Inside a Georgia beach’s high-tech fight against erosion

This coverage is made possible thanks to a partnership between Grist and WabeAtlanta NPR station.

At low tide on the island of Tybee, in Georgia, the beach extends as largely as possible with the small waves that break away from the sand – you will have a long step if you want to immerse yourself. But these conditions are perfect for a team of researchers from the Oceanography Skiday Institute of the University of Georgia.

Every three months, at low tide, they put a miniature heliport near the foot of the dune and send their drone equipped with Lidar – a technology that points a laser down to the sand and use it to measure the elevation of the beach and the dunes. The team steals back and forth of the breakers to the other side of the dune and back until they have a complete and detailed map of the seven-mile beach of the island, about 400 acres.

“This is great precision, it is a high resolution,” said research technician Claudia Venherm, who heads this project. “I see each switch on the beach.”

This detailed information is crucial because Tybee is a barrier island, and the on the rise constantly gnaws at the sandy beach and the dunes which protect houses and businesses on the island as well as an extent of the continent of Georgia. Knowing exactly where the island is eroding and how dunes resist constant beats can help local leaders protect this coast.

“Tybee wants to keep his beach. He also wants to maintain, obviously, his dune. It is protection for them,” said Venherm. “We also give some of our data to the Corps of Engineers so that they know what’s going on and when they have to reconnect.”

Since the 1970s, the body of army engineers has helped maintain the beaches of the island of Tybee with a regular renovation: every seven years approximately, the dredging body of the sand from the ocean and deposits on the beach to replace the sand which was swept away. Skidaway team data will only help the body do this work more effectively. The Lidar is not new, and no more aerial coastal cartography. Several federal agencies monitor the coasts with Lidar, but these investigations are more generally interval for a single place, rather than a few months.

The last renovation ended in January 2020, and Venherm and his team set to work a few months later. This means that they have five years of data on the high resolution beach, recorded every three months and after major storms such as Hurricane Helene, creating a precise image of how the beach changes.

“I can calculate what the elevation of the dune is, as well as the quantity of volume lost or won from a previous survey,” said Venherm. “I can also calculate the time it will take until the beach is completely left, or how long it will take until the water reaches the dune system.”

The body regularly conducts renovation projects on the beaches throughout the east coast and uses a model to inform this work, said Alan Robertson, a consultant who leads the planning of the resilience of the city of Tybee. But he hopes that such granular evidence of specific changes can change where exactly sand is placed within the limits of this model. An area near the northern end of the island, for example, is a clear hotspot for erosion, so that the city can continue to concentrate the sand and north of this point so that it can travel south to fill erosion.

“We know exactly where the hot dots of erosion are. We know where there is an accretion,” he said, referring to the areas where the sand tends to accumulate. “”[We] Never this before.

Data can also shed light on the city’s decision -making because it provides a much clearer image of what happens to dunes and the beach over time after adding fresh sand. In the past, they have seen the most obvious erosion, but now they can compare how much the different methods of creating dunes and even the sources of sand are maintained. The vegetation which is essential for the maintenance of the dunes, for example, takes much better in the flirted sand of the ocean compared to the truck sand from the continent, said Robertson.

“There is an example of research and surveillance. I can actually make this statement,” he said. “I really know where you should get your sand if you can, and why. No one could have told you eight years ago. ”

This type of proven information is essential in resilience projects, which are often expensive and funded by agency subsidies that wish to confirm their money is well spent.

“Everything we do now about resilience, measure and surveillance has become a priority,” said Robertson. “We have been able during these years through declarations of proof of” look at what it is for you to be part of the project “.