Conservation Foundation Completes LiDar Drone Survey Of Coatue

For years, Nantucket’s conservation professionals have worried about the possibility of a breach at Coatue, which would radically change the ecosystem of Nantucket Harbor. Now, for the first time, the Nantucket Conservation Foundation has an accurate map of the barrier beach’s elevation, allowing the nonprofit to get a better idea of where the beach is vulnerable and how to protect it.

“Second Bend has shown clear signs of increasing vulnerability,” Nantucket Conservation Foundation coastal wetlands research ecologist Emily Junkins said. “Overwash events during storms and higher high tides have compromised the primary dune near the Harbor allowing water to enter the road and inundate the interior. This survey quantifies that erosion for the first time and lets us see how Second Bend fits into the broader risk profile of the property.”

Last spring, the Nantucket Conservation Foundation flew a drone over Coatue, taking highly detailed remote sensing images using a technology known as LiDAR, which were then stitched together to create an accurate map of the area’s topology.

“Coatue, the Haulover, and Great Point are among the most iconic and ecologically significant landscapes on Nantucket.” Nantucket Conservation Foundation president Cormac Collier said. “Their stability is directly tied to the health of the harbor and the island as a whole.”

Erosion and sea-level rise have been issues at Coatue, prompting the Nantucket Conservation Foundation to move its ranger shack further from the water. Driven by climate change, the erosion and sea-level rise pose serious environmental risks to Coatue.

Funded by a $70,000 grant from the Great Harbor Yacht Club Foundation, the map is by far the most detailed and consistent look at the beach’s elevation ever created. In the past, the Nantucket Conservation Foundation relied on manual measurements of representative parts of the beach. Now, they have a complete record of Coatue’s topology.

“The Great Harbor Yacht Club Foundation's support made this survey possible, and we're grateful for it,” Junkins said. “With this data, we can move from a general sense of where the risks are to a prioritized, site-specific plan for where intervention will have the greatest impact.”

Coatue is jointly stewarded by the Nantucket Conservation Foundation and the Trustees of the Reservation as part of the Coskata-Coatue Wildlife Refuge, and the survey was carried out as a joint project between the two organizations.

The survey itself was carried out with GZA GeoEnvironmental, Inc., a geotechnical and environmental engineering firm.