Salinization of aquifers: what is and why it occurs

The salinization of aquifers can be defined as the process by which the concentration of salts and minerals of groundwater deteriorating your quality parameters.

This process is considered a type of Pollution of soils and waters that most affects the coastal aquifers. Under normal conditions, in these geological formations, fresh water reserves remain in contact with sea salt water, keeping both water masses a certain equilibrium relationship. However, there are numerous causes, of natural or anthropic origin, which can trigger or accelerate salinization processes.

Due to tourist, agricultural, urban and population pressures that support coastal ecosystems, the Spanish Mediterranean coast can be taken as an example, it presents serious aquifer salinization problems. In fact, it is estimated that from a total of 95 masses of existing underground water (MASB), around 56 have salinization problems.

As indicated in the previous section, the reasons why the salinization of water from aquifers occurs They can be of natural or anthropic origin.

Natural causes of the salinization of aquifers

• If we take into account that one of the most important sources of water entry into aquifers are rainfall, it is possible to think that irregularities in rainy regimes can favor the salinization of their reserves. For example, in periods of drought or in regions with dry climates, where evapoSpiration is superior to annual precipitation, it can increase the accumulation of salts and minerals in water.
• Salinization can also be favored by lithology and physical-chemical characteristics of the land (texture, porosity, permeability, moisture retention capacity and cation exchange). In this sense, when rainwater runs through saline soils, it is able to drag and transport salts and minerals that end up incorporating into the mineralogical composition of underground water reserves.
• Among other natural factors that can favor saline intrusion, the presence of salt water aquifers, the proximity of lowlands to the coast, the presence of swamps, coastal lakes and mines.

Anthropic causes of the salinization of aquifers

• First, among the causes of contamination of groundwater reserves by salts, the Overexploitation of aquifers as the great trigger for this phenomenon. With the collection of large volumes of groundwater, water reserves are reduced, which causes a decrease in the water table and, consequently, the lateral displacement of the salt wedge inland, which gains in -depth space. Here we talk more about the overexploitation of water: causes, consequences and solutions.
• Climate change can also be indicated as a causal factor. In this sense, the global warming accelerated by humans has caused the thaw of glaciers, translating this into an increase in sea level that, every year that passes, increases the degree of threat on the state of vulnerability of coastal aquifers.
• Likewise, the abnormalities in rainfall are added to the scarcity of the Mediterranean rainfall, the result of the current climatic crisis we live. It could be said that, in general terms, it rains less and, when it rains, important episodes of torrential rains take place, during which, much of the volume of water, due to superficial runoff, flows into the sea without reaching the aquifers. As a result, the lack of fresh water contributions does not compensate for the exit of the appeal of the aquifer (by collection or because it flows to the sea) and the Marine intrusion into an aquifer or in groundwater. In addition, this is aggravated by the sealing of the land for the creation of urban areas and roads, which seriously reduces the infiltration capacity and, therefore, of water recharge of the aquifers.
• The spills of the brine, the product of marine water desalination activities, generate serious conditions on aquifers and wet areas. Two examples of areas very affected by this problem, as indicated⁽¹⁾.
• Finally, salinization phenomena can charge faster in those cases where there is a salt water mass below the sweet, either because it was already (salt water aquifer) or because it has penetrated from the sea in the form of saline wedge. So, when extracting water, the hydraulic potential decreases and a vertical hydraulic gradient is generated that favors the rise of salty waters.

We advise you to expand the information with this other article on the contamination of groundwater: causes and consequences.

Once we know the causes of the salinization of aquifers, it is worth asking about the impacts derived from this phenomenon. Below are the negative consequences of the salinization of aquifers that turn out to be more significant:

• The worsening of the quality of the waters generates health, social and industrial and domestic infrastructure conditions, since the PAL acts as a corrosive agent.
• Saline stress caused in vegetation leads to physiological and biochemical changes that compromise their survival and that of other living beings for those of a power supply.
• In relation to the latter, agriculture is so threatened that 40% of European winter vegetable supply is in danger⁽²⁾. However, agriculture is no exception, there are also many difficulties that can intervene in the normal development of other socio -economic activities.

If you want to learn more about underground water masses, we encourage you to read this other article about underground rivers: what they are and how they form.

If you want to read more articles similar to Salinization of aquifers: what is and why it occurswe recommend that you enter our category of other environment.