Classification of groundwater according to the conditions of formation. Groundwater formation processes

Sources of groundwater

Sources of groundwater

As a result of the overflow of the aquifer, water is poured onto the surface of the earth in the form of sources of groundwater (springs, springs). Some springs appear only after heavy rains and dry up quickly after the precipitation is over.

Hundreds of millions of liters of water are poured to the surface from artesian pools every day.

The springs are not limited to surface waters only. Scientists recently discovered hot springs in the oceans at a depth of about 2.5 km, mainly along the mid-ocean ridges. The hot water (over 300 degrees Celsius) from these springs is rich in minerals and sulfur, creating a unique ecosystem where an unusual and exotic underwater world thrives.

How are sources formed?

Groundwater sources can flow from various aquifers. There are many small springs and springs.

The largest springs are formed in karst ...

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Underground water sources

General characteristics of underground water supply sources

Groundwater refers to the waters in the upper layers of the earth's crust. Groundwater is formed as a result of atmospheric and surface water seeping into the ground.

These waters practically do not contain suspended matter, in most cases colorless, but almost always highly mineralized, having in their composition salts of calcium, magnesium, iron, manganese. Groundwater is classified both by individual characteristics and by the nature of their movement in the aquifer.

If we proceed from the qualitative and quantitative characteristics, then they can be classified according to the nature of occurrence, temperature, chemical composition, degree of mineralization.

By the nature of the occurrence, groundwater can be divided into upper water (waters of the aeration zone), groundwater and artesian.

The upper watershed near the surface of the earth (1 - 5 m) cannot serve as a reliable source ...

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These are waters found in the rocks of the earth's crust. There is much more underground water than surface water on land - rivers, lakes, swamps. They arise due to the percolation of atmospheric precipitation into the depths of the earth. The most important condition for the formation of groundwater is the ability of rocks to pass water. Distinguish between permeable and waterproof (waterproof) rocks.
Water permeability of rocks
Rocks that allow water to pass through are called permeable rocks. These are loose porous (sand, pebbles, gravel) or hard but fractured rocks (limestone, sandstone, shale). The larger the particles and pores, the better the water permeability. Rocks that do not allow water to pass through are waterproof or waterproof. These are clays or any uncracked solid rocks. Water from the surface seeps through permeable rocks until it encounters waterproof layers in its path. Here it lingers, gradually filling the pores or cracks of permeable rocks. Formations saturated ...

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The groundwater

Underground water There are underground rivers, seas and lakes on the planet.
There are rivers that flow underground only occasionally appear on the surface of the planet. There are many such rivers all over the world. There are underground rivers, lakes and even seas.

How groundwater is formed

When it rains and downpours over the earth, water enters the soil. Some of it evaporates back into the sky, and the rest penetrates deep into the earth. As it seeps through the rock mass, the water slowly moves downward. When it reaches the granite layers, it is in this place that water accumulates. A river is formed when the granite layer is at an angle, and lakes are formed when streams meet a basin in their path.

Rivers underground can flow many hundreds of kilometers. Such a big river exists in the Sahara. Recently there was evidence of scientists that perhaps an underground river flows under the Amazon.

Sometimes these rivers come to the ground in the form of a spring, a geyser and even a waterfall. The river flowing under ...

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610 Groundwater Sources

Groundwater is the waters of the upper part of the earth's crust (up to a depth of 12-16 km)

They are located in the pores and cavities of rocks in a liquid, solid or vapor state. They are formed mainly from the seepage into the depth of atmospheric precipitation during rains or melting of snow, ice and ice. from magma On the plains, composed of sedimentary rocks, Usually your property alternates layers of different water permeability Some of them are easily permeable to water (sands, gravel, pebbles) and are called permeable, others retain water (clays, crystalline shales) and are called done-penetrating On waterproof rocks the ox lingers, fills the gaps between the particles of permeable rock and forms an aquifer. There may be several such horizons in the same area, sometimes 10-1 10-15.

Under the terms ...

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Land waters are rivers, lakes, reservoirs, glaciers, swamps, as well as underground waters (Table 1).

Table 1. Waters of land

The groundwater

Among land waters, the largest reserves are found in groundwater, the total reserves of which are 60 million km3. Groundwater can be in liquid, solid, vaporous state. They are located in the soil and rocks of the upper crust.

The ability of rocks to pass water depends on the size and number of pores, voids, cracks.

In relation to water, all rocks are divided into three groups: permeable (they pass water well), waterproof (retain water) and soluble.

Soluble rocks are potash and sodium chloride, gypsum, limestone. When groundwater dissolves them, large voids, caves, craters, wells are formed at depth (this phenomenon is called karst).

Permeable rocks can be divided into two categories: permeable in their entire mass ...

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Grade 6 textbook

Geography
Geography

Section 41. Groundwater

Remember

What happens to water that falls on the ground with rain? Through which rocks does water seep faster - sands or clays? What are springs (keys)? Why is the water cold in the spring even in summer?

How groundwater is formed. Water in the earth's crust is in three states: liquid, gaseous and solid. Water and steam fill the gaps between the rock particles.

Solid water consists of crystals and layers of ice in frozen rocks.

Groundwater is the water found in the rocks of the earth's crust.

There is much more groundwater than surface water of the land - rivers, lakes, swamps. They arise due to the percolation of atmospheric precipitation into the depths of the earth. The most important condition for the formation of groundwater is the ability of rocks to pass water. Distinguish between permeable and waterproof (waterproof) rocks ...

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Groundwater Groundwater

Water in the bowels of the Earth is in liquid, solid and gaseous state. It either freely circulates through the cracks and pores of rocks and soils, obeying the force of gravity, or is in a physically and chemically bound state with the mineral particles of soils, soils and rocks.

Groundwater - waters that are in the thickness of the earth's crust in all physical states.

Theories and hypotheses of the origin of groundwater

For a long time, there were two theories that denied one another - the theory of infiltration and the theory of condensation. In the first, it was argued that the accumulation of underground water is the result of the percolation of atmospheric precipitation into the soil and ground, in the second, that the source of the origin of groundwater is atmospheric water vapor, which, together with air, enters the cold layers of the earth's crust and condenses there.

According to Lebedev (1919), the soil and ground are enriched with water both due to the percolation of atmospheric precipitation, and in ...

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The groundwater

All the waters of the earth's crust that are below the surface of the Earth in rocks in gaseous, liquid and solid states are called groundwater.

Groundwater is part of the hydrosphere - the water shell of the globe. They are found in boreholes at a depth of several kilometers. According to V.I. Vernandskiy, groundwater can exist up to a depth of 60 km due to the fact that water molecules are dissociated by only 2% even at a temperature of 2000 ° C

Approximate calculations of fresh water reserves in the bowels of the Earth to a depth of 16 kilometers give the value of 400 million cubic kilometers, i.e. about 1/3 of the waters of the World Ocean.

The accumulation of knowledge about groundwater, which began in ancient times, accelerated with the emergence of cities and irrigated agriculture. The art of building dug wells up to several tens of meters was known for 2000-3000 thousand years BC. in Egypt, Central Asia, India, China. In the same period, treatment appeared ...

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The volume of groundwater exceeds the volume of surface water on land. Water in the earth's crust can be not only liquid, but also gaseous and in the form of ice. Water turns into ice in frozen rocks.

The reason for the formation of groundwater is the percolation of atmospheric precipitation through the rocks of the earth's crust. There are rocks that let water through, and there are those that do not let it through. The former are called permeable, and the latter are waterproof.

Rainwater that falls to the surface of the earth seeps through the permeable layers until it encounters a waterproof layer. As a result, just above the water-resistant layer, the rocks are saturated with water and turn into aquifers.

Water-permeable rocks are sand, pebbles, gravel, limestone, sandstone, shale. These rocks are either loose or fractured. Clays and hard rocks, in which there are no cracks, are water-resistant.

Underground water flows the way the surface is inclined - with more ...

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CHAPTER 8 GEOLOGICAL ACTIVITIES OF GROUNDWATER

Groundwater includes all waters in the pores and cracks of a mountain city. They are widespread in the earth's crust, and their study is of great importance in solving issues: water supply to settlements and industrial enterprises, hydraulic engineering, industrial and civil construction, land reclamation, resort and sanatorium business, etc.

The geological activity of underground waters is great. They are associated with karst processes in soluble rocks, the sliding of earth masses along the slopes of ravines, rivers and seas, the destruction of mineral deposits and their formation in new places, the removal of various compounds and heat from deep zones of the earth's crust.

Groundwater, its origin, distribution, migration, qualitative and quantitative changes over time and geological activity are the subject of study of a special science - hydrogeology, one of the branches of geology.

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Section: Water | and in subsections: types of water. | Author-compiler of the article: Lev Alexandrovich Debarkader

We continue to replenish the section "Water" and the subsection "Types of water" with new types of water. Today our guests are underground waters. We will talk about what underground waters are, where they come from and where they go. Along the way, we will dispel a couple of common misconceptions about groundwater.

Groundwater is the collective name for a variety of underground water deposits. The water under the ground is fresh, very fresh, brackish, salty, super-saline (for example, in cryopegs, which we touched upon in the article "The Diversity of Water in the World").

What all interesting types of groundwater have in common is that they are located above a watertight layer of soil. A waterproof soil layer is soil that contains a large amount of clay (does not allow water to pass through) or solid rock with a minimum of cracks.

If you go outside and spread a sheet of polyethylene on the ground, then ...

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THE GROUNDWATER

Water resources are distinguished according to the degree of their suitability for use. The highest class includes those waters that are most stable over time in terms of volume

mu and high quality. Such properties are possessed by the underground waters of the upper aquifers from the so-called zone of active water exchange. In addition, there is a lesser risk of their contamination by sewage, household and industrial waste. Water resources of surface runoff are considered less valuable.

The Crimean peninsula is relatively poor in fresh groundwater, nevertheless, they are of great importance in the national economy of the region. The distribution and conditions of their formation depend on local, primarily climatic and geological factors. In general, the accumulation of groundwater occurs through the seepage (infiltration) of atmospheric precipitation that has fallen over a given surface, either as a result of an influx from the side of already formed groundwater, or penetration into ...

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How is the formation of groundwater

Underground waters are waters located below the surface of the earth. Their physical state can be any, but for economic purposes, it is liquid water reserves that are of interest. To use this resource optimally, an answer is required on how groundwater is formed and what types they are.

Groundwater is unevenly distributed. In the deepest layers, which consist of high-density rocks formed by magmatic and metamorphic processes, there is little moisture. Its main part is located in the surface layers, consisting of rocks of sedimentary origin.

The water reserves of the upper part are divided into three more layers. The moisture of the top layer is most often fresh and is used for a variety of needs. In the middle layer, mineralized waters are found. Below there are brines with high salinity and significant content of iodine, bromine and some other minerals.

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Types of groundwater

Underground water sources, for the most part, are considered strategic water resources.
Aquifers, moving under the influence of their own gravity, form free-flow and pressure-bearing horizons. The conditions of their occurrence are different, which makes it possible to classify them into types: soil, subsoil, interstratal, artesian, and mineral.

Differences in groundwater

Soil waters fill pores, cracks and all gaps between rock particles. They are considered to be a temporary accumulation of drip water in the surface layer and are not associated with the lower aquifer.

Groundwater - forms the first water-resistant horizon from the surface. This layer experiences some fluctuations in different seasons, that is, an increase in the level in the spring-autumn period and a decrease in the hot season.

Interstratal waters, in contrast to groundwater, have a more constant level in time and lie between two stubborn layers.

Filling the whole ...

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The other day I bought a regular mineral water bottle. Deciding to read about its origin on the label, I found an inscription that said that this water was spilled from an underground source. I was very interested in the topic of groundwater and its origin. So...

How groundwater is formed

It's worth starting with what underground waters are. In essence, these are the waters that are in the strata of rocks. Moreover, they can be in both liquid and solid and gaseous states.

But speaking of groundwater, we mean its liquid type. They are distributed very unevenly. In the deepest layers, which are formed from especially dense rocks (created by magmatic and metamorphic processes), there is practically no moisture.

The main part of the water lies precisely in the surface layers, the rocks of which are distinguished by sedimentary origin.

But back to the topic of the formation of groundwater. It can happen in several ways.

The main method is considered to be moisture seepage from the surface. This process is called "infiltration". Here, groundwater is enriched not only by precipitation, but also by all surface water reservoirs. In this case, the amount of moisture directly depends on the type of soil.

The second method can be called the precipitation of water vapor, which occurs in the cavities of rocks. This is a rather long process.

Types of groundwater

The formation of groundwater can be called a constant and endless process. That is why such waters are considered to be an inexhaustible resource.

But the types of groundwater deserve special mention. There are three main ones:

• top water. It lies closest to the ground surface. This type of water is unstable; during drought it can easily evaporate;
• ground. They differ in the stability of their recharge, this is the "main type" of groundwater. The volume of which is influenced by many factors;
• and artesian. They are "pressure". They are under pressure and often occupy large areas.

It is worth noting that it is artesian waters that are classified as minerals. We all need to remember the importance of preserving them.

The conditions for the formation of groundwater are largely predetermined by the filtration properties of rocks, which characterize their ability to pass water through themselves.

The degree of water permeability of soils is characterized by the filtration coefficient Kf. It expresses the filtration rate in m / day or m / s with a hydraulic slope t = 1. Rocks for which K f values ​​are less than 0.1 m / day are conventionally considered waterproof, since, unlike water-permeable ones, they practically cannot be drained by conventional ones. ways (see table 5.1).

Filtration properties of soils depend on their particle size distribution and porosity. The larger the soil grains and, consequently, the pores between them, the higher the water permeability.

In unbound soils, water can move not only due to gravitational forces (filtration), but also capillary ones. In this case, groundwater is pulled up through thin voids, and the upper layers of the soil are moistened due to the aquifers of the lower ones. This property of soils is characterized by the maximum height of capillary rise (see Table 5.2)

2.2 Formation and formation of groundwater

Groundwater is formed as a result of seepage (infiltration) of atmospheric precipitation into the ground, as well as condensation of water vapor in their pores and voids. Aquifers are formed between water-resistant layers, creating zones with different degrees of saturation and types of water recharge.

Rice. 14. Scheme of the formation of groundwater

I - aeration zone; 2 - saturation zone (aquifer);

3 - waterproof layer; 4 - waterproofing.

a - top water and suspended waters; b - groundwater; c - interstratal waters.

The uppermost aeration zone - serves as a kind of "buffer" layer between groundwater and the surface, regulating the flow of water from the atmosphere into the aquifer and accumulating capillary water in its lower part, hydraulically connected with the aquifer. Atmospheric precipitation from the earth's surface penetrates into this zone, mainly due to free percolation. The greatest amount of moisture in the aeration zone accumulates in weight after snow melting, and in summer it partially evaporates, is transported by plants or seeps into the underlying layers, where aquifers are formed.

Top water and suspended waters are formed when there are separate waterproof lenses in permeable soils, or when low-permeable soils do not have time to pass the moisture coming from above, these waters are characterized by unrestrained spread, a level that changes sharply over time, and can completely disappear with the cessation of feeding.

The upper water gradually flows down from the waterproof lens, feeding the underlying aquifer, and the suspended waters, which are retained in low-permeable layers only by the force of capillary tension, freely seep into the permeable layer.

Despite the episodic presence in soils, waterlogging and suspended water, close to the surface of the earth, in some cases cause swamping of the territory and flooding of underground structures.

Ground water are the first permanent aquifer from the surface of the earth and lie on an impermeable layer that is consistent in area. The area of ​​their feeding coincides with the area of ​​distribution. Lying not deep from the surface of the earth, these waters most often cause flooding of urban areas.

Meformation waters separated from the day surface by a water-resistant layer and have mismatched areas of recharge and distribution, as well as areas of the outlet of the water-bearing layer to the earth's surface (zone of natural drainage). If these waters occur at relatively shallow depths, then they can cause flooding of local areas at the foot of the slopes or more extensive areas with ground-pressure feeding of the upper aquifer.

Groundwater can be free-flow, if they have a free surface, and pressurized, in the presence of a waterproof roof. Pressure the waters are under hydrostatic pressure and come to the surface at the intersection of the aquifer by rivers, ravines or artificial cuts (these waters are called artesian waters).

The surface of groundwater is displayed on the map by hydroisogypsum and hydroisobaths (see Fig. 15).

Fig. 15. Hydroisogypsum and hydroisobaths in the flooded area

Hydroisogypsum - lines of equivalent groundwater level marks.

Hydroisobaths are lines of equivalent groundwater depths.

Groundwater includes all waters in the earth's crust, regardless of their state of aggregation.

Groundwater is formed mainly as a result of the percolation of atmospheric precipitation, as well as by condensation of water vapor that penetrates with air into fractured and porous rocks. In addition, there are buried, or relict (otlat. relictus - abandoned), waters preserved from ancient sea basins and buried during the accumulation of thick sediments, as well as thermal waters formed at the last stages of magmatic processes.

Water in rocks is in different forms: in the form of free and sorbed molecules of water vapor, weakly sorbed polymolecular films, capillary water and, finally, water that can move under the influence of its own weight - gravitational water. The listed forms of water are closely related to different types of pores and cracks.

All rocks have porosity, which is measured by the ratio of the total volume of all types of pores to the total volume of the rock, expressed as a percentage. The porosity of rocks ranges from 20 to 30%.

An important property of rocks is their water permeability - the ability to pass water through themselves. In rocks, gravitational water can most actively move, which moves along the largest pores and cracks. Taking into account the possibility of its movement, permeable and waterproof rocks are distinguished. The former include sands, pebbles, fractured limestones and other rocks, while waterproof ones include clays and massive crystalline rocks.

A permeable rock containing water is called an aquifer, or a reservoir, and a water-impermeable rock is a water-resistant horizon. The water-resistant rock overlapping the water-resistant horizon from above is called roof, and the underlying one is his sole.

The gravitational water filling the pores of the reservoir can be under pressure, and then they speak of confined waters, or confined aquifers. If there is no pressure, then the aquifers are called non-confined. In this case, the water can only move under the influence of its own gravity. Water under pressure is able to rise to a height that balances this pressure (the effect of communicating vessels).

The absolute height of the pressure water rise is called the piezometric level. As a rule, the magnitude of the pressure in the aquifer is due to the relatively high position of the aquifer recharge area. If such a horizon is opened by drilling, then the water in the borehole will rise to the level at which the recharge area is located. Such waters are called artesian (after the name of the province of Artois in northwestern France, where such a well was first drilled).

A tectonic trough, in the geological structure of which there is one or usually several confined aquifers, is called an artesian basin.

An example is the artesian basin near Moscow, in the cavernous limestones of the Carboniferous age of which there are three pressure water aquifers of high quality fresh water, separated by water-resistant clays.

The upper water table is called the water table. This horizon has only an underlying aquiclude and is formed due to the infiltration of atmospheric precipitation, which is retained at the aquiclude. Therefore, the mirror (upper level) of groundwater is located at different depths, depending on the terrain and the amount of precipitation.

Above the groundwater horizon during the period of rains or melting of snow, due to the slow filtration of rain or spring melt water, a "hanging" (without a confining layer) a thin horizon of the so-called top water may appear. This horizon exists for a short time during certain seasons of the year.

Groundwater confined to a system of aquifers, separated by layers of water-resistant rocks, are called interstratal, or simply stratal. As noted earlier, they can be pressurized and non-pressurized.

In mountainous countries, there are fractured waters confined to fractured areas of crystalline massifs, as well as juvenile waters associated with post-volcanic processes. The sources of these waters, enriched with various mineral compounds and often possessing increased radioactivity, such as, for example, the sources of the Mineralnye Vody region in the North Caucasus, are used for medicinal and balneological purposes.

In places where aquifers come to the surface, springs are formed. Among them, there are sources of groundwater and free-flow interstratal waters, which are called descending, and sources of pressure water, called ascending.

On the 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 surface structures and all underground ones are associated with the need to account for the movement of groundwater, their composition and condition. The physical and mechanical properties and state 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 waterlogging of the territory. Groundwater can be an aggressive environment for rocks. They are the main reason for many physical and geological processes occurring in natural conditions, during the construction and operation of engineering structures.

Distinguish:

Drinking water- water, in terms of its quality in its natural state or after processing, meets regulatory requirements and is intended for drinking and domestic needs of a person, or for the production of food products. This type of water also includes natural mineral table waters, which include underground waters with a total salinity of not more than 1 g / dm3, which do not require water treatment or do not change their natural composition after water treatment.

Technical groundwater - waters of various chemical composition (from fresh to brines), intended for use in production, technical and technological purposes, the quality requirements of which are established by state or industry standards, technical specifications or consumers.

Groundwater is also subdivided:

Groundwater is mainly formed as a result of seepage (infiltration) of atmospheric precipitation and surface water into the earth's crust. Water flows through permeable rocks to the water-resistant layer and accumulates on it, forming an underground basin or stream. This underground water is called infiltration... The amount of infiltration water depends on the climatic conditions of the area, relief, vegetation, composition of 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. Condensing groundwater is formed only in summer and partly in spring and autumn, and in winter it is not formed at all. AF Lebedev explained the formation of significant reserves of underground water in the zones of deserts and semi-deserts, where the amount of atmospheric precipitation is negligible by the condensation of water vapor. 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. In the course of geological development, buried water basins can be preserved in the thickness of the earth's crust. The water contained in the sedimentary strata of these basins is called relict.

The formation of groundwater is a complex process that begins with the accumulation of sediments and is closely related to the geological history of the region. Very often, groundwater of various origins mixes with each other, forming mixed by the origin of the water.

The upper part of the earth's crust, from the point of view of the distribution of groundwater, is usually divided into two zones: the aeration zone and the saturation zone. In the aeration zone, not always all pores of rocks are filled with water. All waters of the aeration zone are nourished by atmospheric precipitation, intensively evaporated and 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 the rocks are always filled with water. Above the saturation zone, there is a capillary humidification subzone. In this subzone, fine pores are filled with water, and large ones with air.

In the aeration zone, soil water and upper water are formed. Soil water lies directly at the surface of the earth. This is the only water that does not have a water seal under it and is represented mainly by bound and capillary water. Soil water is in a complex relationship with animals and plants. It is distinguished by sharp temperature fluctuations, the presence of microorganisms and humus. Builders encounter soil water only in swampy areas.

Verhovodka formed in the aeration zone on waterproof lenses. Any temporary accumulation of water in the aeration zone is also called high water. Atmospheric precipitation that penetrates this zone can temporarily linger on low-permeability or compacted layers. Most often this occurs in the spring during the period of snow melting or during the period of heavy rains. During dry periods, the perch may disappear.

The characteristic features of the upstream are the inconstancy of existence, limited distribution, low power. Verkhovodka often creates difficulties for builders, since the presence or possibility of its formation is not always established during engineering geological surveys. Formed upstream water can cause flooding of engineering structures, waterlogging of territories.

Ground is called the water that occurs on the first permanent waterproof layer from the earth's surface. Groundwater exists constantly. They have a free water surface called a mirror of groundwater, and waterproof bed. The projection of the groundwater mirror onto a vertical plane is called groundwater level (UGV). The distance from the aquiclude to the groundwater level is called the thickness 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 supply is mainly due to 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 the aquifer is called the area of ​​nutrition groundwater. The area of ​​groundwater recharge always coincides with the area of ​​their distribution. Ground waters, due to the presence of a free water surface, are free-flowing, that is, the water level in the well is set at the same mark at which the water is encountered.

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

Groundwater, being in constant motion, has a close connection with surface watercourses and water bodies. In areas where precipitation prevails over evaporation, groundwater usually feeds rivers. underground drinking aquifer artesian

In arid regions, very often water from rivers enters groundwater, replenishing underground streams. There may also be a mixed type of connection, when from one side the groundwater feeds the river, and from the other, the water from the river enters the ground flow. The nature of the connection may vary depending on climatic and some other conditions.

When designing and building engineering structures, it is necessary to take into account groundwater regime, that is, the change over time of indicators such as fluctuations in the level of groundwater, 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 the level of groundwater. Floods on rivers, as well as reservoirs, ponds, irrigation systems, canals, drainage structures lead to a change in the groundwater regime.

The position of the groundwater table is depicted on maps using hydroisohypsum and hydroisobaths. Hydroisogypsum- 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 movement of groundwater and to determine the value of the hydraulic gradient.

The direction of movement of groundwater is always perpendicular to the hydroisohypsum from higher to lower elevations. The directions along which groundwater moves with a steady motion that does not change in time are called streamlines. If the streamlines are parallel to each other, then such a flow is called flat. The stream can also be converging and diverging. The smaller the distance between the hydroisohypsum, the greater the hydraulic gradient of the soil flow. Hydroisobates- lines connecting points with the same groundwater depth.

Interstratal groundwater refers to aquifers that lie between two aquicludes. They can be non-pressurized and pressurized.

Interstratal non-confined waters are rare. By the nature of the movement, they are similar to groundwater. Interstratal pressure waters are called artesian. The occurrence of artesian waters is very diverse, but synclinal is the most common.

Artesian water always fills the entire aquifer from bottom to top and has no free water surface. The area of ​​distribution of one or more levels of artesian aquifers is called artesian basin. The areas of artesian basins are huge and are measured in tens, hundreds, and sometimes thousands of square kilometers.

In each artesian basin, areas of feeding, distribution and discharge are distinguished. The recharge area of ​​artesian basins is usually located at large 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 the marks of the feeding area and the discharge area, according to the law of communicating vessels. The level at which artesian water is established in the 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 with wells, gushing will occur, and the head is called positive.

When the piezometric level is located below the surface of the earth, then the head is called negative, and water does not pour out of the well. Artesian waters are generally more saline and less associated with surface watercourses and bodies of water than groundwater.

Fissured waters called underground waters confined to fissured igneous, metamorphic and sedimentary rocks. The nature of their movement is determined by the size and shape of the cracks. Fractured waters can be non-confined and confined. They are fickle and can change the nature of their movement. The erosion and dissolution of rocks lead to the expansion of cracks, and the crystallization of salts and the accumulation of sediments - to their narrowing. Fracture water flow can reach 500 m3 / h. Fractured waters pose significant difficulties in the construction of underground structures.

I came across an article with theories of the origin of groundwater. They were reasoned enough for me to agree with each one. After analyzing them, I made a list of the conditions necessary for the formation of underground streams of different types.

Conditions for the formation of groundwater

The list of necessary components for the formation of waters:

1. Presence of atmospheric precipitation, as well as various reservoirs and rocks that have the ability to pass water (infiltration theory).
2. Air where water vapor is concentrated (condensation theory).
3. Accumulation of sedimentary rocks, in the thickness of which sea waters are buried in a various state (sedimentary waters).
4. The presence of gaseous substances that are released during the cooling of magma (juvenile theory).
5. The presence of irrigation canals (artificial).
6. Accumulation of mineral masses that contain gas-liquid elements or crystallization water. Temperature and pressure provoke dehydration (metamorphogenic waters).

Personally, I believe that the lion's share of groundwater nevertheless arose from sediment seeping and accumulating in the soil layers. In this case, the properties of the underlying rocks are important. So, crushed stone, sands, gravel are perfectly permeable to water. They are permeable. But clay, marble and granite cannot boast of such capabilities, so they were called waterproof. However, it is possible to distinguish another group of easily soluble rocks, which are simply washed out by water flows, making cracks, voids. Examples are gypsum and salts.

Types of groundwater

As it has already become clear, the sources of water are precipitation and water vapor. The second component in this flow formation mechanism is soil, which has a varied layered structure. It determines the conditions (position) of groundwater occurrence.

Hence, three types of aquifers are distinguished:

• soil water, which is concentrated in the uppermost soil layer;
• groundwater, which are located after the uppermost aeration zone on a water-resistant layer;
• interstratal, flow under conditions of constriction by two interlayers of water-resistant rocks.