What is groundwater

The definition of groundwater can be summarized as the set of water that is stored deep or below the surface of the ground, completely saturating the pores of the subsoil. Some of the main characteristics of groundwater are:

• Groundwater is sweet.
• The physical, chemical and biological composition of water can be modified once it infiltrates the ground due to its interactions with the environment.
• The major chemical constituents of groundwater are: carbon dioxide (CO2), bicarbonates (HCO3 ^– ), carbonates (CO3 ^2- ), chlorides (Cl ^– ), sulfates (SO4 ^2- ), nitrate (NO3 ^– ), nitrite ( NO2 ^– ), harmonium (NH4 ⁺ ), calcium (Ca ²⁺ ), magnesium (Mg ²⁺ ), sodium (Na ⁺ ), potassium (K ⁺ ), silica (SiO2) and dissolved oxygen (O2).

Groundwater is formed from rainwater . Once the water precipitates, it infiltrates the subsoil and descends until it is retained in an impermeable layer. This layer of the subsoil allows the storage of water, which fully occupies or saturates the pores or holes in the ground, thus forming aquifers.

In this other AgroCorrn article we tell you more about how groundwater is formed .

Groundwater can be classified according to two criteria: according to its formation or its location. Thus, these are some examples of groundwater according to its types.

Depending on the origin or sources of the groundwater, these can be:

• Of infiltration or precipitation.
• Condensation waters from night fog in desert areas.
• Fossils or congenital, which are those bodies of water that were trapped in aquifers thousands of years ago.
• Juvenile or magmatic waters , which are those that emerge for the first time to the surface as a result of volcanic eruptions and geysers (eg: groundwater spring).

Depending on the groundwater distribution on the ground or, in other words, depending on where the groundwater is, we find:

• Edaphic waters: it is the groundwater that is located in the aeration zone or unsaturated zone of the subsoil.
• Suspended waters: they are formed when between the surface and the real saturation zone, there is a thin strip, saturated with water, retained by an impermeable layer.
• Groundwater: the groundwater level waters are those that make up the saturation zone.
• Confined waters: located between two impermeable layers.
• Artesian waters: subjected to great pressure, are stored between impermeable layers, and flow vertically towards the surface.

The biological composition of groundwater can inform us about the quality status of the water resource. The temporal and spatial variability of the biocoenosis is subject to the physical-chemical conditions of the environment and the pressure exerted by humans on the underground water bodies.

Among the unknown and valuable fauna that inhabits groundwater or stigofauna , invertebrates abound (among which arthropods stand out ) that, together with bacteria , play a key role in water purification.

In these other articles you can learn about What are arthropods, their characteristics, classification and examples and about Are bacteria living beings? and the Types of bacteria .

Groundwater is an important water reserve for the consumption of drinking water and the performance of industrial and agricultural activities. In addition to constituting a source of food and allowing economic development, these inland water bodies provide support services , guaranteeing biodiversity, conservation and the proper functioning of ecosystems.

In this other post you will see what is the importance of water .

The overuse of aquifers occurs when aquifer water is extracted more than the natural recharge rate. How groundwater is used makes it less and less available, endangering aquatic ecosystems or those associated with certain bodies of water. For example, the lack of groundwater inflow to coastal wetlands can accelerate saline intrusion processes and thus alter the balance, morphology and dynamics of these ecosystems.

The exponential growth of the population increases the demand for this resource, contributing to its scarcity in terms of availability, as we remember that water constitutes a closed cycle, without losses or gains; it is simply stored in more or less accessible forms and in one physical state or another. In recent decades, alarms have not only been raised due to a decrease in the water reserves that we have due to the consumptive use of water, but also due to the pollution processes that it suffers. Mainly agricultural, urban and industrial activities stand out as triggers for the loss of quality of this resource.

Finally, we advise you to read these other articles about What is an aquifer and how it is formed and the Overexploitation of natural resources, its causes and consequences .