An aquifer or horizon is several layers of rocks with high permeability. Their pores, cracks or other voids are filled with groundwater.
General concepts
Several aquifers can form an aquifer complex if they are hydraulically connected. Water is used for water supply in forestry, for irrigation of forest nurseries, in human economic activity. Upon reaching the surface, they can become a source of swamping of the territory. This may contribute to the formation of lowland and transitional bogs.
Water permeability
The aquifer is characterized by water permeability of rocks. Water permeability depends on the size and number of interconnected cracks, pores, as well as on the sorting of the granules of rocks. The depth of the aquifer can be different: from 2-4 m (“top”) and up to 30-50 m (artesian water).
Well-permeable rocks include:
- gravel;
- pebbles;
- coarse sand ;
- fractured and intensely karst rocks.
Water movement
There can be several reasons for the movement of water in the pores:
- the force of gravity;
- hydraulic head;
- capillary forces;
- capillary osmotic forces;
- adsorption forces;
- temperature gradient.
Depending on the geological structure, the rocks of the aquifer can be isotropic in terms of filtration, i.e., water permeability in any direction is the same. The rocks can also be anisotropic, in which case they are characterized by a uniform change in water permeability in all directions.
The depth of aquifers in the Moscow region
Throughout the territory of the Moscow Region, the depth of groundwater is not the same, therefore, for the convenience of study, it was divided into hydrological regions.
There are several aquifers:
- South area. The water level can be between 10-70 m. The depth of the wells in this area varies from 40 m to 120 m.
- Southwest area . The water horizon is not abundant. The average depth of the wells is 50 m.
- Central District. This is the largest area. He, in turn, is divided into Big and Small. The average thickness of the horizons is 30 m. The waters here are carbonate, carbonate-sulfate.
- East area. The depth of the aquifer in this area is 20-50 meters. The waters are mainly highly mineralized, therefore unsuitable for water supply.
- Klinsko-Dmitrovsky district. It consists of two horizons of the upper carbonate: Gzhel and Kasimovsky.
- Volga region. The average depth of the aquifer is 25 meters.
This is a general description of the areas. In a detailed study of aquifers, consider the composition of the water layer, its thickness, specific rate, sediment density, etc.
It is worth noting that the hydrogeology of the Moscow region distinguishes one aquifer complex, which is divided into several horizons of the Paleozoic coal deposits:
- Podolsk-Shcholkovsky layer of middle carbon;
- the Serpukhov aquifer and the Oka Formation of the Lower Carboniferous;
- Kashira aquifer middle Carboniferous;
- Kasimov layer of the upper carbon;
- Gzhel aquifer of the Upper Carboniferous.
Some aquifers have little water saturation and high salinity, therefore, they are unsuitable for human economic activity.
The aquifer of the Serpukhov and Oka Formations of the Lower Carboniferous has a maximum thickness relative to other aquifers - 60-70 meters.
The Moscow-Podilsky aquifer can reach a maximum of 45 meters in depth, its average thickness is 25 meters.
How to determine the depth of the aquifer
Sandy aquifer - a conditional name, because this horizon may consist of pebble, a mixture of sand and pebble. Sandy aquifers have different thicknesses; their depths also vary.
If we consider the hydrogeology of the Moscow region and the adjacent areas, we can say with confidence that groundwater can be found already at a depth of 3-5 meters, depending on the relative height of the studied area. The depth of the aquifer also depends on nearby hydrological objects: river, lake, swamp.
The layer closest to the surface is called the “lead”. It is not recommended to use its water for food, because the nutrition of this layer is due to precipitation, melting snow, etc., therefore, harmful impurities can easily get here. However, often the waters of the “Verkhovodka” are used on the farm, and they also call it “process water”.
Good filtered water is at a depth of 8-10 meters. At a depth of 30 meters are the so-called "mineral waters", for the production of which artesian wells are being built.
It is relatively easy to determine the presence and depth of the upper aquifer. There are many folk ways: using a vine or a metal frame, using a clay pot, by observing plants growing on the territory.