Groundwater is water that is in a solid, liquid or vaporous state in the upper layers of the earth's crust, in the thickness of rocks. They relate to hydrosphere resources. In the areas where such waters are located, the temperature ranges from minus ninety-three to plus one thousand two hundred degrees, and the pressure in their thickness is from several units to three thousand MPa.
Underground water resources are subdivided according to their location into the following types:
- pore, located in pebbles, sandy and various clastic rocks ;
- fissured or vein flowing in sandstones and granites;
- karst, located in gypsum, dolomite, limestone and other soluble rocks.
Gravity or free water moves under the influence of gravity. In contrast, the associated water resources form strata or horizons in the rocks.
The very first layer from the earth's surface is a layer that exists without pressure. It is called the "groundwater horizon." Its depth is directly dependent on the geographical location of the area. The change in bedding parameters occurs from the poles to the equatorial zone.
In the European regions of Russia, the average depth of the horizon of the soil layer increases gradually from the northern to the southern regions. If in the tundra zone groundwater is located directly at the surface of the earth's crust, then in the southern regions - at a depth of several tens of meters. The maximum depth of these water resources ranges from ten to twelve kilometers.
Groundwater is a solution that contains over sixty chemicals, as well as various microorganisms. Basically, these water resources are saturated with gases. The waters located in the upper layers of the earth's crust are divided into types depending on the degree of saturation with minerals. Distinguish:
- fresh;
- brackish;
- salted;
- underground brines.
The origin of groundwater is reflected in their typical classification:
1. The infiltration layers are formed by seepage of river, rain or melt water from the earth's surface.
2. Condensation horizons are the result of condensation processes of water vapor in cracks or in the pores of rocks.
3. Sedimentation underground water resources are formed as a result of sedimentation of the geological type. They are usually buried waters of marine origin. This also includes ultra-fresh layers located in moraine deposits, as well as salt-water pools.
4. Groundwater, belonging to the magmatogenous type, originated from magma, which went through the crystallization process, as well as from rocks as a result of their metamorphism.
Most quantitative and qualitative indicators (pressure level, flow rate, gas and chemical composition, temperature, etc.) of the soil layers are subject to both short-term and long-term changes that determine their general mode. In this case, the greatest fluctuations in characteristics are manifested with a shallow occurrence of water reservoirs.
Hydro resources located in the upper layers of the earth's crust belong to the category of renewable minerals. In order to protect against depletion and pollution, to control the operation, and also to prevent negative consequences during water intake, groundwater is monitored. The organization, as well as the maintenance of these control measures, is the direct responsibility of those legal entities that have received a license for the extraction and use of natural hydro resources. During the production of monitoring, an inspection of the sanitary intake zone is also conducted. These works are designed to identify sources of likely groundwater pollution and recommend guilty business entities to eliminate violations.