Navigating Nor'easters: UD students examine beach changes with drone, kayak
The recent Nor’easter that blew through the region is the type of storm that can have a serious impact on Delaware's coast. Last weekend, a pair of University of Delaware students were out on Broadkill Beach getting measurements needed to paint a more precise picture of just how much of an effect it had.
As Delaware Public Media’s Katie Peikes reports, it’s part of a project to map and understand parts of Delaware’s coast.
Delaware Natural Resources Police and Sussex County authorities responded to a call last Sunday afternoon about a kayak floating in the water with no one in it. As the officers prepared to drive to the scene, the call was withdrawn. They learned it was a self-driving kayak that had been programmed on a mission to map Broadkill Beach.
“When you see a kayak floating around without a person, it can cause an alarm,” said Tim Pilegard, a marine studies student with the University of Delaware, whose unmanned kayak was seen floating in the water. “So we had a concerned person see what looked like an unmanned kayak and assumed somebody had fallen overboard.”
Waves, higher water elevations and possible flooding could cause significant changes to the beach in a short period of time.
Along with oceanography student Stephanie Dohner, Pilegard was at Broadkill on Sunday deploying that kayak and a drone to measure the shape of the beach. They wanted to see if the Nor’easter from several days earlier affected the beach, and if so, by how much.
“When a Nor’easter is coming around and the winds are coming out of the northeast and just blowing across the Delaware bay, they’re creating, one, waves from the fetch - we say how far the wind can blow in open areas - it’s fetch,” said Dohner. “But then it’s also piling up the water on this side of the bay.”
Dohner said the combination of waves, higher water elevations and the fact that the area has the tendency to flood, could cause significant changes to the beach in a short period of time.
That’s where unmanned kayaks and drones come in.
“I have a radio telemetry linked to the kayak so I’m talking to it wirelessly,” Pilegard explained. “And I have the mission loaded onto the software here and I’m loading it onto the kayak right now.”
Pilegard said the kayak is pre-programmed on a mission to collect data points. While it is on that mission, it collects data measuring the depth of the ocean. It tries to pick the best way to go from point to point and navigates itself. The kayak requires minimal check-up as it drives itself back and forth along a fixed pathway.
The kayak is equipped with a fixed speed of sound that sends a ping of sound down to the bottom of the ocean, and it records the time the ping takes to hit the bottom and come back to it. This helps researchers calculate the distance of the water below the boat - the depth of the sea floor.
Meanwhile, Dohner’s drone, a fixed wing eBee she calls “bumble”, flew through the air taking photos of the beach. Dohner programmed the drone’s flight height, location, and by how much percent each photo would overlap.
UD students have been pursuing coastal mapping projects even before a boot camp in August brought them together to experiment with different technologies along the coast. Dohner said they try to gather data near the shore and from the ocean, including the height of the sea floor, the shape of the beach, dune vegetation and marsh vegetation.
“And we want to collect that data before and after storms as quickly as possible, within a few days before the storm hits and a few days after,” Dohner said.
Pilegard knew a storm was coming, so he went to collect data during the Friday before the storm and the Sunday after. Dohner, however, was at a conference and couldn’t collect data right before, so she is comparing her data from the drones to data from December.
Measuring beach data after a storm is important because coasts are constantly changing, Dohner said.
“Yet they’re one of most fun and actively sought after locations,” Dohner said. “We need to know how they’re changing, why they’re changing, what we do to the coast. That’s why we’re out here.”
Days after Sunday work on the beach, Dohner and Pilegard dug into their data. Pilegard said he was not able to tell which direction the sand was moving, but noted some sand was lost from the area he surveyed.
Dohner said she noticed an increased slope where the beach meets the water. She also noticed the wind and the waves basically took a bite out of the beach. This means sand was taken off the beach, but it may be under the water.
“Individual storms, even if they’re not historic level like Superstorm Sandy, are still affecting our beaches in ways we can see visually and that we can measure with instruments,” Dohner said, “and we should take that seriously whether it comes through data collection or planning projects for beaches.”
Dohner said they plan to survey the coast again this summer, unless another storm - and another opportunity to track coastal changes - surfaces before then.