Groundwater is those that are below the earth's surface. The groundwater they are a part of the total fresh water on the planet. They make up 21% of the total fresh water on Earth and also twenty times more of the water on the surface. If you want to know how groundwater is formed, then keep reading this article because in Ecologista Verde we discover the answer, as well as details such as its location and classification, its importance and also the reason why, in turn, they are part of a great environmental problem.
The water from the rain can go to different destinations. It can either flow through the surface forming rivers, streams or other forms of runoff, be absorbed by organisms or, water can seep into the ground and form groundwater.
What definition of groundwater we can say that these include all kinds of water found in the ground. In order for water to enter the soil, it must have a series of characteristics. There are permeable soils, which allow water to pass through, such as sands and stones, and impermeable soils such as volcanic and metamorphic rocks.
The water, once it reaches the subsoil, can accumulate in different ways and at different depths and even erode the rock creating an underground landscape. In addition, they have a great ecological and economic importance for human beings, and precisely because of this they are also suffering the negative consequences of human action. All of this is explained in more detail below.
One type of groundwater is gravitational water. Gravitational water is the water found in the pores of the earth. The sandy and stony soils contain more pores due to the large size of the grain they have and leave holes with air that, when it rains, fill with water by infiltration into the ground and remain stored.
If more water accumulates we can differentiate 3 types of water reservoirs: aquícludos, aquitardos and aquifers. Acuícludos are deposits of silt and clay that contain water, but due to its low permeability it cannot be moved or extracted. Aquitards are geological formations, generally of clayey sands, sandstones or slightly fractured and compressed rocks that contain a lot of water, which can circulate, but slowly. And finally, aquifers are geological formations of sand, gravel or other fragmented or fissured rocks that contain a large amount of water that can move freely.
Generally, they are distinguished 3 types of aquifers:
Groundwater is brought to the surface by springs or lakes due to infiltration on the ground surface. In these cases the groundwater flows to the lakes by springs below the lake surface. It may be that the lakes originate from their bottom when the groundwater emerges, or that the aquifer is recharged by the movement of rain and meltwater, accumulated in the lakes, towards the interior of the earth, and also maintains the lake because the water table of the aquifer is above the ground surface. Fossil water is that found in aquifers that have not been recharged for a long time.
Groundwater has different characteristics from rivers, lakes and ponds, wetlands, estuaries, and other types of surface water. They do not usually contain dissolved gases, are under pressure and normally move slowly between rocks, although the fractures between them often provide channels through which water flows at high speed.
When groundwater runs through soils formed by limestone rock, they dissolve the material and form the karst landscape. Some typical formations are caves, stalactites, stalagmites, chasms and galleries among others. They provide shelter for animals, such as bats or many invertebrates, which in turn are food for other animals. These spaces are also used by man to practice sports such as caving or adventure tourism.
In addition, groundwater when it circulates in caves or through sands and gravels can carry living material such as bacteria, and animals such as small crustaceans and insects that feed on the bacteria.
Groundwater represents one of the most important water supplies for the population. Groundwater is a source of drinking water. It is often obtained from springs and wells, natural or man-made. About 50% of the human population is supplied by groundwater and is used both for human consumption and for livestock and agriculture. It is so important that, for example, in the United States, 95% of the rural population depends on them.
Groundwater can be easily polluted due to their slow movement and being out of sight.
Also, water tends not to mix, so feathers from salty or polluted water can move long distances. The volatile pollutants contained in them cannot evaporate.
Water pollution can occur naturally, since the water moving over the rocks can carry the toxic substances they contain, such as some metals. But the most common form of contamination is anthropic, that is, by humans. It can be due to the use of pesticides and fertilizers in agricultural areas, wastewater and raw water in urban and industrial areas, and increased nitrate levels. The latter is one of the most worrying because once it reaches the subsoil it is transformed into other compounds that can cause health problems and diseases, such as cancer when this water is ingested.
One of the big problems is overexploitation of groundwater. It occurs when water is withdrawn at a faster rate than it is replenished. Overexploitation of an aquifer can mean:
Now that you know well what groundwater is, how it is formed and its importance, as well as the environmental problems that are related to it, you may also be interested in knowing the information in this other article by Green Ecologist on Why water is a renewable but limited resource.
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