In the integral water cycle, aquifers have a key function. In this sense, rainwater infiltrates the field, occupying pores and cracks of the subsoil, giving rise to underground runoff. Water is stored in aquifers and is likely to be exploited through collection works to meet human needs. The lack of control over these collection activities generates great pressures on these formations and their operation, so that the natural recharge of aquifers can be modified, changing space-time patterns of availability of water resources. To avoid these impacts, it is important to know the dynamics and characteristics of these water storage systems.
In this ecology article, you can discover what aquifers are and how an aquifer is formed, but we will focus more on knowing what the different ones are Types of aquifers that exist.
What is an aquifer and how many types exist
Aquifers are geological formations with hydraulic properties that allow the storage and free transmission of water through its pores or cracks. Among the parts of an aquifercan be distinguished:
- The water table.
- The saturation zone.
- The waterproof layer.
He groundwater It is located in the saturation zone, below the water table, which constitutes the upper limit of this area. The greater the depth of the saturated area, the greater the water pressure. Since stored water flows to areas of lower pressure, emanates to the surface naturally through upwelling (Hullas), slopes, springs or river channels. In addition, depending on the type of aquifer, there is a waterproof zone that prevents the passage of water.
The aquifer recharge It takes place through the infiltration-percollation of precipitated water. They intervene: gravity and lithology.
- On the one hand, gravity is the force that attracts water to the center of the earth, allowing its vertical circulation, from the earth’s surface to the different depths of the subsoil.
- On the other hand, the lithology determines the degree of porosity or compaction of the geological materials that constitute the aquifer. Depending on this, water may accumulate and circulate more or less easily.
If you want to know in more detail what an aquifer is and how it is formed, here we leave you this other summary of ecology. There are different criteria for classify aquifers that exist. In this article, four types of classifications are established.
Classification according to hydrogeology
Depending on lithological behavior against groundwater, 4 are differentiated Hydrogeological systems: aquifers, aquitatos, aquacuid and aquifugos.
- According to their geological formations, The aquifers They can be considered excellent (formed by clean gravels), regular-good (formed by clean sands, gravels and sands or fine sand) or poor (fine sand, silly and fractured limestone) for the storage and transmission of groundwater. In general, this system is characterized by a high capacity to store, drain and transmit water.
- The aquitorsformed by alms, silty sands and clays, have a high capacity to store water but have problems for their drain (medium-low capacity) and its transmission (low capacity). It is an intermediate term between what is an aquifer and an aquacuid.
- The characteristic formations of The aquacuid Despite having high porosity, they are impervious to the passage of water (marls, clay or pumice stone). Therefore, its storage, drainage and transmission capacity is void.
- The aquifuges They are geological formations that cannot store or transmit water. Some examples are the igneous rocks that are neither cracked or fractured. Here you can learn more about the types of igneous rocks and their characteristics.
Classification according to hydraulic pressure or aquifer pressure
The location of aquifers, their hydrological behavior and the characteristic geology, give rise to three Types of aquifers Different: free, confined and semiconfined.
- Free, not confined or water table aquifers They do not present waterproof formations. In them, the non -saturated area is located between the surface of the land and the water table and the water are in contact with the air and atmospheric pressure.
- Confined, captive, pressure or load aquifersunlike free aquifers, they are not in contact with the atmosphere due to the presence of waterproof or confining materials. In a captive or confined aquifer, the water saturates in its entirety the pores or cracks, so that when performing perforations it ascends until the hydraulic pressure with the atmospheric is balanced.
- Semi -confined aquifersthey are also pressure aquifers, such as those confined, but unlike the latter, there is greater permeability (they are considered aquitors).
According to lithological characteristics
Lithology allows you to distinguish two Types of aquifers: detritic and carbonated (or karst):
- Detritic aquifersthey are free aquifers in contact with the rivers, which are mainly formed by clay materials, very little permeable. They can also contain accumulations of detritic materials, sands and gravels, highly permeable and porous. This makes its permeability variable.
- Karst or carbonated aquifers They are formed by limestone and dolomatic materials, which allow the accumulation of rain and runoff, due to their dissolution (high permeability).
According to texture
According to the properties of its texture, Aquifers can be: porous or cracked.
- In Porous aquifers The water saturates the pores, interconnected, which confers permeability and ability to transmit the water. This varies according to the formation material.
- In the cracked aquifersthe water is located in the fissures of the rocks, which are also communicated. Water circulation, as it is fissures and not pores, is less predictable and more heterogeneous.
Now that you know the different classifications of the types of aquifers, we encourage you to learn more about continental waters: what are, characteristics and importance with this other ecology article.
If you want to read more articles similar to Types of aquiferswe recommend that you enter our category of other environment.
