Dunes: What are they, how they form, types and importance

The dunes are great accumulations of sand formed and modeled by the action of the windwhich can cover hundreds of thousands of square kilometers. Those that cover large surfaces are known as Ergs. There are different environments with the presence of dunes such as deserts, coastlines and coastal plains. Dunes are very dynamic systems, with high vulnerability, which is why they are of great interest.

The initial sand source to form the dunes is the deposited on the beaches Thanks to the water currents of the ocean, or lakes and rivers in the case of inner dunes. When the beach sand is exposed to the air for a certain time, It dries and is susceptible to being transferred by the windstarting the formation of coastal dunes. Although there are many sizes and shapes, they are all generated through the same process by the action of the wind. The factors that influence the formation of dunes are:

• The contribution of sediments.
• The size of the sediments.
• The wind speed.
• The presence of obstacles.

But how do these factors interact in the formation of these ecosystems?

1. Once the sediments have been provided, the formation of a dune begins when wind speed is enough To lift the grains of sand. When the wind blows, the grains move and the higher the wind speed, the greater the distance at which the grains of sand travel.
2. Once raised, the clouds of grains of sand will travel in the same direction as the wind, until it loses speed and the grains are deposited. The Presence of obstacles They will modify the wind speed. Therefore, a dune begins to form when the wind meets an obstacle. For example, a plant, a rock or a fallen trunk.
3. As this happens, the sand is deposited until a mound of sand is formed around the obstacle. This mound represents an even greater obstacle to the wind, accumulating more and more sand. Plants constitute the most effective obstacle, since they are able to grow as the sand accumulates. The height of the vegetation plays a very important role in the advance of the dunes, since the higher the wind speed will be the wind speed. In addition, the sand movement is affected by the amount of plants and the surface they cover.

Exist coastal dunes and interior dunes. The coastal dunes are found on the coasts, and the interior dunes are mainly in the deserts. Both types can be large and share characteristics such as nutrient shortages and water, and substrate mobility. But on the coast there is a strong marine influence of salinity and storms. However, dunes can be classified according to the form of their base in:

• Barján: C or crescent -shaped dune that is generated in areas where the sand supply is limited. Its surface is hard, flat and lacks vegetation.
• Longitudinal dune: elongated and rectilinear dune that forms in parallel to the predominant wind. The amount of grains of sand is limited.
• Transversal Duna: They are long ridges separated by depressions oriented with straight angles with respect to the constant direction wind. They occur in places where the accumulation of sand is abundant and covers the ground completely.
• Parabolic dune: They are dunas in the form of U whose ends are oriented in the direction contrary to the wind (that is, the other way around the barján). They are typical of coastal areas, where vegetation partially covers the earth.
• Duna in star or pyramidal: Isolated hill with several ridges that start from the top. They are formed when there are large concentrations of sand and wind directions are variable.
• Duna Barjanoid: It constitutes an intermediate form between isolated barjanes and extensions of transverse dunes.

Dunes have great importance, since:

• They protect the coasts of erosion Acting as natural defenses and preventing the sea, for example, progress inland through waves, currents and swells. We recommend reading this article about wind erosion: definition, types and examples.
• They constitute a Great sand filter able to absorb rainwater and store it in depth.
• They provide sand by helping the maintenance of large beaches.
• Provide a conducive habitat for the Native Flora and Fauna Development.
• They are beautiful sites that foster tourism, education, research and spiritual enrichment.

Here are examples of dunes around the world:

• Duna Federico Kirbus: Located in El Bolsón de Fiambalá, in the province of Catamarca, in the Argentine Republic. It is the largest dune on the planet.
• Duna Grande or Cerro March: It is the highest dune in Peru and the second highest in the world.
• Duna La Reyna: Present at the Sonora desert, Mexico, in the El Pinacate Biosphere Reserve and Great Altar Desert.
• Dune from Sossusvlei: In Namibia in Namib-Naukluft National Park.
• Sahara desert dunes: In North Africa.

Now that you know what the dunes are and how they form, do not miss these articles on the types of deserts and the largest deserts in the world.

If you want to read more articles similar to Dunes: What are they, how they form, types and importancewe recommend that you enter our category of ecosystems.