» new types of water. Visiting today - The groundwater. We will talk about what groundwater is, where it comes from and where it goes. Along the way, we’ll dispel a couple of common misconceptions on the topic of groundwater.

Groundwater is the collective name for various deposits of water underground. Water underground can be fresh, very fresh, brackish, salty, super-salty (for example, in cryopegs, which we touched on in the article “Diversity of water in the world”).

Common to all types of groundwater: they are located above an impervious layer of soil. Impermeable soil is soil that contains a large amount of clay (does not allow water to pass through) or soil that is solid rock with a minimum number of cracks.

If you go outside and spread a sheet of polyethylene on the ground, you will get nothing more than a model of a waterproof layer of soil. If you pour water onto polyethylene, it will collect in depressions and flow from higher places to lower ones. A model of groundwater distribution will be obtained. And if you make several holes of different sizes in polyethylene, you will get a model of the penetration of upper waters into the underlying horizons.

Similarly, groundwater reserves are formed where the impervious layer creates depressions. Underground rivers are formed from higher to lower depressions. In places where the waterproof layer is interrupted, the upper waters descend to the lower level.

In the form of a picture it can be represented like this:

Now about where groundwater comes from.

Main source: rain. Rain falls and soaks into the ground. Water penetrates through the loose upper loose layers of soil and accumulates in the depressions of the upper waterproof layer of the earth. This type of water is called "overwater". It depends heavily on the weather - if it rains often, there is water. If it rains less often, there is little or no water. This is also the most contaminated layer of underground water, since filtration through the ground was minimal, and the water contains everything - petroleum products, fertilizers, pesticides, etc. and so on. The depth of this type of water is generally from 2 to 10 meters.

Further, where the upper impervious layer breaks, rainwater enters lower aquifers. Their number is different, the depth of their occurrence is also very different. So, the upper limit starts from 30 meters and can reach 300 and deeper. By the way, for example, in Ukraine, private individuals are prohibited from using water deeper than 300 meters, since this is the country’s strategic reserve.

An interesting pattern is that the deeper the aquifer is located, the less often it contains places of connection with the upper layers. For example, in the Sahara Desert they use groundwater that fell underground in Europe. Another pattern is that the deeper the water, the cleaner it is and the less dependent it is on precipitation.

It is often believed that groundwater is located in voids. This happens, but mostly groundwater is a mixture of sand, gravel, other minerals and a lot of water.

It was said where groundwater comes from and how it moves, but it was not said where it goes. And they either disappear even deeper underground, or pour out to the surface in the form of springs, springs, geysers, springs and other similar phenomena. So, for example, the Dnieper originates from underground somewhere in Belarus. Near Cape Aya (Crimea, not far from Sevastopol), there is a source of fresh water flowing into the sea. I haven’t seen it myself (it’s kept secret:), but a diver told me: you dive with a bottle, open it underwater with the neck down, fresh water fills in.

In addition to natural types of groundwater outlets, there are also artificial ones. These are wells. And such an interesting phenomenon as artesian water is associated with wells. A long time ago, in France, in Artez, they drilled a well in search of water. And water began to flow from the well like a fountain. That is, artesian waters are waters that rise from the ground without the help of pumps. There are few such cases, most often there are free-flow wells.

So, like everything in nature, groundwater has a beginning, a change and an end - it falls underground with rain, travels underground from layer to layer and eventually pours out to the surface.

The underground water cycle, so to speak :)

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 the upper layer of the 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 spring.

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 the 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.

(to a depth of 12-16 km) in liquid, solid and vapor states. The bulk of them are formed due to seepage from the surface of rain, melt and river waters. Groundwater is constantly moving in both vertical and horizontal directions. The depth of their occurrence, direction and intensity of movement depend on the water permeability of the rocks. Permeable rocks include pebbles, sands, and gravel. Waterproof (waterproof), practically impervious to water - clay, dense without cracks, frozen soils. The layer of rock that contains water is called an aquifer.

According to the conditions of occurrence, groundwater is divided into three types: those located in the uppermost soil layer; , lying on the first permanent waterproof layer from the surface; interstratal, located between two impermeable layers. Groundwater is fed by seeped sediments, waters, lakes,. The groundwater level fluctuates according to the seasons of the year and is different in different zones. Thus, it practically coincides with the surface and is located at a depth of 60-100 m. They are distributed almost everywhere, do not have pressure, and move slowly (in coarse sand, for example, at a speed of 1.5-2.0 m per day). The chemical composition of groundwater varies and depends on the solubility of adjacent rocks. Based on their chemical composition, they distinguish between fresh (up to 1 g of salts per 1 liter of water) and mineralized (up to 50 g of salts per 1 liter of water) groundwater. Natural outlets of groundwater on the earth's surface are called sources (springs, springs). They are usually formed in low places where aquifers cross the earth's surface. Springs can be cold (with no higher than 20°C), warm (from 20 to 37°C) and hot or thermal (over 37°C). Periodically gushing hot springs are called geysers. They are located in areas of recent or modern (,). The waters of the springs contain a variety of chemical elements and can be carbonic, alkaline, salt, etc. Many of them have medicinal value.

Groundwater replenishes wells, rivers, lakes, ; dissolve various substances in rocks and transport them; cause landslides. They provide plants with moisture and the population with drinking water. The springs provide the purest water. Water vapor and hot water from geysers are used to heat buildings, greenhouses and power plants.

Groundwater reserves are very large - 1.7%, but are renewed extremely slowly, and this must be taken into account when using them. No less important is the protection of groundwater from pollution.

Underground springs

Water intake structures

Definitions:

Water intake structures(water intake) - a complex of hydraulic structures and pumping stations that ensure water intake from the source, preliminary treatment and supply, in accordance with consumer requirements for its uninterrupted flow, flow and pressure.

Water intake(water intake device) - a structure with the help of which water is taken from a water supply source and protected from fauna and flora objects entering the transported stream.

Water intake- the process of withdrawing water from a water supply source.

Deep water extraction- the process of selecting water from the lower layers of a water supply source.

Source of water supply- a watercourse or body of water used for water supply.

Place of water intake- a section of a water supply source within which the water taken by the water intake affects the movement of sediment, debris, sludge, plankton, as well as the direction of currents excited by other factors.

Local water source conditions- a set of topographic, geological, meteorological, hydrological, hydromorphological, hydrothermal, hydrobiological and other factors of a selected or specified source area. Since these factors are interrelated, local conditions usually
individual for each selected area of ​​the water supply source.

Density stratification- change in water density along the depth of a watercourse or reservoir. It can arise due to a difference in temperature or salinity of water between the surface and bottom layers, as well as due to the influx of masses of water with a high sediment content.

Lecture 1.

Types of water supply sources

Surface sources

Watercourses – rivers, canals;

Reservoirs - lakes, seas, oceans

Underground springs

Groundwater is distinguished: for high water, groundwater, artesian water, and mine water.

For the northern regions of the country, these waters are distinguished: supra-permafrost, inter-permafrost and sub-permafrost.

Groundwater reserves are divided into natural and operational.

Natural reserves– these are the volumes of water contained in the pores and cracks of rocks (static and elastic reserves) and the flow rates of water flowing through the considered section (section) of the aquifer (dynamic reserves).

Operating reserves determine the practical possibilities of groundwater extraction and characterize the amount of water that can be obtained from the reservoir using water intake structures that are rational in technical and economic terms under a given operating mode and water quality that meets the requirements of consumers during the estimated period of water consumption

Topic: Groundwater conditions.

Types of water intakes. Conditions for their use

The science of hydrogeology studies groundwater.

According to the conditions of occurrence (Fig. 1), two main types of groundwater are distinguished - free-flow and pressure. The horizons of free-flowing waters do not have a continuous impermeable cover. In such horizons, a free water level is established, the depth of which corresponds to the surface of the aquifer.

Waters of the first continuous aquifer from the surface

They are called ground. Lens-shaped accumulations of water on aquitards or low-permeable layers with local distribution form a perch, which is located above groundwater.

Groundwater is, as a rule. the waters are free-flowing, although in some areas they may acquire local pressure; They usually lie at shallow depths and are therefore exposed to hydrometeorological factors. Depending on the season,

precipitation and temperature change both the level of groundwater and its chemical composition. Groundwater recharge occurs through the infiltration of atmospheric precipitation and river water, and in some cases due to the influx of pressure water from underlying horizons. Due to their shallow location and lack of impervious coverings, groundwater can easily become contaminated. Conditions

The occurrence of these waters is very diverse.

Pressure water is contained between waterproof layers. In a borehole that has penetrated a pressure aquifer, water rises above the roof of this horizon. If the pressure (piezometric) level is located above the ground surface, then the well flows. Therefore, to obtain self-flowing water, wells must be drilled in areas with low relief. A permeable formation bounded by two aquitards may not be filled with water. In this case, semi-pressure or non-pressure interstratal waters are formed. Pressure waters are often called artesian, regardless of whether these waters flow to

Rice. 1 Diagram of groundwater conditions

An aquifer is confined if it has a recharge area located at higher elevations than the impermeable roof of this horizon.

When water is pumped out of a well, a depression funnel is formed around it. In non-pressurized waters, this funnel reflects a decrease in the water level around the well, draining part of the aquifer. In the pressure horizon, depression of the piezometric surface is formed - a decrease in pressure in a certain zone around the well. Artesian waters usually lie at more or less considerable depth. They are isolated from the surface by waterproof layers and are therefore less susceptible to pollution than groundwater. When assessing the possibility of using groundwater, their natural operational reserves are determined. Natural groundwater reserves mean the amount of groundwater located in aquifers that are not disturbed by the operation of water intake structures; under operational conditions, their consumption, which can be obtained at the field with the help of water intake structures in a technical and economic ratio under a given operating mode with water quality that satisfies the requirements of consumers during the estimated time of consumption. . They form part of natural reserves. When designing water intake structures, operational reserves of groundwater are calculated based on the results of detailed hydrogeological work carried out at the field.

During the exploitation of an aquifer, the natural regime and balance of groundwater is disrupted, as a result of which a zone of low pressure appears in the area of ​​water extraction, and thus favorable conditions are created for the involvement of additional resources in this exploited aquifer: the flow of water from adjacent aquifers separated by low-permeable layers, infiltration of atmospheric precipitation, filtration from surface streams and reservoirs, artificial regulation of water regime, etc. Depending on the degree of exploration of operational reserves, the complexity of hydrogeological and hydrochemical conditions, the uniformity of filtration properties of water-bearing rocks determines the category of groundwater.

Topic: Types of groundwater intakes. Conditions for their use. Water intake using wells

The choice of the type and layout of water intake structures is made based on the geological, hydrogeological and sanitary conditions of the area, as well as technical and economic considerations. Groundwater intakes consist of both individual structures (captage) for obtaining groundwater, and their system

:(water intakes). One capture structure can also be called a water intake. Water intake wells and shaft wells are widely used in the exploitation of both free-flow and pressure groundwater. Mine wells are used more often when consumption volumes are small and groundwater depth is 20-30 m. Effective use of water wells is possible when the depth of the base of the aquifer is more than 8-10 m and when its thickness is 1-2 m. The efficiency of their use increases with the depth of the aquifer water; When aquifers occur in layers, when one or more of them are sources of water supply, wells become indispensable.

Horizontal water intakes can be used in shallow aquifers of small thickness. Often their use makes it possible to achieve a higher effect in water intake than the use of vertical water intakes. Horizontal water intakes in the form of drainage pipes and galleries, used to capture groundwater, are laid in dug ditches and located at a depth of no more than 5-8 m. Horizontal radial water intakes are drilled from a central shaft - chamber and are more often used to capture groundwater, and more recently time - and to capture pressure water at a depth of 20-30 m. Horizontal water intakes in the form of adits and kariz are installed at water depths of up to 20 m, and sometimes more. Kariz are an ancient method of capturing groundwater. Currently, they are not being built, but previously completed ones are being operated and repaired (Transcaucasia and southern Central Asia). Capture structures are designed to receive water from ascending and descending sources (springs, springs). Depending on the conditions of the exit to the surface of the earth from the aquifer, catchments can have a different design: in the form of drainage pipes with collections from a well to a chamber, one capture chamber, and sometimes in the form of a shaft with a drain pipe. Such structures are relatively rare in Russia.

Abstraction of groundwater using boreholes is... the most common method in water supply practice, as it is distinguished by its versatility and technical excellence. It is used in a wide range of groundwater depths. Water from water intakes is transported through collection pipelines to reservoirs or to main water pipelines or to on-site consumer networks. Water pipelines can also be combined with the on-site water supply network; According to the hydraulic mode, they can be pressure, gravity and gravity-pressure. Siphon water intake schemes use a special type of water conduits - siphon prefabricated ones. The layout of prefabricated water pipelines is very diverse in plan (linear, dead-end, ring, paired), as they depend on the location of water intakes, collection tanks, the category of reliability of water supply, etc. The most common are linear schemes of water pipelines, which are designed in one or several threads (Fig. 2). Circular (Fig. 3. and park schemes Fig. 4) arrangements of prefabricated water conduits are possible.

Rice. .2. Schemes of linear (dead-end) prefabricated water pipelines

The choice of scheme is made on the basis of a techno-economic comparison of options. With a large length of collecting water lines and a large number of wells, it is sometimes more expedient to connect water lines to several collecting tanks (depending on the location of water consumers in relation to the water intake site).

The scheme for transporting water depends on the method of its production. Pressure prefabricated water conduits are most widespread, which is caused by the use of borehole systems equipped with submersible pumps. Gravity-flow systems of prefabricated water pipelines are used for collecting water from captages, self-flowing wells, as well as from wells equipped with pumping units or airlifts.

The advantage of these systems is the possibility of using free-flow pipes. When supplying water from water collection structures to a gravity network, the operation of each pumping station does not depend on the operation of others and can be adjusted without taking into account their interaction.

Rice. .3. Schemes of ring prefabricated water pipelines.

Rice. .4. Schemes of paired prefabricated water pipelines

The water intake well, in accordance with the requirements of drilling and geology (Fig. 5), has a telescopic design. The lowest part of the well serves as a settling tank. Above the sump there is a water intake part of the well - a filter through which water from the aquifer enters its working area. Above the water intake part of the well there are columns of production and casing pipes, which, on the one hand, keep the walls of the well from collapsing, and on the other, serve to place water-lifting pipes and pumps in them. Above the production string there is a conductor, which sets the direction of the pipe passing through it during drilling. A cement or clay lock is placed around the conductor, protecting the aquifer from contaminants entering from the surface through the annulus of the casing pipes. The upper part of the wells is called the mouth or head. The head, depending on the depth, can be located both in the pavilion and in the well, where: mechanical and electrical equipment is located. The organization of boreholes depends on the type of aquifers, their depth, the type of rocks being drilled, their aggressiveness, the diameter of the well and the drilling method.

Rice. .5. Water well.

In the practice of constructing water wells, the following drilling methods have become widespread: rotary with direct circulation, rotary with reverse circulation, rotary with air blowing, percussion-rope, jet-turbine and combined.

The shock-rope method is used when drilling wells to a depth of up to 150 m in loose and rocky formations and the initial diameter of the well is more than 500 mm. The walls of the wells are secured with pipes continuously as the face deepens.

Based on the nature of the deepening, rotary drilling is divided into circular and continuous face drilling. Drilling with an annular face is called core drilling, while drilling with a continuous face is called rotary. The core method is used in rock formations with a well diameter of up to 150-200 mm and a drilling depth of up to 150 m. For drilling wells of large diameters and depths of more than 500-1000 m, the reactive turbine method is recommended.

The combined method (percussion-rope and rotary) is used for drilling wells more than 150 m deep in free-flow and low-pressure aquifers represented by loose sediments. The method of washing depends on the type of soil being passed through. Water and clay solutions are used as washing solutions.

When choosing a drilling method, not only the manufacturability of the method and the rate of penetration are taken into account, but also the provision of conditions that guarantee minimal deformation of rocks in the bottomhole zone.

The well must ensure the durability and protection of the production aquifer from penetration from the surface of the earth and the influx of water from overlying aquifers. The simplest diagram of the drilling rig design is shown in Fig. 6. The well is secured with casing pipes 1. The pipe is lowered to the top of the aquifer boundary 6. A pipe of smaller diameter 2 is lowered into the casing, which is buried in the underlying waterproof layer. Then filter 3 is lowered into pipe 2 using a rod with a special lock 4, after which pipe 2 is removed, the gap 5 between the walls of the filter and casing pipes is sealed. With a large well depth (depending on the drilling method), it is not possible to reach the required level with a casing pipe of the same diameter. In this case, another pipe of smaller diameter D2 is lowered into a casing pipe with a diameter of D1 (Fig. 7a), which has reached a depth of h1, which is buried to a depth of h2. The depth of the pipe is determined based on the resistance of the rocks to its advancement and technological considerations. The path traveled by a string of casing pipes of the same diameter is called the exit of the string. Further deepening of the well is achieved using casing pipes of smaller diameter D 3, etc. The difference between the diameters of the previous and subsequent casing strings must be at least 50 mm. The yield of the column depends on the particle size distribution of the rock and the drilling method. With the shock-rope method it is 30-50 m and only for

Rice. 6. Diagram of a borehole at small and large depths

stable rocks can reach 70-100 m. With rotary drilling, the yield increases to 300-500 m, which significantly simplifies the well design, reduces pipe consumption and speeds up the drilling process. When a well is telescopically constructed, in order to save casing pipes, the internal pipe columns are trimmed (see Fig. 7.6). The upper edge of the casing pipe remaining in the well must be at least 3 m above the shoe of the previous string. The annular gap between the remaining part of the string of cut pipes and the previous string of casing pipes is cemented or sealed, arranging an oil seal.

When a well passes through two aquifers, the upper one, which is not exploited, must be covered with a blind column, and it must be buried in the aquitard. Well designs are very diverse.

For fastening wells, steel coupling and electric-welded casing pipes are used; for wells up to 250 mm deep, sometimes high-grade asbestos-cement pipes are used.

Various types of water lifting equipment are used to lift water from wells. Pumping units of the ECV type are used for equipping wells with a depth of 10-700 m or more. They can work in deviated wells under a variety of hydrogeological conditions. Pumping units with a transmission shaft are used for wells up to 120 m deep; they can only operate in vertical wells. Water with an estimated dynamic damage of no more than 5 m from the surface of the earth can be collected by horizontal pumps. To lift water from wells, airlifts are used, which allow lifting water from curved wells, as well as water containing mechanical impurities in quantities exceeding the limits established for other types of pumps.

Pavilions are built above the mouth of water intake wells to house the well head, electric motor, horizontal centrifugal pump, starting and control equipment and automation devices. In addition, they contain parts of a pressure pipeline equipped with gates, a check valve, a plunger, and a sampling valve. Each well is equipped with a flow meter.

Pavilions over wells can be of underground or above-ground type. Underground pavilions are usually built in dry soils. To reduce construction volumes, they are made with two chambers in the form of water wells.

If water intake wells are located in places flooded by flood waters of floodplain rivers, then the pavilion is built on fill or under the protection of embankment dams with a height exceeding the maximum flood horizon. Filters largely determine the reliability of the water intake structure, since they must ensure free access of water into the well, stable operation of the wells for a long time, protect against sanding with minimal hydraulic losses, and in case of clogging of its surface, allow for the possibility of carrying out restoration measures. In addition, they must be resistant to chemical and electrochemical corrosion.

The main pressure losses in the filter occur on the water receiving surface (frame) and gravel packing (water-bearing rock). Filters can be classified as shown in Fig. 8.

Rice. .8. Classification of water well filters

The filter consists of a working (water receiving) part, above-filter pipes and a settling tank. The length of the above-filter pipes depends on the well design. If the filter is located on a column, then the above-filter pipes are its continuation. With a smaller diameter, the above-filter pipes enter the production string at least 3 m at a well depth of up to 50 m and at least 5 m at a greater depth. In the gap formed between them, a seal made of rubber, hemp, cement, etc. is installed. Under certain conditions, the role of the seal is played by a layer of gravel filled between the production casing and the filter. The height of settling tanks in filters, as a rule, is assumed to be 0.5-2 m.

The most widely used are particle filters, which include frame filters and filters with an additional water receiving surface. In these designs, the effect of preventing sanding is achieved by selecting the size of the hole in the filter housing relative to the particle size of the aquifer or gravel. A filter with a gravel deflector is characterized by the presence of elements of the water receiving surface that prevent direct application of aquifers or gravel particles to the filter.

In gravity filters, wide water intake holes are installed in which the soil is kept from being carried away under the influence of gravity.

The main elements of the filter are the supporting frame and the water receiving surface. The frame provides the necessary mechanical strength and serves as a supporting structure for the filter surface. SNiP “Water supply. External networks and structures" recommends the following types of frames: rod, tubular with round and slotted perforations, stamped from steel sheet. Wire winding, stamped sheet, stamped sheet with one- or two-layer sand-gravel coating, square and braided mesh are used as a filter surface. When collecting small quantities of water, filters made of porous concrete (so-called porous) can be used.

The filter designs are shown in Fig. .9.

Rice. 9. Basic design diagrams of water well filters

Table 1

Topic: Calculation of water wells

Water wells are used to collect both pressure and non-pressure groundwater (Fig. 10). There are two types of wells: perfect and imperfect. By perfect we mean a well that penetrates the aquifer to the underlying aquifer. If the well ends in the thickness of the aquifer, then it is called imperfect. There are two types of opening imperfections: by the degree of opening of the horizon, which depends on the ratio of the length of the filter and the thickness of the formation, and by the nature of the opening, which depends on the filter structures installed in the formation. The main design task is to select a rational type and layout of the well system, i.e. determining the optimal number of wells, the distances between them, their relative location on the ground, filter designs, diameters and routing of pipelines, characteristics of pumping equipment, taking into account a possible decrease in the water level in the wells. These problems are solved on the basis of hydrogeological calculations to determine the flow rate of wells and the decrease in water level during operation, assessing the mutual influence of individual wells when they work together. At the same time as solving these issues, the layout of water intake wells, their number and type are clarified. When carrying out hydrogeological calculations, the flow rate corresponding to the specified water consumption is taken as the initial value, or

Rice. 10. Types of wells

1 - filter; 2 - well; 3 - waterproof layer (roof); 4 - pressure plane;

5- aquifer; 6- waterproof; 7 - depression curve; 8 - static water level; 9 - water level during pumping

the maximum flow rate that can be obtained. In both cases, calculations establish

dimensions of water intake structures (depth, diameter), number, location and flow rate of wells

for a given duration of operation and maximum permissible drops in water level.

Based on the variant hydrogeological calculations of the schemes under consideration, we select

optimal. In all options, the calculated level decreases are compared with the permissible ones.

If the calculated level decreases beyond the permissible level, the well production cannot be ensured. In this case, it is necessary to increase the number of wells or distribute them over a small area. When the level drops below the permissible level, the well flow rate can be increased. If an increase in flow rate is not required, then the number of wells should be reduced or reduced

the distance between them. You can also vary the layout of water pipelines. Hydrogeological

calculations of water intake structures are carried out on the basis of filtration laws. Let us consider the general calculated dependencies for determining the water flow of a water intake structure. Well production

in aquifers can be found according to the following relationships:

pressure

Q = 2p k m S extra/R

free-flow

Q = p kmS extra (2h e - S extra) / R

Where k- water conductivity of the exploited formation (here/s is the filtration coefficient; m is the thickness of the formation); S additional - maximum permissible drop in groundwater level; h e - natural power of ground flow; R= R o + bx - filtration resistance, depending on hydrogeological conditions and type of water intake structure (here R o - hydraulic resistance R at the well location; x - additional resistance, taking into account the filtration imperfection of the well; b = Q o /Q - the ratio of the flow rate of the well in question Q o to the total water intake flow Q). .

Quantities R, R o and x can only be determined with varying degrees of detail

hydrogeological situation. When constructing calculation schemes, it is assumed that the aquifer

layer (system, complex of aquifers) both in natural conditions and in conditions

operation of water intakes is a single physical area with

certain external boundaries. Fundamental works are devoted to determining these conditions

F.M. Bochever and N.N. Verigana. Conditions include geological structure, structure and properties

aquifers, as well as sources of groundwater replenishment. The choice of one or another scheme is carried out on the basis of hydrogeological data obtained as a result of surveys, or based on an analogue of nearby wells. In accordance with the diagram, one or another calculated dependence is used to calculate resistances. In table 5.2 shows some calculated dependencies for determining hydraulic resistance during the operation of water intakes of various types near perfect rivers under conditions of steady filtration. Perfect rivers include rivers of considerable width without silty or clogged material that prevents the filtration of river water into the aquifer. Artesian basins are characterized by a layered structure of water layers. Well-permeable aquifers alternate with water-resistant and weakly permeable layers. For these basins, the following design schemes are considered: isolated aquifers of unlimited area and layered aquifers in section. Isolated unconfined formations are characterized by the absence of external sources of groundwater supply. During the operation of water intake structures, the groundwater level continuously decreases. The operation of such water intakes is accompanied by the formation of depression craters that cover vast areas. Under these conditions, the possible impact of the designed water intake on existing water intake structures should be taken into account. Basic calculation dependencies for the distribution of hydraulic resistance R0 when operating water intakes in isolated unbounded layers are given in table. .3. These dependencies include the conditional radius of influence of the well g in = , Where A - co uh coefficient of piezoelectric conductivity of the formation, characterizing the rate of redistribution of groundwater pressure during unsteady movement (here k is the filtration coefficient determined experimentally; m is the thickness of the formation; t is the duration of the decrease in groundwater; m is the water yield coefficient of the pressure formation)

In layered aquifers, groundwater reserves are formed under the influence

flow of groundwater into the exploited horizon from neighboring feeding strata

through low-permeability separate layers in the roof or bottom of the horizon. Mode

The operation of these water intakes is generally unsteady. However, with large stocks

water in the feeding formations and intensive flow of water into the exploited formation below

levels at the water intake may stabilize. Calculated dependence to determine

hydraulic resistance R o in two-layer layers is given in table. 4. It refers to the case when the top layer has very weak permeability (k o< k), содержит воды, имеющие свободную поверхность, и обладает значительной водоотдачей (m>m*). The lower exploited layer is composed of highly permeable rocks. This pattern is typical for artesian aquifers located at shallow depths. Similar dependencies exist for other conditions of groundwater occurrence.

When calculating water intakes, it is necessary to take into account the additional filtration resistance x, due to the degree of opening of the well aquifer. The numerical value of the coefficient x depends on the parameters m/r o and l f/m, Where m- aquifer thickness; r o - well radius; l f – filter length. For non-pressure waters m=h e - S o/ 2 . ; l f =; l fn -S o / 2, here h e - initial power of free-flow flow ; S o – lowering the water level in the well; l fn– total length of the unflooded filter. Numerical values ​​of x are given in Table 5. Permissible drop in water in the well S extra determined based on experimental pumping data. The approximate permissible drop in water level can be determined:

free-flow

S add= (0.5÷0.7) h e - D h us - D h f

pressure

S add = N e- [(0.3÷057)]m+ D N us - D N f

Where Not And h e- pressure above the base of the horizon (in pressure strata) and the initial depth of water to the aquitard (in unconfined horizons);

D h us D N us- maximum immersion depth of pumps (with its lower edge under the dynamic level);

D h f, D N f– pressure loss at the well inlet, m– thickness of the aquifer.

COMPREHENSIVE CALCULATIONS OF GROUNDWATER WATER INJECTIONS

Water intake wells, interconnected by prefabricated water conduits, represent a single hydraulic system. During the operation of such systems, the relationship between changes in the flow rate of wells (and water intake in general) with changes in the hydrodynamic regime of groundwater, as well as the hydraulic parameters of individual structures, is clearly visible. Therefore, already at the project development stage, the performance of the system should be assessed. Such an assessment is made on the basis of comprehensive calculations of groundwater intakes. The main task of a comprehensive calculation of groundwater intakes is to determine the true values ​​of well flow rates and decreases in the water level in them, as well as flow rates and pressure losses in collecting water pipelines and operating parameters of water-lifting equipment. Therefore, such calculations should be carried out under different design modes and for different periods of operation of water intakes (i.e., taking into account seasonal fluctuations in levels and depletion of groundwater reserves, colmatage and failure of wells, disconnection of individual lines of collecting water pipelines, etc.) and Based on this, schedule the implementation of activities aimed at maintaining stable operation of the system. The starting material for performing calculations of water intakes are: a) hydrogeological design diagram for the location of water intake and infiltration structures; b) design scheme for collecting water from wells; c) high-altitude diagram of water supply to the consumer.

Graphic-analytical methods for hydraulic calculation of operating modes of single wells.

When withdrawing water from a well (Fig. 11), pump pressure H is spent on overcoming the geometric height of water rise z, lowering the level S and pressure losses in the water pipeline D h from the well to the water supply point. In this case, the pump installed in the well develops a pressure equal to:

H = (Ср - Сст. hor.) +S+ D hвр.

Where N - total height of water rise from the well; v p, - water level mark in the tank; V st. mountains - mark of the static groundwater level; S- lowering the level in the well; D h in - pressure losses in the water pipeline from the well to the reservoir, including pressure losses in water-lifting pipes.

The difference in elevations (Ñ r - Ñ st.horizon) is the geometric height of the rise of water from the well. If these marks do not change, then (Ñ p - Ñ st.hor.) = const= z

On the other hand, the pump develops pressure in accordance with its operating characteristic H-Q, which in the range of optimal efficiency values ​​can be approximated by an equation of the form: H = A-BQ 2

Where A And IN - characteristics of the H-Q pump.

Rns.11. Water supply diagram from a well

1- filter; 2 - pump

Rice. 12. Graphic-analytical method for calculating the well-pump-water pipeline-reservoir system"

Substituting expression (4) into formula (3) and taking into account the dependence S = ¦(Q) and D h= ¦(Q) gives the expression

Z + (R+x) + l AQ 2 = A-BQ 2

where k is the filtration coefficient; T- thickness of host rocks ( k m- coefficient

water conductivity of rocks); R - formation filtration resistance; x - filtration

well filter resistance; l- length of the water riser pipe from the pump to the connection point

wells to the reservoir and A, is the resistivity of the water pipeline.

In relation to single wells, equation (5) can be solved graphically. To do this, the H-Q coordinates should be positioned so that the point H = 0 is located at the v level of the mountains. Then the line v = const (on the graph (Fig. 12) will determine the geometric height of water rise from the well, and the line 1 - characteristics of the well SQ (the characteristics of the well can be constructed both from experimental data and on the basis of calculations). Finally, by specifying the hydraulic resistance, the characteristics of the water pipeline h-Q are plotted (curve 2). When adding the characteristics S-Q and D h -Q, the combined characteristic (curve 3) wells of a water pipeline and a reservoir, which is a graph of the dependence of the total height of water rise on the flow rate of the well.

Rice. 13. Graphical method for solving the problem of well flow control

The graph (Fig. 12) also shows the characteristic ( H-Q)(curve 4) pump that is supposed to be installed in the well. Its intersection with the curve 3 gives the operating point of the pump with coordinates N r and Q r(Where Q p-actual pump flow and N r - pressure developed by the pump with such a water supply). At the same time, the values ​​of S in the well and D h in the water conduit were also determined. Often, from the available range it is not possible to select a pump whose operating point exactly corresponds to the required Q or H wells. Therefore, in practice, pumps are selected with a certain margin of pressure and their supply is regulated. Such regulation is usually carried out using valves installed on the pressure line; less often - by changing the number of pump impellers.

In the case when the pump supply is regulated by installing a throttle on the pressure line connecting the well to the water pipeline, the efficiency of the installation sharply decreases and amounts to

h= h y

here h is the efficiency of the installation, taken according to the H-Q graph at a given pump Q; H n - pump pressure, based on supply Q minus pressure losses D h in the water pipeline; z p- throttling value.

Therefore, due to its uneconomical nature, this method of regulation cannot be recommended for a long period, especially in the case when the values z p great ( z p>D N n), where D N n - pressure developed by one pump impeller. At z > D N n the flow of pumping units should be adjusted by changing the number of impellers. The number of wheels that need to be removed from the pump is determined by the expression n = z And / D N r with rounding P to the nearest smallest integer value. In case if z > D N n, then, simultaneously with the change in the number of impellers, a throttle is installed on the pressure line to ensure a given pump flow. The magnitude of the throttled pressure is

Z n > Z n - n D N n

Let the condition require that water be supplied to the reservoir in the amount of Qt, while

Qt< Q . Этому расходу на совмещенном графике рис.12 соответствует точка В с координатами

Qt and Ht. The actual pump pressure when supplying water in quantity Qt is equal to H t1 (H t1 > H t).

Consequently, the throttled pressure is zt = H| - Ht. At the intersection of the perpendicular,

restored from point B to the x-axis, with lines 1 and 3 containing the desired values ​​of all lines

variable zn", D h o and 5 t when water is supplied in the amount of Q t. If any of the components changes

dependence (.5) the operating point of the pump shifts according to the Q-H characteristic. So, for example, the depletion of groundwater reserves leads to an increase in the geometric height of water rise from wells, i.e. to an increase in pump pressure H and, accordingly, a decrease in well flow rate Q. A similar picture is observed with an increase in the hydraulic resistance of the well filter caused by colmatage. Time Тз during which conditions S are not violated From> can be considered a period of stable operation of the well. However, in practice, this time, as a rule, turns out to be less than the estimated life of the wells. Let us assume (Fig. 13) that the well characteristic (line]) was determined for the period of its construction, and during the operation of the well, the hydraulic resistance of the filter increased, and the characteristic began to be determined by line 2. As a result of these changes, the operating point of the pump will shift from point B to point B". In this case (see Fig. 13) the decrease in the water level in the well will be 5" > 5, and its flow rate will decrease by the amount DQ. In Fig. 13, for clarity of the graphical construction, the H-Q characteristic of the pump is replaced by the so-called throttle characteristic, obtained by subtracting the pressure losses in the water pipeline D h in from the ordinates H. To ensure the required supply of the pumping unit in the amount of Qt, the pressure losses at the throttle should be reduced by the value zn and they should be zн = zн - (S" - S). In this case (as can be seen from Fig. 13), the decrease in the water level in the well increases. Therefore, this method of regulating the supply can only be used for a certain period of operation, until the decrease in the well is less than S (or while the value ";>o). In Fig. 5.13, point D corresponds to the condition when at () = f, (r > 0), and 5 = 5 op. With r"n unchanged, a further increase in resistance will cause a decrease in feed installations. At the same time, if r "a is reduced to values ​​at which the water supply from the well would be (), then there will be an increase in the decrease in water level I in the well and 5 will exceed 5. Consequently, the characteristic of the well, represented by curve 2, corresponds to the conditions when the filter is extremely clogged and further operation of the installation without implementing a set of measures to restore the well's flow rate is impossible. By regenerating the well filter, it is possible to reduce the hydraulic resistance to values ​​close to the initial one. Then, with a throttled pressure zn", the installation flow will be Qn > Qt, and as the resistance increases, the flow water will decrease and only when the maximum clogging of the well filter is reached will it be equal to Qt. The introduction of artificial groundwater recharge systems (AGR) causes an increase in the groundwater level, which, in turn, leads to an increase in the flow of the pump installed in the well. At the same time, to ensure a given increase in flow, it is also necessary to regulate the operation of the pump or replace it. Let us assume that the IPPV installation was put into operation at the time t = Ts (when the well filter is extremely clogged) and ensured an increase in the level by the amount of DS. Then, based on hydrogeological calculations, it is possible to increase water intake, bringing it to a value Qg equal to

Qr=Qt+2pkmDS. /(R+x) (.6)

where k is the filtration resistance of the aquifer under the action of the water intake

wells; x - additional resistance to imperfection |well at time Ts

In Fig. 14, the value of Q is the abscissa of point C, which lies at the intersection of the well characteristic (line 2) and line a - b corresponding S additional + DS, where DS = Q b, R b./ 2pkm, R 6 - [filtration resistance of the aquifer under action

Rice. 14. Calculation of the increase in well production rate during artificial replenishment

groundwater (IGW)

will have

supply of water in quantity from any n-th well at the given level is

Rice. 5.17. Scheme of connecting wells of a linear series to a collecting water pipeline.

After that

In addition, pump pressures are determined

rezv operation. For this purpose, calculations of Water Intakes are carried out in the following order.

Subject. . Mine wells. Horizontal water intakes

Rice. .22. Shaft well diagram

Rie. .23 Construction of a shaft well made of prefabricated reinforced concrete rings

Horizontal water intakes

Modern horizontal water intakes, as a rule, are a drainage trench or a drainage gallery equipped with appropriate openings with a sand-gravel filter for receiving water. The granulometric composition of the individual layers of the reverse filter is determined by calculation. Water is drained to the location of the nodose intake devices through trays located in the lower part. For inspection, ventilation and repairs during operation, the water intake is equipped with inspection wells.

When withdrawing small quantities of water for small consumers for temporary water supply, as well as when the depth of groundwater is 2-3 m from the surface of the earth, trench water intakes are used. Stone-gravel water intake (Fig. 5. 24, a) is carried out in a trench, laying filter materials, the size of which increases towards the middle of the trench. The ratio of the diameters of particles of adjacent layers of coating and particles of the upper layer is selected for coating filters of well water intakes.

Rice. Trench water intakes

Rice. .25. Oval and rectangular water intake gallery

Rice. .26 Rectangular water intake adit

in pressure flow

is. 27. Scheme for calculating horizontal water intake

Hydraulic resistance R is found using the formula

C= x o/ l (x o- distance from the river to the water intake; 1 - half the length of the water intake).

Additional resistance x can be found using the formula.

Where r o- drain radius; With - deepening the drain below the groundwater level.

For non-pressure flows, the thickness of the pressure layer m=h avg, Where h avg- average power of ground flow during water intake operation ( h avg= 0.7 ¸0.8)

For rectangular drains and channels r o = 0,5 (b 1+ 0,5 b 2), Where b 1- deepening the drain below the groundwater level; b 2- drain width

In the case of a river that is perfect in terms of filtration (Fig. 28). hydraulic resistance R determined by the formula

R =ln)