setback.”

The new study would evaluate different shoreline types for the entire island to understand what changes might be coming and use that information to establish shoreline policies.

The U.S. Climate Resilience Toolkit is a website that aims to improve people’s ability to understand and manage climate-related risks and opportunities.

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The case study was also published on the Pacific Islands Regional Climate Assessment website.

Email Stephanie Salmons at ssalmons@hawaiitribune-herald.com.

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