Water is the most common substance on our planet, thanks to which life is maintained on it. It is located in the lithosphere and in the hydrosphere. Earth's biosphere consists of ¾ of water. An important role in the circuit of a given substance is played by its underground species. Here it can be formed from mantle gases, in the process of atmospheric precipitation runoff, etc. In this article we will consider the types of groundwater.
The concept
Underground waters mean the latter, located in the earth's crust, located in rocks located below the surface of the Earth in various states of aggregation. They form part of the hydrosphere. According to V.I. Vernadsky, these waters can be located at a depth of up to 60 km. The estimated volume of groundwater located at a depth of 16 km is 400 million cubic km, that is, a third of the waters of the oceans. They are located on two floors. In the lower of them are metamorphic and igneous rocks, so there is a limited amount of water. The bulk of the water is located on the upper floor, in which sedimentary rocks are located.
Classification by nature of exchange with surface waters
It distinguishes 3 zones: the upper - free; middle and lower - slow water metabolism. Types of groundwater in composition in different zones are different. So, in the upper of them are fresh water used for technical, drinking and household purposes. In the middle zone are ancient waters of various mineral composition. In the lower part are highly saline brines, from which various elements are mined.
Mineral Classification
The following types of groundwater are distinguished by mineralization: ultra-, fresh, with relatively high salinity — only the last group can reach a salinity of 1.0 g / cu. dm; brackish, salty, high salinity, brines. In the latter, mineralization exceeds 35 mg / cu. dm.
Classification by occurrence
The following types of groundwater are distinguished according to the occurrence conditions: vodovodka, groundwater, artesian and soil waters.
Vovodovka is mainly formed on lenses and wedged out layers of poorly permeable or water-resistant rocks in the aeration zone during infiltration of surface and atmospheric waters. Sometimes it is formed due to the illuvial horizon under the soil layer. The formation of these waters is associated with the processes of condensation of water vapor in addition to those listed above. In some climatic zones, they form quite large reserves of high-quality water, but mostly thin aquifers are formed, which disappear during drought and form during periods of intense moisture. Basically, this type of groundwater is characteristic of loam. Its thickness reaches 0.4-5 m. The relief has a significant effect on the formation of the upper water. On steep slopes, it exists for a short time or is absent altogether. On flat steppes with depressions in the form of saucers and flat watersheds, on the surface of river routes, a more stable overhead water forms. It has no hydraulic connection with river waters, and is easily contaminated with other waters. At the same time, it can feed groundwater, and can be spent on evaporation. The high water can be fresh or slightly mineralized.
Groundwater is part of the groundwater. They are located on the first aquifer from the surface, lie on the first aquifer, sustained by area. Basically, they are free-flowing waters; they can have a small pressure in areas with local watertight overlap. Depth, their chemical and physical properties are subject to periodic fluctuations. Distributed everywhere. They feed by means of sediment infiltration from the atmosphere, filtration from surface sources, condensation of water vapor and intra-ground evaporation, additional nutrition coming from lower aquifers.
Artesian waters are part of the groundwater that has a head that lies in aquifers between relatively water-resistant and water-resistant strata. They lie deeper than dirt. In most cases, their nutrition and pressure areas do not coincide. Water appears in the well below a steady level. The properties of these waters are less susceptible to fluctuations and pollution compared to groundwater.
Soil waters are those that are confined to the soil water layer, take part in the supply of plants with this substance, and are associated with the atmosphere, high water and groundwater. They have a significant effect on the chemical composition of groundwater during their deep occurrence. If the latter are shallow, then the soil is waterlogged and waterlogging begins. Gravity water does not form a separate horizon, the movement is carried out from top to bottom under the action of capillary forces or gravity in various directions.
Formation classification
The main types of groundwater are infiltration, which are formed due to seepage of precipitation. In addition, they can be formed as a result of condensation of water vapor, which enters the fractured and porous rocks together with air. In addition, relict (buried) waters are distinguished, which were in ancient basins, but were buried by thick layers of sedimentary rocks. Thermal waters, which were formed at the last stages of magmatic processes, also go as a separate species. These waters form magmatogenic or juvenile species.
Classification of the movement of the considered objects
The following types of groundwater movement are distinguished (see. Figure).
Seepage of surface water and precipitation from the atmosphere occurs in the aeration zone. Moreover, this process is divided into freely carried out and normal infiltration. The first involves the movement from top to bottom under the influence of gravity and capillary forces along certain tubules and capillary pores, while the porous space is not saturated with water, which helps to maintain air movement. During normal infiltration, hydrostatic pressure gradients join the forces listed above, which leads to the fact that the pores are completely filled with water.
In the saturation zone, hydrostatic pressure and gravity act, which contributes to the movement of free water along cracks and pores to the sides, a decrease in pressure or slope of the surface of the horizon carrying water. This movement is called filtering. The highest water velocity is observed in underground karst caves and canals. In second place are pebbles. A much slower movement is observed in the sands - the speed is 0.5-5 m / day.
Types of groundwater in the permafrost zone
These underground waters are classified as permafrost, intermafrost and permafrost. The former are located in the thickness of permafrost on the aquifer, mainly at the foot of slopes or at the bottom of river valleys. They, in turn, are divided into seasonally freezing, high water located in the active layer; on seasonally partially freezing, with the upper part in the active layer; on seasonally non-freezing, the occurrence of which is noted below the seasonally freezing layer. In some cases, the active layer of various soils may rupture, which leads to the release of some of the permafrost waters to the surface, where it takes the form of ice.
Inter-permafrost waters may be present in the liquid phase, but are most prevalent in the solid phase; usually not susceptible to seasonal thawing / freezing. These water in the liquid phase provide water exchange with supra-permafrost waters. They can come to the surface like springs. Frozen waters are artesian. They can be from fresh to pickles.
The types of groundwater in Russia are the same as those discussed above.
Contamination of the objects in question
The following types of groundwater pollution are distinguished: chemical, which, in turn, is divided into organic and inorganic, thermal, radioactive and biological.
Chemical pollutants are mainly liquid and solid wastes from industrial enterprises, as well as pesticides and fertilizers from agricultural producers. Heavy metals and other toxic elements most affect groundwater. Over aquifers, they spread over considerable distances. Radionuclide pollution behaves in a similar manner.
Biological pollution causes pathogenic microflora. Sources of pollution are usually cattle yards, filtration fields, faulty sewers, cesspools, etc. The spread of microflora is determined by the filtration rate and the survival of these organisms.
Thermal pollution is an increase in groundwater temperature that occurs during the operation of a water intake. It can occur in waste water discharge areas or when the intake is located near a reservoir with warmer surface waters.
Subsoil use
Groundwater production as a type of subsoil use is regulated by the Federal Law "On Subsoil". The extraction of these objects requires a license. It is issued in relation to groundwater for up to 25 years. The term of use starts from the moment of state registration of the license.
Mining operations must be registered with the Federal Registration Service. Next, they draw up a project for exploration and transmit it to the state examination. Then they prepare a project for the organization of the sanitary sanitation zone of the underground water intake, estimate the reserves of these waters and transfer the calculations to the state expert examination, the geoinformation fund and the Rosgeolfond. Next, certificates of ownership of land are attached to the received documents, after which an application for a license is submitted.
Finally
What types of groundwater are there in Russia? The same as in the world. The area of our country is quite large, so it has permafrost, and artesian, and ground, and soil waters. The classification of the objects under consideration is quite complicated, and in this article it is incomplete, its most basic points are shown here.