Groundwater may exist. Properties and composition of groundwater

A significant part of the Earth's water reserves are underground pools that flow through the soil and rock layers. Huge accumulations of underground water - lakes, which wash away rock deposits and soil, forming pits.

The importance of soil fluid is great not only for nature, but also for humans. Therefore, researchers carry out regular hydrological observations of its condition and quantity, and are studying more and more deeply what groundwater is. Definition, classification and other issues of the topic will be discussed in the article.

What is underground water?

Groundwater is water located in the interlayer spaces of rocks located in top layer earth's crust. Such water can be presented in any state of aggregation: liquid, solid and gaseous. Most often, groundwater is tons of flowing liquid. The second most common are blocks of glaciers that have been preserved since the permafrost period.

Classification

The division of groundwater into classes depends on the conditions of their occurrence:

• soil;
• ground;
• interstratal;
• mineral;
• artesian.

In addition to the listed types, groundwater is divided into classes depending on the level of the layer in which they are located:

• The upper horizon is fresh groundwater. As a rule, their deep location is small: from 25 to 350 m.
• The middle horizon is the location of mineral or saline liquid at a depth of 50 to 600 meters.
• The lower horizon is a depth of 400 to 3000 meters. Water with a high content of minerals.

Groundwater located at great depths can be young in age, that is, recently appeared, or relict. The latter could be laid down in underground layers along with the ground rocks in which it was “located.” Or relict underground water was formed from permafrost: the glaciers melted - the liquid accumulated and was preserved.

Soil water

Soil water is a liquid that lies in the upper layer of the earth's crust. It is mainly localized in spatial voids between soil particles.

If you understand what soil type underground water is, it becomes obvious that this type of liquid is the most useful, since its surface location does not deprive it of all minerals and chemical elements. Such water is one of the main sources of “nutrition” for agricultural fields, forests and other agricultural crops.

This type of liquid cannot always lie horizontally; its outlines are often similar to the topography of the soil. In the upper layer of the earth's crust, moisture does not have a “solid support”, so it is in a suspended state.

Excessive amounts of soil water are observed in the spring when the snow melts.

Groundwater

The ground variety is water that is located at some depths of the upper layer of the earth. The depth of liquid flow can be greater if it is an arid area or desert. In a temperate climate with periodic, constant precipitation, groundwater does not lie so deep. And with excess rain or snow, ground liquid can lead to flooding of the area. In some places, this type of water comes to the surface of the soil and is called a spring, spring or source.

Groundwater is replenished due to precipitation. Many people confuse it with artesian, but the latter lies deeper.

Excessive fluid may accumulate in one area. As a result of the standing position, swamps, lakes, etc. are formed from groundwater.

Interlayer

What is interstratal groundwater? These are, in fact, the same aquifers as ground and soil aquifers, but only their level of flow is deeper than that of the previous two.

A positive feature of interlayer fluids is that they are much cleaner because they lie deeper. In addition, their composition and quantity always fluctuates within one constant limit, and if changes occur, they are insignificant.

Artesian

Artesian waters are located at depths exceeding 100 meters and reaching 1 km. This variety is considered, and indeed is, the most suitable for human consumption. Therefore, in suburban areas, drilling underground wells is often practiced as a source of water supply for residential buildings.

When drilling a well, artesian water fountains out to the surface, since it is a pressure type of groundwater. It lies in the voids of rocks between water-resistant layers of the earth's crust.

The reference points for the extraction of artesian water are certain natural objects located on the surface: depressions, flexures, troughs.

Mineral

Mineral ones are the deepest and most healing and valuable for human health. They contain a high content of various mineral elements, the concentration of which is constant.

Mineral waters also have their own classifications:

By purpose:

• dining room;
• medicinal;
• mixed.

According to the predominance of chemical elements:

• hydrogen sulfide;
• carbon dioxide;
• glandular;
• iodine;
• bromine

According to the degree of mineralization: from fresh to waters with the highest concentration.

Classification by purpose

Groundwater is used in human life. Their purpose varies:

• drinking water is water that is suitable for consumption either in its natural, untouched form, or after purification;
• technical is a liquid that is used in various technological, economic or industrial sectors.

Classification by chemical composition

The chemical composition of groundwater is influenced by those rocks that are adjacent to moisture. The following categories are distinguished:

1. Fresh.
2. Low mineralized.
3. Mineralized.

As a rule, waters lying in close proximity to the earth's surface are freshwater. And the deeper the moisture is, the more mineralized its composition.

How was groundwater formed?

Several factors influence the formation of groundwater.

1. Precipitation. Precipitation in the form of rain or snow is absorbed by the soil in the amount of 20% of the total amount. They form soil or ground fluid. In addition, these two categories of moisture participate in the water cycle in nature.
2. Melting of permafrost glaciers. Groundwater forms entire lakes.
3. There are also juvenile fluids that formed in solidified magma. This is a type of primary water.

Groundwater monitoring

Monitoring of groundwater is an important necessity, which allows you to track not only its quality, but also its quantity, and in general, its presence.

If the quality of water is examined in a laboratory by examining a sample taken, then exploration of the presence involves the following methods, interconnected with each other:

1. First, the area is assessed for the presence of suspected groundwater.
2. Secondly, the temperature indicators of the detected liquid are measured.
3. Next, the radon method is used.
4. Afterwards, base wells are drilled, followed by core removal.
5. The selected core is sent for research: its age, thickness and composition are determined.
6. A certain amount of groundwater is pumped from wells to determine its characteristics.
7. Based on the base wells, liquid occurrence maps are drawn up and its quality and condition are assessed.

Groundwater exploration is divided into following types:

1. Preliminary.
2. Detailed.
3. Operational.

Pollution problems

The problem of groundwater pollution is very relevant today. Scientists identify the following methods of pollution:

1. Chemical. This type of pollution is very common. Its global nature depends on the fact that there are a huge number of agricultural and industrial enterprises on Earth that dump their waste in liquid and solid (crystallized) form. This waste very quickly penetrates into water-bearing horizons.
2. Biological. Contaminated wastewater from domestic use, faulty sewers - all these are causes of contamination of groundwater with pathogenic microorganisms.

Classification by type of water-saturated soils

The following are distinguished:

• porous, that is, those that have settled in the sands;
• cracked, those that fill the cavities of blocks of rocks and rocks;
• karst, those located in limestone rocks or other fragile rocks.

Depending on the location, the composition of the water is formed.

Reserves

Groundwater is regarded as a mineral resource that is renewable and participates in the water cycle in nature. The total reserves of this type of minerals amount to 60 million km 3. But, despite the fact that the indicators are not small, groundwater is subject to pollution, and this significantly affects the quality of the liquid consumed.

Conclusion

Rivers, lakes, groundwater, glaciers, swamps, seas, oceans - all these are the Earth's water reserves, which are interconnected in one way or another. Moisture located in the soil layers not only forms an underground pool, but also affects the formation of surface reservoirs.

Groundwater is suitable for people to drink, therefore saving it from pollution is one of the main tasks of humanity.

All water located in the thickness of rocks in a solid, liquid or gaseous state is called underground

On continents they form a continuous shell, which is not interrupted even in areas of dry steppes and deserts. Like surface waters, they are in constant motion and participate in the general water cycle in nature. The construction and operation of most above-ground structures and all underground ones are associated with the need to take into account the movement of groundwater, its composition and condition. The physical and mechanical properties and condition of many rocks depend on groundwater. They often flood construction pits, ditches, trenches and tunnels, and when they come to the surface, they contribute to swamping of the area. Groundwater can be an aggressive environment in relation to rocks. They are the main cause of many physical and geological processes that occur in natural conditions, during the construction and operation of engineering structures.

There are:

Drinking water– waters whose quality in their natural state or after treatment meets regulatory requirements and is intended for drinking and domestic human needs, or for the production of food products. This type of water also includes mineral natural table waters, which include underground waters with a total mineralization of no more than 1 g/dm3, which do not require water treatment or do not change their natural composition after water treatment.

Technical underground waters – waters of various chemical compositions (from fresh to brines), intended for use for industrial, technical and technological purposes, the quality requirements of which are established by state or industry standards, technical specifications or consumers.

Groundwater is also divided into:

Groundwater is mainly formed as a result of seepage (infiltration) of atmospheric precipitation and surface water into the earth's crust. Water passes through permeable rocks to the impermeable layer and accumulates there, forming an underground pool or stream. This underground water is called infiltration. The amount of infiltration water depends on climatic conditions terrain, relief, vegetation, composition of the rocks of the upper strata, their structure and texture, as well as the tectonic structure of the area. Infiltration groundwater is the most common.

Groundwater can also be formed by condensation of vaporous water constantly circulating in the pores of rocks. Condensation underground water is formed only in summer and partially in spring and autumn, and in winter it is not formed at all. By condensation of water vapor, A.F. Lebedev explained the formation of significant reserves of underground water in desert and semi-desert zones, where the amount of precipitation is negligible. Not only atmospheric water vapor can condense, but also water vapor released from magma chambers and other high-temperature zones of the earth's crust. Such groundwater is called juvenile .Juvenile Groundwater is usually highly mineralized. During geological development, buried water basins may remain deep in the earth's crust. The water contained in the sedimentary strata of these basins is called relict.

Groundwater formation is difficult process, beginning with the accumulation of sediments and closely related to the geological history of the area. Very often, groundwater of different origins mix with each other, forming mixed according to the origin of the water.

From the point of view of the distribution of groundwater, the upper part of the earth’s crust is usually divided into two zones: the aeration zone and the saturation zone. In the aeration zone, not all the pores of rocks are always filled with water. All water in the aeration zone is fed by precipitation, intensively evaporates and is absorbed by plants. The amount of water in this zone is determined by climatic conditions. In the saturation zone, regardless of climatic conditions, all the pores of rocks are always filled with water. Above the saturation zone there is a capillary humidification subzone. In this subzone, thin pores are filled with water, and large ones with air.

In the aeration zone, soil water and perched water are formed. Soil water lies directly at the surface of the earth. This is the only water that does not have an aquitard under it and is represented mainly by bound and capillary water. Soil water is in a complex relationship with animal and plant organisms. It is characterized by sharp temperature fluctuations, the presence of microorganisms and humus. Builders encounter soil water only in wetlands.

Verkhovodka forms in the aeration zone on waterproof lenses. High water is also called any temporary accumulation of water in the aeration zone. Precipitation penetrating into this zone may be temporarily retained in low-permeability or compacted layers. Most often this happens in the spring during the snowmelt period or during periods of heavy rain. During dry periods, perennial water may disappear. The characteristic features of perched water are the inconstancy of existence, limited distribution, low power and pressurelessness. High water often creates difficulties for builders, since the presence or possibility of its formation is not always established during geotechnical surveys. The resulting perched water can cause flooding of engineering structures and swamping of areas.

Ground called water lying on the first permanent waterproof layer from the surface of the earth. Groundwater exists constantly. They have a free water surface called groundwater mirror, and a waterproof bed. The projection of the groundwater table onto a vertical plane is called groundwater level (U GV). The distance from the aquitard to the groundwater level is called capacity of the aquifer. The groundwater level, and, consequently, the thickness of the aquifer, are variable values ​​and can change throughout the year depending on climatic conditions. Groundwater is recharged mainly from atmospheric and surface waters, but they can also be mixed, infiltration-condensation. The area of ​​the earth's surface from which surface and atmospheric water enters an aquifer is called nutrition area groundwater. The area of ​​groundwater recharge always coincides with the area of ​​its distribution. Groundwater, due to the presence of a free water surface, is free-flowing, i.e., the water level in the well is set at the same level at which the water is encountered.

Depending on the conditions of groundwater occurrence, groundwater flows and basins are distinguished. Ground flows have an inclined mirror and are in continuous movement towards the slope of the aquitard. Ground pools have a horizontal mirror and are much less common.

Groundwater, being in constant movement, has a close connection with surface watercourses and reservoirs. In areas where precipitation dominates evaporation, groundwater usually feeds rivers. In arid areas, water from rivers often flows into groundwater, replenishing underground streams. There may also be mixed type connection, when from one bank groundwater feeds the river, and from the other, water from the river enters the groundwater flow. The nature of the connection may vary depending on climatic and some other conditions.

When designing and constructing engineering structures, it is necessary to take into account groundwater regime, i.e., changes over time in such indicators as fluctuations in groundwater levels, temperature and chemical composition. The level and temperature of groundwater are subject to the greatest changes. The reasons for these changes are very diverse and are often directly related to human construction activities. Climatic factors cause both seasonal and long-term changes in groundwater levels. Floods on rivers, as well as reservoirs, ponds, irrigation systems, canals, and drainage structures lead to changes in the groundwater regime.

The position of the groundwater table on maps is depicted using hydroisohypses and hydroisobaths. Hydroisohypses- lines connecting points with the same absolute elevations of the groundwater level. These lines are similar to the contours of the relief and, like them, reflect the relief of the groundwater table. The hydroisohypsum map is used to determine the direction of groundwater movement and to determine the value of the hydraulic gradient. The direction of movement of groundwater is always perpendicular to the hydroisohypses from higher to lower elevations. The directions along which groundwater moves during a steady, time-invariant movement are called current lines. If the streamlines are parallel to each other, then such a flow is called flat. The flow can also be converging or diverging. The smaller the distance between the hydraulic isohypses, the greater the hydraulic gradient of the ground flow. Hydroisobates- lines connecting points with the same depth of groundwater.

Interlayer Groundwater refers to aquifers lying between two aquitards. They can be non-pressure and pressure. Interstratal non-pressure waters are rare. The nature of their movement is similar to that of groundwater. Interlayer pressure waters are called artesian. The occurrence of artesian waters is very diverse, but the most common occurrence is synclinal. Artesian water always fills the entire aquifer from the base to the roof and has no free water surface. The area of ​​distribution of one or more levels of artesian aquifers is called artesian pool. The areas of artesian basins are huge and measure in tens, hundreds, and sometimes thousands of square kilometers. In each artesian basin, areas of feeding, distribution and discharge are distinguished. The feeding area of ​​artesian basins is usually located at greater distances from the center of the basin and at higher elevations. It never coincides with the area of ​​their distribution, which is sometimes called the area of ​​pressure. Artesian waters experience hydrostatic pressure due to the difference in elevation between the feeding area and the discharge area, according to the law of communicating vessels. The level at which artesian water is installed in a well is called piezometric. Its position is determined piezometric line, or a pressure line, a conditional straight line that connects the supply area with the discharge area. If the piezometric line passes above the surface of the earth, then when the aquifer is opened by wells, flowing will occur, and the pressure is called positive. When the piezometric level is located below the surface of the earth, the pressure is called negative, and water does not flow out of the well. Artesian waters are generally more mineralized and less connected to surface watercourses and bodies of water than groundwater.

By fissure waters called groundwater confined to fractured igneous, metamorphic and sedimentary rocks. The nature of their movement is determined by the size and shape of the cracks. Fracture waters can be non-pressure and pressure. They are not constant and can change the nature of movement. The erosion and dissolution of rocks lead to the expansion of cracks, and the crystallization of salts and the accumulation of sediments lead to their narrowing. The flow rate of fissure waters can reach 500 m 3 /h. Fissure waters create significant difficulties in the construction of underground structures.

Groundwater in the city

In cities, the demand for water is high, but groundwater resources are limited. In many ways, the process of restoration of water resources depends on the state of the urban environment itself and its ecology. This important factor is responsible not only for the volume of underground water resources, but also for the level of their pollution.

In recent years, the study of groundwater in urban spaces has become part of the section of hydrogeology.

Problems arising from the interaction of groundwater with the urban environment include contamination of groundwater through sewage pipes and a decrease in groundwater levels pumping systems, and the threat of groundwater flooding of underground spaces in the urban environment (for example, the metro).

Now the issue of preserving and protecting groundwater from pollution is especially acute. After all, the stability of development of most cities largely depends on them, which brings the problem to a global scale.

Based on the assigned tasks and based on the latest achievements in the field of hydrogeology, scientists are developing new schemes for monitoring and monitoring the level of groundwater pollution and its activity within the underground space of the urban environment.

And yet, no matter what important role its connection with groundwater plays in the development of urban space, it is quite obvious that in this type of interaction the urban environment is assigned the role of an external limiter rather than an equal participant.

Many cities use underground water for drinking water. Everyone knows that water is a renewable resource, but at the same time highly susceptible to the influence of external factors. It is very important to monitor the level of groundwater and the degree of its contamination. For the stable development of urban space, this delicate balance is extremely important. Negligent attitude towards water resources leads to very disastrous consequences. For example, in Mexico City, a constant decline in groundwater levels led to subsidence and then environmental problems.

Groundwater indicators in the Russian Federation

The resource potential of groundwater in Russia is 869.1 million m 3 /day and is distributed unevenly throughout the territory, which is determined by the diversity of geological and hydrogeological conditions and climatic features.

On the European territory of Russia, its value is 346.4 million m 3 /day and varies from 74.1 million m 3 /day in the Central to 117.7 million m 3 /day in the Northwestern Federal District; in the Asian territory of Russia - 522.7 million m 3 /day and ranges from 159.2 million m 3 /day in the Far Eastern to 250.9 million m 3 /day in the Siberian federal districts.

The current role of groundwater in the domestic and drinking water supply of the population of the Russian Federation is characterized by the following indicators. The share of groundwater in the economic balance drinking water supply(from surface and underground water sources) is 45%.

More than 60% of cities and towns meet their drinking water needs using groundwater, and about 20% of them have mixed water supply sources.

In rural areas, groundwater in domestic and drinking water supply accounts for 80–85% of total water consumption.

The most difficult problem is ensuring drinking water population of large cities. About 35% of large cities have virtually no underground sources of centralized water supply, and for 37 cities there are no proven groundwater reserves at all.

The degree of use of groundwater in the household and drinking water supply of the population is determined both by the patterns of distribution of groundwater resources throughout the territory of Russia, and by the policy pursued for many years to provide the population with drinking water through the priority use of surface water.

Currently, there is a low level of use of explored groundwater deposits and their reserves. Average level utilization of total proven reserves is 18–20%, and within exploited fields with proven reserves – 30–32%.

Over the past 5 years, the increase in estimated operational reserves amounted to 6.8 million m 3 /day.

28.2 million m 3 /day of water was taken from underground sources to meet the drinking needs of the population and water supply to industrial facilities. The total amount of groundwater extraction and extraction was 33.1 million m 3 /day, 5.9 million m 3 /day was discharged without use (17.8% of the total groundwater extraction and extraction).

27.2 million m 3 /day was used for household needs, including: for domestic and drinking water supply 20.6 million m 3 /day (76%); industrial and technical water supply – 6.0 million m 3 /day (22%); land irrigation and pasture watering – 0.5 million m 3 /day (2%).

As a result of the extraction and production of groundwater in certain territories, large regional depression craters were formed, the areas of which reach significant sizes (up to 50 thousand km 2), and the level in the center decreased to 65–130 m (the cities of Bryansk, Kursk, Moscow, St. -Petersburg).

In the city of Bryansk, a regional depression crater formed in the Upper Devonian aquifer complex has a radius of more than 150 km and a level drop of more than 80 m. Extensive depression craters formed in the area of ​​​​the cities of Kursk and Zheleznogorsk and at the Mikhailovsky iron ore quarry. The “Kursk” depression funnel in the Batkellovey aquifer has a radius of 90–115 km, the level decrease in the center is 64.5 m. At the Mikhailovsky quarry, the funnel reached a radius of 60–90 km, the level has decreased since the beginning of drainage of the quarry by 77.4 m.

In the Moscow region, intensive exploitation of groundwater in the Lower Carboniferous aquifer complex for 100 years led to the formation of an extensive deep crater, the area of ​​which exceeds 20 thousand km 2, and the maximum drop in level is 110 m. Long-term exploitation of groundwater in the Gdov aquifer in St. Petersburg caused formation of a regional depression funnel with a total area of ​​up to 20 thousand km 2 with a decrease in level to 35 m.

On the territory of Russia, according to state monitoring of the state of the subsoil of the Ministry of Natural Resources of Russia, 4002 sites of contamination have been identified, of which more than 80% are located in groundwater aquifers, which are usually not sources of drinking water supply to the population.

According to expert estimates, in the Russian Federation the share of contaminated groundwater does not exceed 5–6% of the volume of its use for drinking water supply to the population.

The largest number of groundwater contamination sites are located on the territory of the following federal districts: Volga (30%), Siberian (23%); Central (16%) and Southern (15%). Of the total number of groundwater contamination sites:

§ 40% of pollution is associated with industrial enterprises;

§ 20% – with agricultural production;

§ by 9% – with housing and communal services,

§ 4% of pollution occurs as a result of the pull-up of substandard natural waters due to violation of the operating regime of water intakes;

§ 10% of groundwater pollution is “mixed” and is caused by the activities of industrial, municipal and agricultural facilities;

§ for 17% of sites the source of groundwater pollution has not been identified.

The most tense ecological situation has developed in areas where groundwater is contaminated with substances of hazard class I. These areas were identified in the areas of individual large industrial enterprises in the following cities and towns: Amursk (mercury), Achinsk (phosphorus), Baikalsk (mercury), Georgievsk (mercury), Essentuki (mercury), Ekaterinburg (phosphorus), Iskitim (beryllium), Novokuznetsk (phosphorus), Kazan (beryllium, mercury), Kislovodsk (phosphorus), Mineralnye Vody (mercury), Lermontov (mercury), Komsomolsk-on-Amur (beryllium), Magnitogorsk (tetraethyl lead), Novosibirsk (beryllium, mercury), Sayansk (mercury), Svobodny (mercury), Usolye-Sibirskoye (mercury), Khabarovsk (beryllium, mercury), Cherepovets (beryllium), etc.

The greatest environmental hazard is posed by groundwater pollution identified in individual wells at drinking water supply intakes.



Topic: The main types of groundwater. Formation conditions. Geological activity of groundwater

2. Main types of groundwater.

1. Classification of groundwater.

Groundwater is very diverse in chemical composition, temperature, origin, purpose, etc. Based on the total content of dissolved salts, they are divided into four groups: fresh, brackish, saline and brine. Fresh waters contain less than 1 g/l of dissolved salts; brackish waters - from 1 to 10 g/l; salted - from 10 to 50 g/l; brines - more than 50 g/l.

Based on the chemical composition of dissolved salts, groundwater is divided into hydrocarbonate, sulfate, chloride and complex composition (sulfate hydrocarbonate, chloride hydrocarbonate, etc.).

Waters that have medicinal value are called mineral waters. Mineral waters come to the surface in the form of springs or are brought to the surface artificially using boreholes. Based on their chemical composition, gas content and temperature, mineral waters are divided into carbon dioxide, hydrogen sulfide, radioactive and thermal.

Carbon dioxide waters are widespread in the Caucasus, Pamirs, Transbaikalia, and Kamchatka. The carbon dioxide content in carbonated waters ranges from 500 to 3500 mg/l or more. The gas is present in water in dissolved form.

Hydrogen sulfide waters are also quite widespread and are associated mainly with sedimentary rocks. The total content of hydrogen sulfide in water is usually low, but the therapeutic effect of hydrogen sulfide waters is so significant that an H2 content of more than 10 mg/l already gives them medicinal properties. In some cases, the hydrogen sulfide content reaches 140-150 mg/l (for example, the well-known Matsesta springs in the Caucasus).

Radioactive waters are divided into radon waters, containing radon, and radium waters, containing radium salts. The therapeutic effect of radioactive waters is very high.

Based on temperature, thermal waters are divided into cold (below 20°C), warm (20-30°C), hot (37-42°C) and very hot (over 42°C). They are common in areas of young volcanism (in the Caucasus, Kamchatka, Central Asia).

2. Main types of groundwater

According to the conditions of occurrence, the following types of groundwater are distinguished:

· soil;

· high water;

· ground;

· interlayer;

· karst;

· cracked.

Soil water are located near the surface and fill voids in the soil. The moisture contained in the soil layer is called soil water. They move under the influence of molecular, capillary and gravity forces.

In the aeration belt there are 3 layers of soil water:

1. soil horizon of variable humidity - root layer. It is where moisture is exchanged between the atmosphere, soil and plants.

2. subsoil horizon, often “wetting” does not reach here and it remains “dry”.

the horizon of capillary moisture is the capillary fringe.

Verkhovodka - temporary accumulation of groundwater in the near-surface layer of aquifers within the aeration zone, lying on a lens-shaped, pinching out aquitard.

Verkhovodka is free-flowing groundwater that lies closest to the earth's surface and does not have a continuous distribution. They are formed due to the infiltration of atmospheric and surface waters, retained by impermeable or weakly permeable wedging layers and lenses, as well as as a result of condensation of water vapor in rocks. They are characterized by seasonal existence: in dry times they often disappear, and in periods of rain and intense snowmelt they appear again. Subject to sharp fluctuations depending on hydrometeorological conditions (amount of precipitation, air humidity, temperature, etc.). Perched water also includes water that temporarily appears in swamp formations due to excess nutrition swamps Often, perched water occurs as a result of water leaks from water supply systems, sewers, swimming pools and other water-carrying devices, which can result in swamping of the area, flooding of foundations and basements. In the area of ​​distribution of permafrost rocks, perched water belongs to supra-permafrost waters. Verkhodka waters are usually fresh, slightly mineralized, but are often contaminated with organic substances and contain increased amounts of iron and silicic acid. Verkhodka, as a rule, cannot serve good source water supply However, if necessary, measures are taken for artificial conservation: construction of ponds; diversions from rivers that provide constant power to operating wells; planting vegetation that delays snowmelt; creation of waterproof lintels, etc. In desert areas, by installing grooves on clayey areas- takyrakh, atmospheric waters are diverted into the adjacent area of ​​sand, where a lens of perched water is created, which represents a certain supply of fresh water.

Groundwater lie in the form of a permanent aquifer on the first, more or less consistent, waterproof layer from the surface. Groundwater has a free surface, which is called the mirror, or groundwater level.

Interformational waters enclosed between water-resistant layers (strata). Interstratal waters under pressure are called pressure, or artesian. When drilled by wells, artesian water rises above the roof of the aquifer and, if the pressure level mark (piezometric surface) exceeds the mark of the Earth's surface at a given point, then the water will flow out (gush out). The conventional plane that determines the position of the pressure level in the aquifer (see Fig. 2) is called the piezometric level. The height of water rising above the waterproof roof is called pressure.

Artesian waters They lie in permeable sediments enclosed between waterproof ones, completely fill the voids in the formation and are under pressure. The hydrocarbon established in the well is called piezometric, which is expressed in absolute values. Self-flowing pressure waters have a local distribution and are better known among gardeners as “keys”. The geological structures to which artesian aquifers are confined are called artesian basins.

Rice. 1. Types of groundwater: 1 - soil; 2 - perched water; 3 - ground; 4 ~ interlayer; 5 - waterproof horizon; 6 - permeable horizon

Rice. 2. Scheme of the structure of the artesian basin:

1 - waterproof rocks; 2 - permeable rocks with pressure water; 4 - direction of groundwater flow; 5 – well.

Karst waters lie in karst voids formed due to the dissolution and leaching of rocks.

Fissure waters fill cracks in rocks and can be either pressure or non-pressure.

3. Conditions for the formation of groundwater

Groundwater is the first permanent aquifer from the earth's surface. About 80% of rural settlements use groundwater for water supply. GW has been used for irrigation for a long time.

If the waters are fresh, then at a depth of 1-3 m they serve as a source of soil moisture. At a height of 1-1.2 m they can cause waterlogging. If groundwater is highly mineralized, then at a height of 2.5 - 3.0 m it can cause secondary soil salinization. Finally, groundwater can impede the excavation of construction pits, set fire to built-up areas, have an aggressive effect on the underground parts of structures, etc.

Groundwater is formed different ways. Some of them are formed as a result of the infiltration of atmospheric precipitation and surface water through the pores and cracks of rocks. Such waters are called infiltration(the word "infiltration" means seepage).

However, the existence of groundwater cannot always be explained by the infiltration of atmospheric precipitation. For example, in desert and semi-desert areas there is very little precipitation, and it evaporates quickly. However, even in desert areas, groundwater is present at some depth. The formation of such waters can only be explained condensation of water vapor in the soil. The elasticity of water vapor in the warm season in the atmosphere is greater than in soil and rocks, so water vapor continuously flows from the atmosphere into the soil and forms groundwater there. In deserts, semi-deserts and dry steppes, water of condensation origin in hot weather is the only source of moisture for vegetation.

Groundwater can form due to the burial of waters of ancient sea basins together with sediments accumulating in them. The waters of these ancient seas and lakes may have been preserved in buried sediments and then seeped into surrounding rocks or reached the Earth's surface. Such groundwater is called sedimentation waters .

Some of the groundwater in origin may be related to cooling of molten magma. The release of water vapor from magma is confirmed by the formation of clouds and showers during volcanic eruptions. Groundwater of magmatic origin is called juvenile (from the Latin "juvenalis" - virgin). According to oceanologist H. Wright, the vast expanses of water that currently exist “grew drop by drop throughout the life of our planet due to water seeping from the bowels of the Earth.”

The conditions for the occurrence, distribution and formation of humic substances depend on climate, topography, geological structure, the influence of rivers, soil and vegetation cover, and economic factors.

A) Relationship between hot water and climate.

Precipitation and evaporation play an important role in the formation of mountain waters.

To analyze changes in this ratio, it is advisable to use a map of plant moisture availability. Based on the ratio of precipitation to evaporation, 3 zones (regions) are distinguished:

1. sufficient hydration

2. insufficient

3. slight moisture

The first zone contains the main areas of waterlogged lands that require drainage (in certain periods, moistening is necessary here). Areas of insufficient and insignificant moisture require artificial moisture.

In the three regions, the supply of hot water by sediments and their heat to the aeration zone are different.

In the area of ​​sufficient moisture, the infiltration supply of groundwater at a depth of more than 0.5 - 0.7 m prevails over its thermal supply to the aeration zone. This pattern is observed in the non-vegetation and growing seasons, with the exception of very dry years.

In the area of ​​insufficient moisture, the ratio of precipitation infiltration to the evaporation of hot water when it occurs shallowly is different in the forest-steppe and steppe zones.

In forest-steppes in loamy rocks, in wet years, infiltration prevails over thermal hot water into the aeration zone; in dry years, the relationship is the opposite. In the steppe zone in loamy rocks during the non-growing season, infiltration nutrition predominates over thermal hot water, and during the growing season - less flow. In general, over the course of a year, infiltration nutrition begins to dominate over thermal groundwater.

In areas of insignificant moisture - in semi-deserts and deserts - infiltration in loamy rocks with shallow groundwater is disproportionately small compared to the flow into the aeration zone. In sandy rocks, infiltration begins to increase.

Thus, the supply of hot water due to precipitation decreases, and the flow into the aeration zone increases with the transition from the area of ​​sufficient to the area of ​​negligible moisture.

b) Connection of groundwater with rivers.

The forms of connection between groundwater and rivers are determined by the relief and geomorphological conditions.

Deeply incised river valleys serve as groundwater reservoirs, draining adjacent lands. On the contrary, with a small incision characteristic of the lower reaches of rivers, the rivers feed groundwater.

Various cases of the relationship between surface and groundwater are shown in the diagram.

Principal calculation diagram of the interaction of groundwater and surface waters in conditions of variability of surface runoff.

a - low water; b - rising phase of flood; c - descending phase of flood.

V) Relationship between groundwater and pressure water.

If there is no absolutely waterproof layer between groundwater and the underlying pressure horizon, then the following forms of hydraulic connection are possible between them:

1) The groundwater level is higher than the level of pressure waters, as a result of which the flow of hot water into pressure waters is possible.

2) The levels are almost the same. When the groundwater level decreases, for example, by drains, the hot water will be recharged by pressure water.

3) GWL periodically exceeds the level of pressure waters (during irrigation, precipitation), the rest of the time GWL is fed by precipitation.

4) The groundwater level is constantly lower than the groundwater level, so the latter recharges groundwater.

Groundwater can receive nutrition from artesian waters and through the so-called hydrogeological windows - areas where the continuity of the aquifer is broken.

It is possible to recharge hydrocarbons by pressure ones through tectonic faults.

Hydrodynamic zones of hot water, determined by the relief and geological structure, are closely related to the geostructural conditions of the territory. Zones of high drainage are characteristic of mountain and foothill regions. Zones of low drainage are characteristic of troughs and depressions of platform plains.

The zonality of GW supply is most clearly manifested in the zone of low drainage of arid regions. It consists in a consistent increase in the mineralization of hot water with distance from the source of supply of a river, canal, etc. Therefore, in arid areas, wells for water supply are usually placed along canals and rivers.

4. Conditions for the formation and occurrence of artesian waters.

Artesian waters are formed under a certain geological structure - the alternation of water-permeable layers with water-resistant ones. They are confined mainly to synclinal or monoclinal formations of formations.

The area of ​​development of one or more artesian formations is called an artesian basin. ABs can occupy from several tens to hundreds of thousands of km 2 .

Sources of power supply for pressure waters are precipitation, filtration waters of rivers, reservoirs, irrigation canals, etc. Pressure waters under certain conditions are replenished with groundwater.

Their consumption is possible by unloading them into river valleys, coming to the surface in the form of springs, slowly seeping through the layers containing the pressure layer, and flowing into groundwater. The selection of AVs for water supply and irrigation also constitute items of their expenditure.

In artesian basins there are areas of supply, pressure and discharge.

The recharge area is the area where the artesian formation reaches the surface of the earth, where its recharge occurs. It is located at the highest elevations of the artesian basin relief in mountainous areas and watersheds, etc.

The pressure area is the main area of ​​distribution of the artesian basin. Within its boundaries, groundwater has pressure.

Discharge area - the area where pressure water comes to the surface - open discharge (in the form of rising springs or an area of ​​hidden discharge, for example in river beds, etc.)

Wells that tap water flow out, this is an example of artificial discharge of pressure water.

In formations containing gypsum, anhydrides, and salts, artesian waters have increased mineralization.

Types and zonation of artesian waters

Artesian basins are usually classified according to the geostructure of water-bearing and water-resistant rocks.

Based on this feature, two types of artesian basins are distinguished (according to N.I. Tolstikhin):

1. artesian basins of platforms, usually characterized by a very significant development area and the presence of several pressure aquifers (these are Moscow, Baltic, Dnieper-Donets, etc.)

2. artesian basins of folded areas, confined to intensely dislocated sedimentary, igneous and metamorphic rocks. They have a smaller development area. Examples - Fergana, Chui and other basins.

5. Geological activity of groundwater.

Groundwater carries out destructive and creative work. The destructive activity of groundwater is manifested mainly in the dissolution of water-soluble rocks, which is facilitated by the content of dissolved salts and gases in the water. Among the geological processes caused by the activity of PV, karst phenomena should be mentioned first of all.

Karst.

Karst is the process of dissolution of rocks by moving underground and seeping into them surface waters. As a result of karst, caves and voids of various shapes and sizes are formed in rocks. Their length can reach many kilometers.

Of the karst systems, the longest is Mammoth Cave (USA), the total length of which is about 200 km.

Salt-bearing rocks, gypsum, anhydrides and carbonate rocks are susceptible to karst. Accordingly, karst is distinguished: salt, gypsum, carbonate. The development of karst begins with the expansion (under the influence of leaching) of cracks. Karst determines specific relief forms. Its main feature is the presence of karst sinkholes with a diameter of several to hundreds of meters and a depth of up to 20 - 30 m. Karst develops more intensively, the more precipitation falls and the greater the speed of movement of underground flows.

Areas prone to karst are characterized by rapid absorption of sediment.

Within the karst rock massifs, zones of downward movement of water and horizontal movement are distinguished - towards river valleys, the sea, etc.

IN karst caves sinter formations of a predominant carbonate composition are observed - stalactites (growing downwards) and stalagmites (growing from below). Karst weakens rocks and reduces their quantity as a basis for hydraulic structures. Significant leakage of water from reservoirs and canals is possible through karst voids. And at the same time, groundwater contained in karst rocks can be a valuable source for water supply and irrigation.

The destructive activity of groundwater includes suffusion (undermining) - this is the mechanical removal of small particles from loose rocks, which leads to the formation of voids. Such processes can be observed in loess and loess-like rocks. In addition to mechanical, there is chemical suffusion, an example of which is karst.

The creative work of groundwater is manifested in its deposition various connections, cementing cracks in rocks.

Control questions:

1 Give the classification of groundwater.

2. Under what conditions is groundwater formed?

3. Under what conditions are artesian groundwater formed?

4. What is the geological activity of groundwater?

5. Name the main types of groundwater.

6. How does perched water affect construction?

Water is the most common substance on our planet, thanks to which life is supported on it. It is found both in the lithosphere and in the hydrosphere. The Earth's biosphere consists of ¾ water. An important role in the circulation of this substance is played by its underground species. Here it can be formed from mantle gases, during runoff, etc. In this article we will look at the types of groundwater.

Concept

Underground water is understood as the latter, located in the earth's crust, located in rocks located below the Earth's surface in various states of aggregation. They form part of the hydrosphere. According to V.I. Vernadsky, these waters can be located at a depth of up to 60 km. The estimated volume of groundwater located at a depth of up to 16 km is 400 million cubic km, that is, a third of the waters of the World Ocean. They are located on two floors. The lower one contains metamorphic and igneous rocks, so the amount of water here is limited. The bulk of the water is located in the upper floor, in which sedimentary rocks are located.

Classification according to the nature of exchange with surface waters

There are 3 zones in it: the upper one - free; middle and lower - slow water metabolism. Types of groundwater by composition in different zones are different. So, in the upper one there are fresh waters, used for technical, drinking and household purposes. In the middle zone there are ancient waters of various mineral compositions. In the lower part there are highly mineralized brines from which various elements are extracted.

Classification by mineralization

The following types of groundwater are distinguished by mineralization: ultra-, fresh, having relatively high mineralization - only the last group can reach a mineralization level of 1.0 g / cubic meter. dm; brackish, salty, high salinity, brines. In the latter, mineralization exceeds 35 mg/m3. dm.

Classification by occurrence

The following types of groundwater are distinguished according to their occurrence conditions: perched water, groundwater, artesian and soil water.

Verkhovodka is mainly formed on lenses and wedging out layers of low-permeability or water-resistant rocks in the aeration zone during the infiltration of surface and atmospheric waters. Sometimes it is formed due to the illuvial horizon under the soil layer. The formation of these waters is associated with processes of condensation of water vapor in addition to those listed above. In some climatic zones they form fairly large reserves of high-quality water, but mostly thin aquifers are formed, disappearing during drought and forming during periods of intense moisture. Mostly this type groundwater is typical for loams. Its thickness reaches 0.4-5 m. The relief has a significant influence on the formation of perched water. On steep slopes she exists a short time or absent altogether. On flat steppes with saucer-shaped depressions and flat watersheds, a more stable perched water forms on the surface of river routes. It has no hydraulic connection with river waters, and is easily polluted by other waters. At the same time, it can feed groundwater, or it can be spent on evaporation. Verkhodka can be fresh or slightly mineralized.

Groundwater is part of underground water. They are located on the first aquifer from the surface, overlying the first aquifer, consistent in area. Basically they are free-flow waters; they can have a small pressure in areas with local water-impermeable overlap. The depth of occurrence, their chemical and physical properties are subject to periodic fluctuations. Distributed everywhere. They feed through infiltration of precipitation from the atmosphere, filtration from surface sources, condensation of water vapor and intra-ground evaporation, and additional nutrition coming from underlying aquifers.

Artesian water is part of the groundwater that has pressure and lies in aquifers between relatively impermeable and impervious layers. They lie deeper than the ground. In most cases, the areas of nutrition and pressure creation do not coincide. Water appears in the well below the established level. The properties of these waters are less susceptible to fluctuations and pollution compared to groundwater.

Soil waters are those that are confined to the soil water layer, take part in supplying plants with this substance, and are associated with the atmosphere, perched water and groundwater. They have a significant impact on the chemical composition of groundwater when it is deep. If the latter are located shallowly, the soil becomes waterlogged and waterlogging begins. Gravitational water does not form a separate horizon; movement occurs from top to bottom under the action of capillary forces or gravity in various directions.

Classification by formation

The main types of groundwater are infiltration, which are formed due to the seepage of atmospheric precipitation. In addition, they can be formed as a result of condensation of water vapor, which enters fractured and porous rocks along with air. In addition, relict (buried) waters are distinguished, which were in ancient basins, but were buried by thick layers of sedimentary rocks. Also a separate species There are thermal waters that were formed at the last stages of magmatic processes. These waters form magmatic or juvenile species.

Classification of the movement of the objects in question

The following types of groundwater movement are distinguished (see figure).

Infiltration and precipitation from the atmosphere occurs in the aeration zone. In this case, this process is divided into freely carried out and normal infiltration. The first involves movement from top to bottom under the influence of gravity and capillary forces along certain channels and capillary pores, while the porous space is not saturated with water, which helps maintain air movement. During normal infiltration, hydrostatic pressure gradients are added to the forces listed above, resulting in the pores being completely filled with water.

In the saturation zone, hydrostatic pressure and gravity act, which promotes the movement of free water through cracks and pores to the sides, reducing the pressure or slope of the surface of the horizon carrying water. This movement is called filtration. The highest speed of water movement is observed in underground karst caves and canals. Pebbles come in second place. Much slower movement is observed in sands - the speed is 0.5-5 m/day.

Types of groundwater in the permafrost zone

These groundwaters are classified into supra-permafrost, inter-permafrost and sub-permafrost. The former are located in the thickness of permafrost on an aquitard, mainly at the foot of slopes or at the bottom of river valleys. They, in turn, are divided into seasonally freezing, perched water, located in the active layer; into seasonally partially frozen, with the upper part in the active layer, into seasonally non-freezing, the occurrence of which is noted below the seasonally frozen layer. In some cases, the active layer may rupture various soils, which leads to the release of some of the supra-permafrost waters to the surface, where it takes on the appearance of ice.

Inter-permafrost waters can be present in the liquid phase, but are most widespread in the solid phase; As a rule, they are not subject to seasonal thawing/freezing processes. These waters in the liquid phase ensure water exchange with above- and sub-permafrost waters. They can come to the surface like springs. Sub-permafrost waters are artesian. They can be from fresh to brine.

The types of groundwater in Russia are the same as those discussed above.

Contamination of the objects in question

The following types of groundwater pollution are distinguished: chemical, which, in turn, is divided into organic and inorganic, thermal, radioactive and biological.

Chemical pollutants mainly include liquid and solid waste from industrial enterprises, as well as pesticides and fertilizers from agricultural producers. Heavy metals and other toxic elements most affect groundwater. They spread across aquifers over considerable distances. Radionuclide contamination behaves in a similar way.

Biological pollution is caused by pathogenic microflora. Sources of pollution are usually cattle yards, faulty sewers, cesspools etc. The distribution of microflora is determined by the rate of filtration and the survival rate of these organisms.

It is an increase in the temperature of groundwater that occurs during the operation of a water intake. It can occur in areas where waste water is discharged or when the water intake is located near a body of water with warmer surface waters.

Subsoil use

Groundwater extraction as a type of subsoil use is regulated by the Federal Law “On Subsoil”. A license is required to extract these objects. It is issued in relation to groundwater for a period of up to 25 years. The period of use begins to be calculated from the moment of state registration of the license.

Extraction work must be registered with Rosreestr. Next, they draw up a project and submit it for state examination. Then a project for organizing a sanitary zone for underground water intake is prepared, the reserves of these waters are assessed and the calculations are submitted to the State Expertise, the Geoinformation Fund and Rosgeolfond. Next, certificates of land ownership are attached to the received documents, after which an application for a license is submitted.

Finally

What types of groundwater are there in Russia? The same ones as in the world. The area of ​​our country is quite large, so it contains permafrost, artesian, groundwater, and soil water. The classification of the objects under consideration is quite complex, and in this article it is reflected incompletely; its most basic points are shown here.

Groundwater is all the water found below the Earth's surface, where it occupies voids in soils or geological strata. They are replenished by rain, melting snow and other water that seeps through soil, sand or cracks in roads.

Reserves

Groundwater makes up about 20% of the world's reserves, and about 1% of all water, including all water and glaciers.

Scientists say Earth may not be the only planet in the world containing underground water. They may have existed on Mars for a long time. There may also be groundwater on Europa, Jupiter's sixth moon.

The largest accumulation of groundwater is the West Siberian artesian basin, with an area of ​​3 million km². Aquifers began to form in it back in .

Education

Groundwater differs from surface water, which is found in large bodies of the hydrosphere, such as or rivers. Both surface and groundwater are connected through (continuous).

Most groundwater comes from precipitation. They penetrate below the surface of the earth into the soil. When the soil zone becomes saturated, water seeps down below. The saturation zone is where all the voids are filled with water. There is also an aeration zone, where the space is partly occupied by water and partly by air.

Groundwater continues to descend lower until, at some depth, it reaches the rock. Water accumulates in pores and cracks and forms an aquifer, also called an aquifer. The process of sedimentation that increases groundwater volumes is known as recharge. In general, recharge occurs only during the rainy season in or winter in temperate climates. Typically, 10 to 20% of precipitation ends up in aquifers.

Groundwater is constantly moving. Compared to surface waters, this happens very slowly. Actual driving speed depends on bandwidth and the volume of the aquifer. Natural outflow of groundwater occurs through springs and river beds when groundwater pressure is higher atmospheric pressure near the surface of the earth. Internal circulation is not easy to determine, but near the water table the average time for the water cycle may be a year or less, whereas in deep aquifers the process takes thousands of years.

Meaning

Groundwater plays a vital role in the development of arid and semi-arid zones. They are able to support huge agricultural and industrial enterprises that otherwise could not exist. Particularly fortunate is that aquifers that precede the formation of deserts are not affected by aridity over time.

To bring groundwater from underground to its surface, scientists and engineers use special production wells.

Some groundwater dissolves substances from rocks and may contain traces of ancient seawater. However, most groundwater does not contain pathogens and does not require treatment for domestic or industrial use. In addition, groundwater supplies are not severely affected by short droughts and are available in many areas that do not have reliable surface water supplies.

Problems

Scientists are concerned about the problems that arise when too much groundwater is used for everyday life, including homes, businesses and Agriculture. One of the problems is that these waters are moving further and further away from the Earth's surface. Humans are using groundwater faster than rain or snowmelt can replenish the aquifers. This means drilling needs to go deeper to get to the source.

This may not seem very important, but when the groundwater is so far away, the soil and clay that make up surface layer The earth is under stress and becomes weak. Eventually, the weak surface may fall and create a crater. Sinkholes are a serious problem and are found in areas where deep groundwater mining has occurred.