Within a watershed, the drainage network is made up of rivers, lakes, and aquifers. Being true to what our eyes see, we normally think that the water flows that exist are only superficial, but we forget that aquifers, which are geological structures that not only allow the storage of fresh water, but also its circulation. Therefore, there are underground rivers, which circulate through caves and other cavities and perhaps we have been closer to them than we think, without knowing what we were visiting.
If you want to know what underground rivers are like or how to find them, be sure to read this interesting article by Ecologist Verde about what are underground rivers and how are they formed, where you can also discover other formations closely related to these rivers, such as cenotes and underground lakes.
The underground rivers are bodies of water that flow through channels not visible from the surface of the earth, since they are located in the subsurface depths.
Its origin may be natural, so that natural underground rivers They are fed by rainwater and can traverse or traverse underground cave systems or caverns. However, there are also artificial underground rivers, which have been created by human beings, as a consequence of urban development and mining activity. For example, the surveys carried out in the Alzola sima-mine region (Guipuzkoa) in the last century have given rise to an important network of caves and galleries through which the waters of the underground river Mondmilch or Moon Milk River circulate, since its water is white.
These underground rivers, whether natural or artificial, transport sediments (mainly calcareous, since this mineral is related to their origin, as explained in the next section) that in some cases end up feeding the sandy strip of the beaches in the that flows. However, seas and oceans are not the only final destinations for the waters of these rivers, as they can also flow into springs or be pumped for extraction by drilling wells.
In the formation of underground rivers and other structures of the subsurface water system, such as cenotes and underground lakesKarst geomorphological processes, which lead to dissolution and collapse of limestone, play a very important role. That is, due to the action of water, either from precipitation or thaw, the soluble rocks are diluted and fractured, giving rise to cavities and interconnected caverns, which allow the passage of the river current.
When accentuated water erosion, it is possible that the ceiling of these underground cavities is weakened, which favors the formation of cenotes. These sinkholes or depressions in the ground, very close to the surface and in contact with the outside, that accumulate water, can be considered underground lakes created by dissolution processes (dissolution lakes). The cenotes are connected to each other thanks to the underground rivers and they differ from these in the way in which the impermeable layer of the aquifer systems is arranged. In cenotes and lakes, the impermeable layer forms a depression that allows the accumulation of water, while in underground rivers this layer remains inclined, favoring the circulation of water through the hydraulic potential.
Finally, it should be noted that cenotes are very abundant and important in the Yucatan Peninsula, where the Ring of Cenotes stands out, formed about 66 million years ago by the impact of a meteorite.
Have you ever wondered where are underground rivers? Below you will be able to know the name of some of these geological formations located throughout the world:
If you were wondering about the longest underground rivers in the world, take note that the longest navigable underground river in Europe stands out in Spain. Located within the limits of the Serra d'Espadà Natural Park, in the Vall d'Uixó, we are talking about the underground river of more than 3 km in length that runs through the caves or grottos of Sant Josep.
Other of the best known underground rivers and the country in which they are found are:
To further expand your knowledge about fresh water, we recommend reading these other articles on How groundwater is formed and How rivers are formed.
If you want to read more articles similar to Underground rivers: what they are and how they formWe recommend that you enter our Nature Curiosities category.