Disappearing coasts: a smartphone and sel

Disappearing coasts: a smartphone and sel

Coast Protection

New mobile technology makes it possible to better monitor the Danish coastline, which is receding up to four meters a year in some places. This method, which has been tested by the University of Copenhagen, also allows citizen scientists to assist researchers and government agencies in monitoring coastal erosion and may provide us with a better understanding of erosion in the future.

A holiday home along the edge of a sandy cliff high above the North Sea is not a rare sight along the coast of northwest Jutland. Each year, between 0.5 and 4 meters of this coastline is eroded by storms and heavy ocean currents.

In the most serious cases, this leads to the destruction of buildings and endangerment of human life. Therefore, it is important for researchers, government agencies, and homeowners to track vulnerable coastlines.

Today, the most popular coastal monitoring technology publishes satellite data, which can only capture 2D observations. Gaining more detailed insights into coastal erosion requires relatively large and expensive instruments known as ground-based laser scanners. However, these tools are difficult to work with and not very popular.

Local monitoring can now be done using a basic setup like iPhone, selfie-stick, and app. Newer iPhones are equipped with the so-called LiDAR scanner, which is located on the back of the phone alongside the camera lenses.

“For technology manufacturers, the LiDAR scanner is being used to improve camera AF, but for me and my research team, it is a simple, inexpensive and less resource-intensive way to measure coastal erosion. In the future, this will allow more people to help monitor,” explains Ph.D. Gregor Lutzenberg from the Department of Earth Sciences and Natural Resource Management at the University of Copenhagen.

Citizen scientists can help with monitoring

LiDAR is an acronym for Light detection and range. The phone-based 3D scanner emits 576 laser pulses in all directions, making it possible to measure the depths, among other things, in a landscape.

According to Luetzenburg, the new survey method has great potential for more comprehensive coastal monitoring. This is especially true if those who live in high-risk areas can be motivated to participate in citizen science.

“It’s a bit like recording a phone video. So, if you’re someone who regularly walks your dog along one of these stretches of the disappearing coast, you obviously, along with other citizens around the country, can help researchers and government agencies with the important mission of in coastal surveillance,” says Gregor Lutzenberg, who has just returned from field research in Greenland.

While in Greenland, he developed a guide for geography students on how to use the LiDAR Scanner to measure rocky Arctic landscapes. According to Luetzenburg, something similar could be designed for citizen scientists.

However, if people want to help monitor the Danish coast, an IT platform will have to be created through which videos can be easily transmitted. The researcher says this shouldn’t be a huge challenge in our global digital society.

Gregor conducted a comprehensive test of the LiDAR method measuring 1,500 square meters from Rone Klint, about an hour’s drive south of Copenhagen. Photo: Kent Borksen, IGN / SCIENCE

Method tested in Rone Klint

Gregor Luetzenburg’s ongoing PhD project combines iPhone LiDAR scanner data with geological data, as well as knowledge about precipitation and winds, to learn more about the factors affecting coastlines.

He did a comprehensive test of the LiDAR method measuring 1,500 square meters from Rone Klint, about an hour’s drive south of Copenhagen.

“The soil in Ron Clint is sandy and was formed by glaciers during the last Ice Age, which makes it very eroded. A single storm can reshape the entire surface of a cliff. If you own farmland or dwelling just beyond the cliff edge, it is important to have an idea of ​​how long it will take. The sea erodes your possessions,” says Luetzenburg.

facts

  • Denmark’s western coast suffers from constant erosion. Movement of waves, winds, and currents causes constant erosion, while less sediment is carried toward the coast than away from it.
  • Storms generate severe erosion, as the impact of the waves washes sand away from the shoreline and coastal cliffs.
  • LiDAR is an acronym for Light detection and range. The 3D scanner emits 576 laser pulses in all directions, which makes it possible to measure the depths, among other things, in a landscape.
  • This technique is very useful for researchers and others to measure the amount of sand eroded from a cliff in the aftermath of a storm.
  • Today, the most popular coastal monitoring technology publishes satellite data, which can only capture 2D observations.
  • Getting a more detailed look at coastal erosion requires relatively large and expensive devices known as ground-based lasers. However, these tools are difficult to work with and not very popular.

Contact

Gregor Lutzenberg
PhD
Department of Earth Sciences and Natural Resource Management
University of Copenhagen
+45 35 33 53 88
gl@ign.ku.dk

Michael Skov Jensen
Journalist and Team Coordinator
College of Science
University of Copenhagen
+ 45 93 56 58 97
msj@science.ku.dk

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