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Sand dunes can "communicate" with each other


Obviously, sand dunes cannot talk to each other in the sense that we put in this concept. However, dunes can influence neighbors, as if communicating their physical position to these physical structures. This statement was made by a team of scientists from the University of Cambridge, which experimentally established that as the sand dunes move, they interact and repel their neighbors along the stream.

Try to imagine a sand dune. She will not be alone? There are still dunes around it - tons of fantastically located sand. It is hard to imagine a lone sand dune. On land or under water, sand dunes are usually located in large groups. But when migrating over long distances, these structures unexpectedly change their growth rate, and ultimately turn out to be evenly distributed, which leads to thoughts about how these sand mounds can “communicate”.

If you play a little words, they could be called "social beings." A particular irony is the fact that even when the dune is surrounded by a large number of "neighbors", it may require personal space. And the sandy “community” provides this space.

Sand Theories


There are different theories of dune interaction. The most popular were two of them:

  • The first assumes that dunes of different sizes will collide and continue to collide until they form one giant dune. I note that this phenomenon has not yet been observed in nature.
  • The second is that the dunes can collide and exchange mass, like billiard balls bouncing from each other until they become the same size and move at the same speed. But this version does not yet have direct evidence.

Scientists from the University of Cambridge conducted a study that provides a new explanation for the movement of the dunes. A report on its results was published in 2020 in the journal Physical Review Letters ( text and models ). This is not just a theoretical study of the next British scientists. Migration of dunes leads to desertification of vast territories, and therefore is a growing threat, especially in conditions of global warming. These sand structures can threaten shipping channels and road infrastructure. In Africa and the USA, for example, a sandy road is not such a rare occurrence. That is why not one or two research groups spend their time studying dunes, model their behavior and try to understand the processes of education and migration.

New experiment - new answers



The two theories that I talked about earlier do not seem reliable. It is known that small sand dunes move faster, and large ones slower (here's a short video on the topic). Accordingly, the same dunes will move at the same speed. But recent experiments show that this is not always the case. For example, two sand dunes of the same volume and shape can accelerate or decelerate in order to move farther apart without exchanging a significant part of their mass during migration.

The Cambridge laboratory has developed an experimental setup that allows you to monitor the long-term behavior of the dunes. In general, there were several such installations. In the latter, scientists created an artificial water channel with walls raised above the surrounding area (that is, it was not just a ditch). The circular stream was supposed to allow researchers to observe the interaction between the dunes.

During the experiment, two identical dunes were formed in the installation with water, and scientists expected identical motion from them. However, at first the front dune moved faster, slowing down from time to time. Gradually, the dunes moved apart until they formed equilibrium on the opposite sides of the circular stream. Their speeds became very similar, and they remained on opposite sides of the circle.

It turned out that the front dune creates turbulence that affects the back dune. In general, the shape of the stream behind the front dune is similar to the trail left by the boat. And it affects the properties of the dune following it.

Curiously, the researchers initially placed several dunes in the tank only to speed up data collection. Therefore, the interaction of sand structures with each other was a pleasant surprise for them.

What's next?


Using these randomly obtained data in general, we can proceed to the next step: studying the development of dunes in other types of environment. For example, in desert conditions. In addition, new information will be used to decrypt the “dune language”. For this, satellite images will be further analyzed. Perhaps in the future, these studies will help protect important objects for humans from being absorbed by migratory sand structures.

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