Researchers use drones to understand how waves are shifting Waikiki beach

HONOLULU (HawaiiNewsNow) – On Oahu’s south shore, researchers are using consumer drones to learn more about how sand moves along the beach.

Two studies recently completed by University of Hawaii researchers aim to provide policy makers, state agencies and even businesses along the beach with better information and better practices when it comes to managing and preserving the beach.

One study, based on weekly drone surveys between 2018 to 2020, found the sand appears to move from one end of the beach to the other — not to and from offshore, as previously believed.

Scientists took overlapping images and recreated the beach into a 3D model from which they were able to measure things like the beach volume and how the sand moves.

By comparing this movement to environmental conditions like trade winds, south swell or a storm, they’re able to better pinpoint what is moving the sand on a week to week basis.

“What we found was that quite often, the sand is actually moving along the shore. So that means essentially just that the sand is moving from one section of the beach wedge eroded. And on to the opposite section of the beach, where it often accretes are built onto the beach,” said Anna Mikkelsen, a geospatial analyst with the Climate Resilience Collaborative, where this research is published.

Another part of this research, a study conducted CRC Geospatial Analyst Kristian McDonald, surveyed the beach over a much shorter period: April through November of 2018.

If that sounds like a unique and memorable time period for Hawaii, it is — it was an active hurricane season for the islands.

Waikiki saw huge swells that summer from Hurricanes Hector, Lane and Walaka.

McDonald says hurricane activity of 2018 generally increased the surface area and volume of Waikiki beach.

“We were a bit surprised. I think people tend to associate waves with beach erosion and we were kind of surprised to see that the southerly swell has actually worked to build the beach in Waikiki,” said McDonald who adds that climate change and sea level rise will also change things for the southshore.

“I think big picture wise, sea level rise will definitely contribute to the erosion of our beaches. I think as sea level rises, the beach naturally wants to move inland and will call upon say like the dune system to replenish itself.”

Researches continue to monitor Oahu’s coastline and are even comparing these images to satellite imagery taken in the 90′s to get a broader perspective.

To more on the research, click here.

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