Groundwater: the concept, level and protection of groundwater. Sanitary and hygienic characteristics of water sources

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Water is the source of life on Earth, without it it is difficult to imagine the activities of modern man. Water is used for various purposes: drinking and household needs, watering cattle. Those who live in the private sector away from the city, know that the main sources of drinking water are wells, wells or kaptazhi. In this or that case, it is necessary to conduct water on its own. Of great importance is the determination of the exact location of the water-bearing vein. The location of water-bearing veins varies in depth, which greatly affects the quality of water.

Each level of the water-bearing has its own characteristics. Depending on this, several types of underground veins are distinguished: verkhovodku, ground and interplastic waters. The latter are divided into pressure and non-pressure. They are the most clean, but at the same time, they are the hardest to reach. Hydrogeological features are important not only when conducting water pipes, but also in construction. In this case, the level of groundwater standing is of great importance. Let us consider in more detail, what is the difference between perchage, groundwater and interstitial water, what is their depth of occurrence.

Aquifer layers of the earth

In the thickness of the earth there are several aquifers. Water accumulates in the ground due to the presence of waterproof layers. The latter are formed, to a greater degree, by clay. Clay practically does not pass water, thus protecting the aquifers from contamination. Less often in the waterproof layer, you can find stones. An interesting fact is that between clay layers there are almost always layers formed by sand. It is known that sand retains moisture (water), as a result of which water accumulates and thereby forms the aquifers of the earth. It is necessary to know that aquifers can be protected by waterproof layers on both sides or only with one.

The deepest aquifer, which is used in modern times for water consumption, is formed by artesian waters. It can be located at a depth of more than 100 meters. Artesian waters lie not in the thickness of sand, but in a layer formed of limestone. Due to this they have a special chemical composition. There are also more accessible aquifers. These include vagrancy. Of great importance is that it is not protected from above by a waterproof layer, therefore it is not suitable for drinking needs. Aquifers in some parts of the terrain can be thin, and in others - very large. This is observed as a result of fracture of the waterproof layers. Such sites have a large production rate.

Verkhovodka and its features

The very first aquifer is called perch. The name of this water is due to the fact that the layer is located very close to the surface. The depth at which it can be detected is from 1 to 4 meters. Verkhovodka refers to non-pressure underground waters. Such water is not everywhere, therefore it is a variable aquifer. Verkhovodka is formed as a result of the filtration of surface waters or precipitation through the soil. Because of this, it was not widely used for drinking needs. There are several reasons for this:

• low debit and its inconstancy;
• presence of a large number of pollutants;
• the inability to fully meet the needs of the population.

Verkhovodka is formed periodically. It depends on the presence of precipitation, floods. In the warm season (summer), finding this source of water is very difficult. Often, it is located on the first waterproof layer, so when this layer leaves, a swampy area may form. The water of this aquifer is characterized by its freshness and low mineralization. In addition, it is contaminated with organic substances. In some cases, it contains a lot of iron. It can be suitable for household needs as an additional source of water for irrigation or plant irrigation.

Characteristics of groundwater

Determining the level of standing of groundwater in private construction is very often observed. They are most often used for water supply in the residential sector. Wells or kaptazhi are built for groundwater abstraction. Wells are more often drilled for interplastic waters. Groundwater forms the first permanent aquifer that lies on the first waterproof layer of the earth. They are non-pressure. This indicates that they are not protected from above by waterproof rocks of the ground, and the layer of earth remains half filled at the same time.

They are distributed almost everywhere, in contrast to perchovodki. It is important that groundwater depends largely on precipitation, so their production may vary depending on the season. In spring and autumn it is more than in summer and winter. The level of this layer repeats the configuration of the relief, so in different territories the thickness of this layer is different. Water, which accumulates in alluvial bowels, is widely used for drinking. Groundwater lies at a level of several meters to dozens. The chemical composition and mineralization are determined by the location of the layer. If there are surface sources (rivers, lakes) with fresh water in the vicinity, the underground layers can be used for drinking, washing and other purposes. But this requires their cleaning (boiling or filtering).

Interplastic aquifers

When choosing an aquifer for a future well or well, it is necessary to know that inter-reservoir waters are better (clean) than groundwater.

Inter-layer waters are characterized by the fact that they are surrounded from above and below by water-resistant layers.

The depth at which they can be detected is between 10 and more meters. There are non-pressure and pressure interstitial water. The former are not so widely distributed, they are very difficult to find. They occur in layered sediments, at the top of the geological section. In terms of their chemical composition, they are more balanced and clean, therefore they are used for water supply.

The most popular are pressure water, called artesian. It is established that their chemical composition is constant. They are rich in various minerals. Such water can be drunk even without preliminary treatment. Protection of this aquifer is from above and below. Their debit is always large, and it is constant. The depth of their location is about 100 meters and more. It is for obtaining artesian water that a well is drilled. Artesian water refers to minerals of great value.

How does the quality of water depend on the depth of the aquifer?

With the location of aquifers, it is considered that water quality improves as depth increases. This is actually so. During the private construction of wells or wells, the first water begins to appear at a depth of 2-3 meters from the surface. This is the water of the first aquifer. It is contaminated with chemicals, organic, which comes from the surface. Wastewater is of great importance, which easily penetrates into the first aquifer. When constructing a well, the optimal digging depth is 15-20 meters.

Here there are groundwaters and interplastic ones. To detect artesian veins, you need to dig further. It is better to use drilling. Thus, the occurrence of aquifers is of great importance for water supply of the population. Many regions experience a shortage of clean water, which is the reason for seeking new sources.

For the purpose of water supply, groundwater, open water and atmospheric water can be used.
   1. Groundwater
   Underground waters are formed mainly by filtering atmospheric precipitation through the soil; a small part of them is formed as a result of filtration of the water of open water bodies (rivers, lakes, reservoirs, etc.) through the channel.

The accumulation and movement of groundwater depends on the structure of the rocks, which, in relation to water, are divided into waterproof (waterproof) and water-permeable. The water-resistant rocks are granite, clay, limestone; to water permeable include sand, gravel, pebble, fractured rocks. Water fills the pores and cracks of these rocks. Underground waters are divided into soil, ground and interplastic by the conditions of occurrence.

a) Soil water (surface or perchage) is most closely located to the earth's surface in the first aquifer, they do not have protection in the form of a waterproof layer, therefore their composition varies sharply depending on hydrometeorological conditions. Most of them accumulate in the spring, they dry up in the summer, they freeze in winter. They are easily exposed to pollution, as they are in the zone of seepage of atmospheric waters and therefore they should not be used for water supply purposes.

b) Groundwater is located in subsequent aquifers; they accumulate on the first waterproof layer, do not have a waterproof layer from above, and therefore water exchange takes place between them and surface waters. Groundwater is non-pressure, their level in the well is set at the level of the underground water layer. They are formed due to seepage of atmospheric precipitation and the water level is subject to large fluctuations in different years and seasons. Groundwater is more or less constant in composition and better quality than surface water. Filtering through a fairly large layer of soil, they become colorless, transparent, free of microorganisms. The depth of their occurrence in various localities varies from 2 m to several tens. Groundwater is a common source of water supply in rural areas.



Once, at a geography lesson, the teacher called me to the blackboard and suggested drawing a diagram allocation of waterin natureEarth. I, slightly offended by such an easy task, sketched out the plan of the planet, designated parts of the World Ocean and began to list the names of the largest seas, rivers and lakes. "Everything?" - asked the teacher when I finished. I podnapryagsya and remembered a few ponds less. The teacher continued to look at me inquiringly. I, blushing, blurted out about the puddles and very recalled the atmospheric moisture. Master sighed and set me a quartet. "You completely forgot about the groundwater", He explained my assessment. Of course, today I would have answered his task quite differently.

General information about groundwater

Underground waters are part of the Earth's hydrosphere, located in the surface layers of its crust. Despite its underground nature, they are found in liquid, solid and gaseous states. According to the nature of occurrence and circulation, groundwater is divided into pore(in clastic rocks like sand), veining(in rock formations) and karst(in soluble rocks - limestones, gypsum and so on).

In the place of occurrence, groundwater has the following classification:

• soil;
• ground;
• interplastic;
• artesian;
• mineral.

What is groundwater

Groundwater is consideredthe first water from the surface  constantly existing aquifer  (the soil does not form it). As a rule, groundwater is free and does not have an impermeable layer above itself. The level of these waters is constant fluctuatesbecause of many factors: the volume of precipitation, climatic conditions (drought drains them, and severe frosts are quite capable of causing freezing), human economic activity and so on.

What is interplastic water and how do they differ from groundwater

Interplastic waters - the "second" floor of the underground aquifer. Their the level is more constant than that of groundwater. Since the interplastic waters are "compressed" from above and from below by other layers, they are under pressure, sometimes quite significant.

There are three main differences between interplastic and groundwater:

• location  (the ground is closer to the surface);
• lack of pressure near groundwater;
• greaterdegree of pollution of soil.

Underground waters are in the upper part of the earth's crust. These waters feed rivers, lakes and marshes. They are important in people's lives.

Groundwater formation

After the rain, water seeps through the pores and cracks in the loose water-permeable sedimentary rocks (sands, gravels). There it accumulates in aquifers over water-resistant rocks (granite, marble, clay), which do not flow or very poorly flow through the water. Underground waters can lie at various depths, sometimes up to 12-15 kilometers, and be in a liquid, solid and vapor state.

Soil and interplastic water

According to the nature of the occurrence of groundwater are divided into ground and interstitial. Ground waters are the waters of the first from the surface of the aquifer. They lie on the waterproof, and from above are blocked by water-permeable rocks. These waters are relatively shallow, so they can be widely used for economic purposes (wells), but they are easily polluted.

Between the two water-resistant layers lie interstitial water. Sometimes, lying deep in the deep, interplastic waters are under pressure. If you make a well, they can break out into the surface in the form of a fountain.

Sources of information

Outcrops of groundwater to the surface are called sources (or springs). Of particular value are mineral springs, the waters of which contain dissolved gases and salts, as well as thermal springs of hot (thermal) waters warmed by the warmth of the Earth. The waters of these springs are used for medicinal purposes.

In some areas where there are many active volcanoes, boiling underground waters and gases in the form of geysers break through the cracks in the earth's crust. Geyser (from the Icelandic word gcysa - gushing) is a source that periodically throws out fountains of hot water and steam. Geysers are found in, in, North America and. The heat of hot underground water is used for heating.

Significance and protection of groundwater

Underground waters regulate the level of water in rivers and lakes. They are used for drinking water supply, for supplying water to industrial enterprises, and in arid areas for irrigation.

Replenishment of groundwater is slow, so their intensive use can lead to the fact that they run out. The purification of groundwater is almost impossible, which is why it is important to ensure that contaminated sewage does not reach the earth's surface.

Interplastic waters are underground waters lying between two watertight layers.

According to the conditions of occurrence, the interplastic waters can be non-pressure and pressure, in the latter case they are called artesian. Interplastic non-pressure waters are relatively rare and are of theoretical interest, as a possible occurrence of groundwater. Normally, non-pressure inter-reservoir waters lie in strata lying above the erosion basis of a given area.

Interplastic waters, as their name indicates, are blocked from the surface by a waterproof roof that separates the area of ​​feeding from the area of ​​their distribution. Therefore, the temperature of interstitial waters is not subject to such abrupt fluctuations as the temperature of groundwater and usually only annual fluctuations in temperature are noticeable. Pressurized water is subjected to hydrostatic pressure due to the difference in levels in the areas of power and output. A direct line connecting the supply level of pressurized waters with the output level is called the piezometric level line (Fig. 1).

Picture 1. Artesian Basin Scheme:

a-area of ​​supply; 6-region of pressure; в-unloading area; AV line of piezometric level.

If a well is drilled at some point in the location of the pressure water, the water rises in it to the piezometric level line. Consequently, if the line of the piezometric level passes above the daytime surface, there will be a flowing.

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In order to determine the conditions for the occurrence of groundwater, as shown, hydroisogyps maps are a good illustration. To determine the conditions of occurrence of artesian waters, such an illustration is horizontal lines connecting points with the same piezometric level-hydro-isopyose or piezoisogypsum (Fig. 2).

Figure-2. Map of piezoisogypsum:

  1-horizontals of the earth's surface; 2-horizontals of the aquifer roof; 3- piezoisogypsum.

In addition hydroisopyzes on hydrogeological maps show in isolines the markings of the roof of the pressure aquifer. Such isolines are called isohypses of the waterproof roof. Artesian waters are formed during the mulliform or synclinal bedding of layers, as well as in flexures, entangled layers, etc. (Fig. 3).

In the tundra-like occurrence of artesian waters, the aquifer may wedge out or its facies change, as a result of which the artesian horizon disappears. With subsequent dislocations, part of the aquifer may be isolated, containing so-called buried waters.

Figure 3. Schemes of the formation of artesian waters:

  a-artesian waters in the syncline; b-facies change in the aquifer; c-formation of pressure waters in a monoclinic; r-ejection of the aquifer

Geological structures of more or less significant size, containing artesian water, are called artesian basins. In the European part of the USSR, the Moscow Artesian Basin, the Dnieper-Donetsky, the Black Sea and others are distinguished. Small artesian basins are formed in mountain folded areas.

Water pressure in such areas is due to the fact that sandy-gravel formations of piedmont plumes as they move away from the mountains overlap with clayey deposits. Similar basins are found in foothill and intermontane plains, for example, in Transcaucasia and Central Asia. Artesian basins are of great importance for supplying the population with benign drinking water.

Fissured and veined waters

In massive rocks, groundwater can only move and move around in places where rock continuity is disturbed. Layered rocks such as dolomites, sandstones, limestones, and crystalline schists are prone to cracking. The water resistance of fractured rocks may vary depending on the nature of the cracks, the conditions for their formation and further development. There are areas where numerous cracks in the rocks are the thinnest and therefore not aquiferous, and wide water-bearing cracks are located at large distances drugoy.V and from areas of strong tectonic movements formed a dense network of fine cracks aquifer.

It should be noted that very often large water-bearing cracks are subsequently clogged with settling clay particles or mineral minerals (silica, lime spar and other oxides) falling out of the water. Cracks are usually found in areas below the level of the greatest erosion erosion. A significant amount cracked waters refers to tectonic fissures formed as a result of movements of the earth's crust. In rocks that are easily eroded or dissolved by water, the water-bearing cracks increase and the movement of water in them acquires a more intensive character.

Fissured waters moving in large cracks of tectonic formation or in eroded cracks in sedimentary rocks are called vein waters. These are relatively free watercourses of low power, similar to their character to the waters flowing in trays and pipes. According to the nature of occurrence, vein and fissured waters can refer to groundwater water or to interplastic, pressure or non-pressure.

Residential groundwater is distinguished by sharp fluctuations in level and temperature, even when they lie relatively deep. Often they are contaminated with microorganisms, suspended mineral and organic substances. Residual interstitial waters have a more stable temperature regime, but the degree of their contamination with microorganisms remains for the most part the same as that of vein groundwater.

Springs or springs

Springs, or springs, are called natural outcrops of groundwater on the surface of the day. They are formed as a result of the intersection of the aquifer by the surface of the relief. There are four types of springs feeding: perch; groundwater; interplastic waters; veins and fissured waters. The sources feeding on the perch are located in the aeration zone above the groundwater level. The regime of such springs is unstable, sometimes they disappear completely, and then arise again.

In contrast, sources that feed on groundwater operate continuously. Typically, the water of such sources is unpronounceable, only in rare cases there is a local support. Therefore, the ground sources are descending, associated with the slope of the waterproof layer. Ground sources are erosive (Fig-1), contact and iridescent. sources of education from the opening of the interplastic aquifer, are permanent. They cease to give water only in cases where the water-bearing horizon dries up. In addition to constantly operating sources, springs sprinkled and siphon sources (figure-1) may occur, when the water completely fills the underground bowl.

Picture 1. Sources of Education

a-formation of the erosive descending source at the opening of the groundwater of the river valley; b-formation of a contact descending source when the contact of the aquifer is broken; c-formation of the iridescent source at the trough-like occurrence of the waterproof layer; r-formation of a siphon source; d-formation of sources in the valley, revealing the interplastic waters of the synclinal fold; e-formation of sources at the base of the deluvial cloak, overlapping the output of interplastic waters; g-the formation of ascending sources at the opening of the artesian horizon; з = formation of ascending sources along fault cracks; I-sources.

If rising water flows to the daytime surface, an ascending source is formed. Ascending sources also include geysers in which the head is caused by the action of water and gas vapors dissolved in water. The outgoing sources can occur on artesian slopes or in artesian basins, (as shown in Figure -1, g) or climb up the pressure veins (Fig. 1, 3). The conditions for the formation, occurrence and regime of groundwater are different and depend on hydrological, hydrometeorological and geological factors, Understanding groundwater is of great importance in the compilation of their classification.