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

Hundreds of millions of liters of water flow from artesian basins to the surface every day.

The springs are not limited to surface waters. Recently, scientists have discovered hot springs in the oceans at a depth of about 2.5 km, mainly along mid-ocean ridges. The hot water (over 300 degrees Celsius) from these springs is rich in minerals and sulfur, creating a unique ecosystem where unusual and exotic underwater life 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 voids of limestones, dolomites filled with underground waters.

Where the aquifer from below rests against impermeable rocks, water moves along horizontal planes, penetrating into the rocks, washing out cavities in them. Thus, the resulting flow comes to the surface in the form of a source.

These processes last from tens to hundreds of thousands of years.

Water consumption from springs

The amount of water from springs depends on many factors, including the size of the cavities in the rocks, the water pressure in the aquifer, the amount of spring runoff, and the amount of regular rainfall.

Human activities can also affect the volume of water from a spring. in an area, if heavily withdrawn, can reduce the pressure in the aquifer, lowering the water level in the aquifer system, and ultimately reducing the flow from the source.

Most people probably think that the spring water comes from an indoor pool. In fact, water that is in motion under the influence of geological, hydrological or human factors can create pressure and pour out in the form of a source.

Spring water may have color

If red or brown water flows out of the source, this indicates a high iron content. Water, in contact with various permeable rocks, is enriched with minerals of natural origin present in the rocks, thanks to the ancient volcanic activity in this district.

In some areas, surface waters contain natural tannic acids coming from organic subsoil layers, and the color of the substances may appear in the springs.

If water enters an aquifer near a spring, it may, before reaching the aquifer, flow out of that source.

The release of strongly colored water from springs may indicate that water from large channels enters the aquifer without sufficient filtration.

Spring water quality

The quality of water in a local groundwater system can often be determined from spring water.

The quality of water from a source can vary greatly depending on factors such as the quality of the water replenishing the aquifer and the type of rock with which the groundwater is in contact.

The speed of water movement in aquifers affects the amount of dissolved minerals. The lower the speed, the more time the water is in contact with the minerals and carries away with it.

Water quality can also change as a result of mixing fresh water with ancient sea ​​water, "sealed in pockets" in the aquifer, or with sea water near the coast.

Seeing the crystal-clear cold water flowing from the spring, it is hard not to fall for it. But be careful.

Water, passing through permeable layers, is filtered from debris and dirt. If the water is underground long enough, the disadvantage sunlight causes the death of most algae and aquatic plants. However, viruses and bacteria are not killed underground and dissolved agricultural or industrial pollutants are not removed.

thermal springs

Many hot springs are found in regions of recent volcanic activity and are fed by water heated by contact with hot rocks at depth.

There are thermal springs in places where volcanic activity has long died out. With increasing depth, the temperature of the rocks increases, in which water slowly moves and heats up.

Heated water from the depth finds paths with low resistance and quickly comes to the surface. The water does not have time to cool down and a thermal spring is formed.

This forms the upper aquifer containing groundwater. Deeper aquifers are formed mainly by seepage from surface water (Figure 18).

Groundwater is divided into:

1) according to the conditions of occurrence in the earth's crust - on soil, interstratal, fissure and karst,

2) according to hydraulic characteristics - into non-pressure and pressure ones;

3) by temperature - into cold (with a temperature of less than 20 ° C), warm (20-40 ° C) and hot (at a temperature of more than 40 ° C).

Groundwater is also divided by chemical and gas composition, origin, etc.

Ground the waters of the uppermost aquifer lying on the first aquiclude are called. These waters are extremely important for road construction, since the depth of their occurrence largely determines the height of the elevation of the subgrade of roads and whole line other measures aimed at giving road structures the required stability.

The type of groundwater is perch. This is usually called a temporary accumulation of groundwater at a shallow depth from the surface. Verkhovodka is formed due to the poor water permeability of rocks during periods of abundant waterlogging, when the seeped water does not have time to descend to the groundwater level.

Actually underground, or interstratal, are called the waters of deeper aquifers. Interstratal waters, being deeper and therefore cleaner, are most often used for water supply. They can be non-pressure and pressure.

Non-pressure waters are characterized by the presence of a free surface, established under the influence of gravity (for example, groundwater); pressure the same waters have an increased hydrostatic pressure and tend to increase their level in the workings, which is associated with the lack of a free exit of water in the conditions of the curvature of the aquifer and the presence of waterproof roofs and soles. Pressure also includes artesian waters.

§ 25. Groundwater

To characterize the groundwater of a given area, the level of groundwater is established, as well as the direction and speed of water movement in the rock.

When crossing the groundwater level by any working (pit, pit, borehole, etc.), water oozes from its walls, which over time fills part of the working. The level at which water began to ooze from the walls of the working is called emerging level. The level of water, established in the development, is called established level. In groundwater, these levels most often coincide. In the presence of pressure, which often happens in formation waters, the established level is higher than the appeared one.

Since the upper level of groundwater has great importance in road construction, then in boreholes and pits laid during road surveys, they usually measure the depth of these waters using a measuring tape, rail, etc.

The groundwater level is not constant. Depending on weather conditions (rainy weather, dry period of the year, etc.), the depth of groundwater rises or falls. Groundwater lying close to the day surface is especially susceptible to fluctuations.

Lines connecting the same levels of standing groundwater are called hydroisohypses. On special hydrogeological maps, hydroisohypses are drawn as horizontals on topographic maps, after 1, 2, 3 and 5 m, depending on the number of observations and the required accuracy.

Water in rocks is only in rare cases in a stagnant state. Most often, it moves due to different pressures at two points and moves from high level to low.

Groundwater movement can also be driven by the slope of the Impermeable Seam. Moving groundwater is called ground stream, and stagnant water is called ground lake.

In many cases, it becomes necessary to determine the direction and speed of the ground flow in order to intercept it with a deep ditch and divert water away from the structure. For this, the following methods are used; a ) coloring substances; b) determining the direction by three points; c) hydroisogypsum.

Method of coloring substances. In the area under study, five pits or wells are laid (Fig. 19). In the middle of them, a coloring substance that dissolves in water is introduced in the amount of 2–20 g for every 10 m of the distance between the wells. In the remaining wells, they carefully monitor the appearance of color. The well, in which colored water appears first, lies closest to the direction of groundwater movement.

Since the coloring matter appears in the observables! wells are very weakened, which makes it impossible to accurately determine the time of its appearance, then often instead of it, a concentrated solution of sodium chloride or other salt is injected into the central well. The appearance of this salt in other wells is established by reaction with silver nitrate, as a result of which a white flaky precipitate of silver chloride is formed.

Having data on the distance between the well in which colored water appeared, as well as on the time I of the passage of water along this path, the speed of the ground flow is determined:

The ground flow speed usually ranges from 3-12 m per day.

— Determination of flow direction by three points. In places where it is necessary to determine the direction of movement of groundwater, three wells or wells are selected, located in the form of a triangle. For each of the wells, groundwater levels are determined. To do this, leveling first determines the marks of the earth's surface at the well or well, then accurately measures the depth of groundwater and sets the water level marks in the wells by calculation.

The desired direction of the ground flow is set graphically (see Fig. 19). By connecting points A, B and C with solid lines, they divide side AB, where there is the greatest difference in levels, by the difference in marks, i.e. by five equal parts. Assuming a uniform drop in level from well A to well B (interpolation), they find point D, the level of which corresponds to the water level in well B. A straight line perpendicular to the line connecting points D and B will be the desired flow direction, as the shortest, and is called the line of hydroisohypses.

§ 26. Pressure waters and springs

Groundwater located in aquifers of various rocks lying between water-resistant layers (mainly in bedrock) is called pressure, or artesian, waters. The most typical is the occurrence of these waters in synclinal folds (Fig. 20). ‘From fig. 20 it can be seen that the water in aquifer 1 is not blocked by waterproof rock, and its level is free (ground water), while water in layers 2 and 3 is under pressure (pressure) due to the presence of waterproof rocks in the level of these layers and high position of the power area (P). Line a1-b1 shows the level to which water will rise from aquifers 2 and 3 when opened by boreholes. This level is called piezo-metric. If a well is laid at point A to aquifers 2 and 3, then the water will rise through the pipe and will spurt out like a fountain. Such wells are called artesian. There are also fissure pressure waters confined to fissured rocks of any origin.

Artesian waters are of great importance in the water supply of cities and towns. Due to pollution, groundwater lying close to the day surface cannot always be used for drinking. Artesian waters are usually benign, and their pressure allows you to get good drinking water without the use of water-lifting means.

In the USSR, pressure waters are found in the Moscow coal basin, in the Leningrad region, in the Ukraine and in many other places where they are widely used to supply cities with water.

Natural outlets of groundwater to the day surface are called sources (keys, springs). There are two main types of sources: descending and ascending.

Downstream springs are confined to the intersection of the aquifer with earth's surface, which usually happens on the slopes of erosional river valleys, in ravines and gullies (see Fig. 18). This type of spring is characterized by the absence of pressure.

Rice. 20. Artesian water and ascending springs:

A - artesian well with flowing water; B - an ordinary well. П - area of ​​nutrition, в - water-permeable e and « - water-impermeable layers; ab - groundwater level; o»b1 - piezometric level of pressure water

Ascending springs are confined to the exit to the surface of interstratal or fissure waters, which are under significant pressure. The water from these springs rises from the bottom up and exits in the form of a jet, often breaking through sediments (see Fig. 20). Both downstream and upstream sources are widely used for water supply.

The amount of water flowing to the well (well) per unit of time is called the debit of the source. The flow rate is calculated in liters per second or in cubic meters per day.

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Ground and interstratal non-pressure water

ground water in the narrow sense of this definition, free gravitational waters of an aquifer lying on the first water-resistant layer are called.

Depending on the nature of the occurrence of rocks, there are ground stream and ground pool(Rice.

3). In nature, various combinations of these types of occurrence are observed.

Rice. 3. Scheme of occurrence of groundwater:

a - ground flow, b - ground pool.

Waters lying in a permeable rock mass enclosed between two impervious layers are called interstratal waters. The upper waterproof layer in this case is called waterproof roof , and the bottom waterproof bed .

artesian waters

Groundwater usually has a free level surface. Interstratal waters also have a free surface, if they are free-flowing or if the aquifer is incompletely saturated with water.

Accumulations of groundwater are noted both in loose clastic rocks and in fractured massive igneous or highly metamorphosed sedimentary rocks. In the first case, the waters are of the type formation water. They are usually evenly distributed throughout the reservoir and their movement is carried out through small pores and voids between the grains that make up the rock. In the second case, the waters are called fissure-vein. Their distribution and movement is confined to cracks and large voids. It is not always possible to clearly distinguish between formation waters and fractured waters, therefore, they distinguish between fractured formation water.

The area of ​​distribution of groundwater, with rare exceptions, coincides with area of ​​their food, i.e., with an area within which atmospheric precipitation waters penetrate the soil and soil and can replenish groundwater supplies. The area of ​​distribution of interstratal waters does not coincide with the area of ​​their supply. The main feeding areas of these waters are confined to the places where the water-bearing rock comes out to the earth's surface. Additional nutrition of interlayer waters is obtained due to the seepage of waters from higher aquifers through relative aquicludes.

Groundwater is formed:

- on interfluve massifs,

- in alluvial deposits of river valleys,

— in foothill alluvial cones;

- in areas of glacial deposits,

- in intermountain depressions and basins,

- in places of accumulation of sand and pebble deposits of mountain rivers,

- in the areas of distribution of karst.

In vivo groundwater table is usually not a horizontal surface, but a wavy one and very often repeats the ground relief in a smoothed form. This is due to various reasons: the heterogeneity of rocks in terms of permeability both in the aeration zone and in the saturation zone, different seepage rates and different conditions for groundwater supply and their release to the surface at the intersections of the aquifer with river valleys , ravines, etc. To the place where groundwater comes out to the surface, their level decreases. Such a decrease in the level is also observed in interstratal non-pressure waters.

Depth groundwater can be different: from tens of meters to 1-2 m. In the latter case, they usually merge with soil water in the spring and form, as mentioned above, soil-groundwater. A variation of the latter is bog groundwater, the mirror of which is located within the peat deposit.

Free-flow interstratal water(Fig. 4) are usually confined to aquifers of considerable thickness cut through by a hydrographic network. These waters are usually shallow. River valleys sometimes cut through several layers of interstratal waters. In this case, in places of drainage at different levels of the slope of the valley (basin), waters come to the surface and are stable sources of food for surface watercourses and reservoirs.

Rice. Fig. 4. Scheme of groundwater occurrence: 1 – perched water; 2 - interstratal

non-pressure water; 3 - groundwater; 4 - interlayer pressure

water; 5 - surface reservoir.

Pressure water (Fig. 4)

Pressure water (artesian groundwater) — water that saturates the permeable layer enclosed between impervious rocks and has hydrostatic head.

Pressure waters are usually confined to the geological structures of sedimentary rocks with a corresponding overlay of permeable and water-resistant layers or to a complex system of tectonic cracks and faults.

A geological structure (depression, trough, syncline, monocline, etc.) containing one or more aquifers and providing pressure in them is called artesian basin.

In the artesian basin, they usually distinguish :

- food area

- area for the time,

— in some cases the area of ​​​​drainage (unloading) of pressure water.

The areas occupied by artesian basins fluctuate over a very wide range.

When opening the roof of a confined aquifer by a borehole, water under hydrostatic pressure rises above the roof of the aquifer and sometimes reaches the surface of the earth or even gushing (Fig. 5).

In the confined aquifer, thus, they distinguish geometric level, coinciding with the lower surface of the waterproof roof of the aquifer, and hydrostatic, or piezometric level, coinciding with the level of water rise in wells. The pressure at each point of the aquifer is measured by the height to which the water in the well rises above the lower surface of the waterproof roof when the aquifer is opened. As the formation sinks, the pressure usually increases.

Rice. 5. Scheme of the structure of the artesian basin.

1 - waterproof rocks; 2 - pressure aquifer; 3,4 - wells; 5 - flow direction; Sun — piezometric level, BNC - the bottom surface of a water-resistant roof, H1, H2: - pressure height.

Heated in the bowels of the earth, and most often coming out to the surface under pressure.

The most common hot springs are geysers, which periodically act as fountains. Fountains of hot water sometimes reach a height of tens of meters. There are many geysers and other geothermal sources in Kamchatka, the Kuril Islands, on the island of Iceland and in other volcanic regions (Fig. 47).

In Russia

In Russia, the first geothermal station was built in 1966 on the Kamchatka Peninsula, where there is an abundance of underground hot springs. One of the largest "hot" seas in Russia was found under the West Siberian Lowland. This sea extends from the hot steppes of Kazakhstan to the coast of the Arctic Ocean. The water of this underground sea is used for agricultural and other needs: it heats greenhouses, it goes to swimming pools.

Hot underground water is also used for the needs of the economy in the Caucasus, on the Kuril Islands and in a number of other places. Perhaps in the future hundreds of cities and towns will be heated by the warmth of the bowels of the earth. settlements. This will save millions of tons of fuel.

Word " balneology"means" the science of bathing.
Currently under balneology refers to that part of the science of resorts that studies the origin of mineral springs, their physical and Chemical properties, technical devices for their therapeutic use, the physiological basis of the influence of mineral waters on the body, the clinical course of diseases after the internal and external use of mineral waters.

Balneology is divided into: 1) balneography, which describes and characterizes resorts and medical areas; 2) balneotherapy - the science of the internal and external use of medicinal waters; 3) balneotechnics, in which technical measures are developed for the arrangement and equipment of springs, bathroom buildings, pools, water heating, etc.

Mineral water differs from the ordinary one in special physical and chemical properties, temperature, smell, color, taste and specific physiological effect on the body; the water of mineral springs is usually called curative.

Origin of mineral springs and their properties

There was and exists a number of theories about the origin of medicinal waters. The most ancient theory explained the origin of underground, including mineral, waters by the penetration of atmospheric precipitation into the soil to a great depth, their accumulation on water-resistant layers and subsequent emergence to the surface of the earth.

Now established that: 1) the waters of mineral springs are obtained from atmospheric precipitation or come out of the unexplored bowels of the earth; 2) they either acquire their mineralization as a result of the dissolution and decomposition of the rocks under which they pass, or they bring it from the bowels of the earth; 3) mineral water gases are formed during chemical processes in the soil, and also appear as a result of underground volcanic activity; some of them are released from the atmosphere during the formation of precipitation. The waters formed in the bowels of the earth and first appearing on its surface are called "juvenile", in contrast to other mineral waters, called "water", that is, surface. Most of the deep waters, that is, those coming from the deep bowels of the earth, are of a mixed type and consist of juvenile and water water.

Quantity water in mineral springs depends on their origin: in some sources it is constant, in others it varies depending on the season, the amount of precipitation or volcanic activity in the bowels of the earth. The amount of water supplied by the source is calculated in liters per second or hectoliters per day. For example, the Batalinsky spring, near Pyatigorsk, gives 720 hectoliters per day. Narzan in Kislovodsk - 1980,000 years old

Temperature of mineral springs depends mainly on the thermal conditions that are observed in the earth's crust, and on the average annual temperature of the area. There are springs whose temperature is slightly above freezing (for example, Darasun in Transbaikalia), in some springs the temperature reaches the boiling point (Goryachevodsk). In most cases, the temperature of medicinal waters approaches the temperature of spring water. Those sources, the water temperature of which is above 37 °, are usually called terms, that is, warm. According to the international balneological classification, mineral water depending on the temperature, they are divided into the following groups: 1) cold (below 20 °); 2) moderate, or subthermal (from 20 to 36 °); 3) warm, or thermal (from 37 to 42 °); 4) hot, or hyperthermal (above 42°). Waters that have a high temperature with a low mineralization and a low content of gases are called acrotherms.

The content of the article

A SOURCE, natural outlet of groundwater to the earth's surface. Groundwater is located in the cavities, pores and cracks of rocks in the upper part earth's crust. The upper boundary of the water-saturated zone is called the mirror, or level, of groundwater. Where aquifers intersect with the earth's surface, springs arise. Because the depth of the water table varies with the season and the amount of rainfall, springs can suddenly disappear, seep, drip, or swell.

Sources on the slopes of the hills.

In dissected terrain, some of the water that seeps into the soil at the top of the hill may resurface downslope as a source above the watercourse (Figure 1). This happens if the groundwater table is above the level of the watercourse. Sources arise where water, when moving down, meets an impermeable horizon, and then comes to the surface at the place where permeable rocks are exposed. The discharge of water from springs on hillsides is usually small and variable.

Artesian springs.

Water entering porous permeable layers covered by impermeable rocks can gush under pressure in low-lying outlets, forming an artesian source. Sometimes artesian aquifers occupy a significant area, and then artesian sources have a high and fairly constant flow of water. Some of the well-known oases in North Africa are associated with such artesian springs. Where there are faults in the earth's crust, artesian waters rise from aquifers along fault lines. Between the rainy seasons, they often dry up.

Karst springs.

The largest springs in the world are often associated with the release of water from karst limestones. Containing carbon dioxide percolating waters can dissolve limestones, so karst caves and channels are common in many limestone areas. In such areas, underground rivers and very large karst springs are quite common, for example, Vaucluse in the south of France, considered one of the most powerful in the world, and Silver Springs in Florida, famous for its amazing purity of water.

Sources in porous lavas.

There are large springs in places where groundwater comes out of horizons composed of porous fissured lavas. For example, a group of such springs, confined to a lava plateau, feeds the Snake River below Shoshone Falls (Idaho).

The hot springs.

Most hot springs are confined to volcanic areas in which water is heated from rocks, the upper layers of the earth's crust, located near volcanoes, although some of the water may be of magmatic origin. In some hot springs (for example, Warm Springs in Virginia), the high water temperature is due to the rise of water from great depths (after all, the temperature of the rocks rises by about 1 ° C with an increase in depth of 30 m).

Mineral springs.

The water of mineral springs contains a significant amount of dissolved chemical substances. Warm and hot springs usually have higher salinity because chemical reactions proceed more rapidly at elevated temperatures.

Geysers are gushing hot springs in areas of volcanic activity.