As sea level rises, state considers the perils and opportunities of ‘managed retreat’

As sea level rise threatens coastal communities in Hawaii, state struggles to find solutions

HONOLULU (HawaiiNewsNow) - Accelerating sea level rise brought on by climate change poses significant challenges to Hawaii’s shorelines, according to geologists who have been studying the state’s coastlines for decades.

The state recently commissioned a project to assess the feasibility and implication of managed retreat by looking at how other regions have successfully moved from coastlines.

And the biggest takeaway: Managed retreat is a difficult but necessary option to consider.

“Managed retreat is the idea that we move our communities out of the way because sea level is rising,” said University of Hawaii earth sciences Professor Chip Fletcher.

Hawaii’s shorelines are unique environments characterized by a number of natural hazards, including sea level rise, tsunami, storm surge, high winds and coastal erosion.

Experts all agree that building on eroding coasts increases vulnerability to these hazards, but finding a solution that everyone agrees on is much more challenging, especially when you start talking about managed retreat.

The concept of managed retreat is simple, yet making it happen is anything but.

Managed retreat is one of three main adaptation strategies to sea level rise and other coastal hazards. The other two are accommodation and protection.

According to coastal geologists, managed retreat essentially means shifting development inland from the coast either through the physical movement of structures or through legislation or policy that changes the restrictions and management of Hawaii’s shorelines.

Accommodation involves adapting existing structures and systems to allow them to better withstand changing conditions, like elevating a structure to hold up to wave inundation.

Protection efforts include both hard and soft solutions.

An example of a hard method is the construction of a seawall, while a soft method is considered beach replenishment or installation of something similar to the sand burritos that have popped up across Oahu’s North Shore.

Managed retreat is much more individualized approach that takes into consideration the coastline’s current conditions and existing hazards or impending threats. In some situations it could mean not only physically relocating existing buildings or shifting the placement of infrastructure, but also creating new regulations that restrict future development of vulnerable areas.

Ultimately, what the Office of Planning Coastal Zone Management Program determined in its report was that it is “currently not possible to develop a step-by-step plan to implement managed retreat for areas in Hawaii threatened by sea level rise and/or other coastal hazards given the various unknowns and competing priorities identified throughout the course of the assessment."

For example: protecting individual land owner rights versus access for the greater community.

Experts and state officials say they will continue researching the best possible solutions to ensure the Hawaii’s most prized and truly priceless natural resources remain protected for future generations.

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