What is a estuary, how it is formed and examples

A estuary is a long and narrow geomorphological accident that enters From the coast to the interior And it occurs as a result of the flooding of a river valley due to the increase in sea level, due to the sinking of the coastal edge or for both causes.

They are usually sites of great ecological importancesince they offer a wide variety of habitats for various species. They also make up sites of scientific, social and tourist interest, not only for the beauty of their landscapes but for the activities that can be carried out such as fishing, navigation and fauna sighting.

Next we will detail what are the steps in the formation of a estuary:

1. Formation of the river valley: In the first place, a river must form a river valley furrowed by a river that culminates in the ocean. The characteristics of the valley, such as width and depth, depend on the erosive activity of the river and the geological composition of the land.
2. Sea level increase: The increase in sea level product of glaciers melting or by tectonic subsidence causes marine water to begin flooding the river valley. This phenomenon, known as marine transgression, carries marine water into the coast. Learn more about the increase in sea level: causes and consequences.
3. Flood of the Valley: As the time takes place, the river valley begins to flood, thanks to the sea currents and waves.
4. Formation of a estuary: Due to this series of processes, once the river valley is flooded it becomes a estuary. Its entrance is usually wider and more deep due to the greater erosive capacity of marine water and its movement, while the internal part becomes narrower and less depth. This geographical configuration facilitates the mixture of sweet and salty waters, resulting in a rich and diverse ecosystem.
5. Dynamics and transformation: Rías can be modified over time by sedimentation processes, erosive and changes in sea level. Sediment deposition can modify the depth and width of the estuary, while erosion can change its form. In addition, climate change and human activities can also influence their evolution, affecting their biodiversity and ecological dynamics.

Here are the main differences between a river and a estuary:

• Definition: A river is a current of continuous fresh water, more or less caudalous, which flows in a direction from its birth, to its mouth. On the other hand, a estuary is a coastal accident that is produced by the flooding of a river valley, as a consequence of the increase in sea level.
• Training: A river is formed by the accumulation of rainwater or thaw that flows from higher than lower areas. On the contrary, a estuary is usually formed by the increase in sea level.
• Ecosystems: The rivers are freshwater ecosystems that provide reproduction, shelter and food sites to a wide variety of aquatic species such as fish, amphibians, reptiles, birds, as well as mammals of semi -communication habits; While a estuary constitutes ecosystems where fresh water is mixed with salt water and different species that can survive both in sweet and saline environments coexist.

You may be interested in reading this article about the river parts and its characteristics.

Here are the main differences between a estuary and a fjord:

• Definition: A fjord is a glacier valley flooded by the ocean that is characterized by its deep waters surrounded by narrow steep walls. A estuary is a river valley flooded with ocean water, less deep, resulting in a mixture of fresh and salted water.
• Training: The fjords are formed by the intense activity of the glaciers over thousands of years, which, by advancing from the mountains to the sea, erodes the terrain. When the ice was melted and the sea level is flooded giving rise to the fjords. The formation of the estuaries, however, are not associated with glacial processes.
• Location: The rias are typical of flatter coasts such as the northwest of the Iberian Peninsula. Fjords are in regions previously affected by glaciations, such as Norway and parts of Canada.

In this post you will find more information about what a fjord is and how it is formed.

• Ría de Vigo: Located in the south of Pontevedra, it is the deepest of the low grades of Galicia. Being easy access and peaceful waters, it constitutes an ideal site for navigation and water sports. Also, its waters are rich in nutrients due to the outcrop of the northern waters.
• Ría del Burgo: Located in La Coruña, Galicia, the Burgo’s estuary belongs to the High Rías within the Arabra Gulf. Did you know that it was declared as the most contaminated estuary of the European continent because of the industrial spills it receives?

• Celestún Ria: Located in the Yucatan Peninsula in the states of Yucatán and Campeche, the Celestún estuary is a biosphere reserve and a Ramsar site of vital importance for the conservation of wetlands. It is also an ideal site for ecotourism in which pink flamingos and other migratory birds can be observed.
• Ría Lagartos: In northern Yucatan is the Lagartos estuary, declared a biosphere reserve in 1979. The reserve covers approximately 60,000 hectares and includes mangroves, marshes, and bodies of fresh and salty water. This estuary forms an important site for the survival of seabirds and reptiles such as crocodiles and turtles.

• Ría de Bahía Blanca: The Bahía Blanca estuary is a marine estuary in the southeast of the province of Buenos Aires. It forms an important commercial and fishing port, hosting the port of engineer White, one of the largest in the country.
• Desired Ría: On the Atlantic coast in the province of Santa Cruz is the desired estuary whose surroundings (protected by the protected natural area desired) are formed by rocky and cliff landscapes that offer refuge and reproduction areas for many species.

Now that you know what a estuary is, we invite you to read this article about the Delta: what it is, how it is formed and types.

If you want to read more articles similar to What is a estuary, how it is formed and exampleswe recommend that you enter our category of ecosystems.