Groundwater is the water beneath the Earth's surface in the pore spaces of the soil and in the fracture of rock formations. An unconsessed rock or sedimentary unit is called an aquifer when it can produce a usable amount of water. The depth at which the pore space of the soil or fracture and the void in the rock becomes completely saturated with water is called the water table. Groundwater is recharged and eventually flows to the surface naturally; natural discharges often occur in springs and seeps, and may form oases or wetlands. Groundwater is also often drawn for agricultural, municipal, and industrial uses by constructing and operating extraction wells. The study of groundwater distribution and movement is hydrogeology, also called groundwater hydrology.
Typically, groundwater is regarded as water flowing through a shallow aquifer, but, in technical terms, this water can also contain soil moisture, permafrost (frozen ground), immobile water in very low permeability rocks, and water geothermal or deep oil. Ground water is hypothesized to provide lubrication that may affect cesarean delivery. It is likely that most of the subsurface of the earth contains water, which can be mixed with other liquids in some instances. Groundwater may not be limited to Earth. The formation of some of the landscapes observed on Mars may have been influenced by ground water. There is also evidence that liquid water may also exist beneath the surface of Europa Moon Jupiter.
Groundwater is often cheaper, more comfortable and less susceptible to pollution than surface water. Therefore, it is commonly used for public water supplies. For example, ground water provides the largest usable water storage resource in the United States, and California annually attracts the largest groundwater of all states. The underground reservoir contains far more water than the capacity of all US surface and lake reservoirs, including the Great Lakes. Much of the city's water supply comes only from ground water.
The contaminated soil water is less visible, but more difficult to clean, than pollution in rivers and lakes. Groundwater pollution is most commonly caused by improper waste disposal on land. Major sources include industrial and household chemicals and waste disposal premises, excessive fertilizers and pesticides used in agriculture, industrial waste lagoons, tailings and process wastewater from mines, industrial fracking, oil pits, underground storage tanks leaking and pipelines, sewage sludge and septic systems.
Video Groundwater
Aquifer
A aquifer is a porous substrate layer that contains and transmits ground water. When water can flow directly between the surface and the saturated zone of an aquifer, the aquifer is unfettered. The deeper part of the free aquifer is usually more saturated because gravity causes water to flow down.
The upper level of the saturated layer of this free aquifer is called water surface or phreatic surface . Below the surface of the water, where in general all the pore spaces are saturated with water, is a phreatic zone.
Substrates with low porosity that allow limited groundwater transmission are known as orangitard . An aquiclude is a substrate with a very low porosity that is almost impermeable to groundwater.
A limited aquifer is an aquifer overlaid by a relatively impermeable layer of rock or substrate such as aquiclude or aquitard. If the aquifer is confined to the descending grade of the affix zone, groundwater may become pressurized as it flows. This can create artesian wells that flow freely without the need for pumps and rise to higher altitudes than static water tables in the aquifer above, without bonds.
The characteristics of the aquifer vary with the geology and structure of the substrate and topography in which they occur. In general, more productive aquifers occur in sedimentary geological formations. By comparison, rotted and cracked crystal rocks produce less ground water in many environments. Unconsolidated for poorly cemented alluvial materials that have accumulated as valley filling sediments in major river basins and geologically overhauling structural basins are among the most productive groundwater sources.
The high specific heat capacity of water and the effects of soil and rock insulation can reduce climate effects and keep ground water at a relatively stable temperature. In some places where groundwater temperatures are maintained by this effect at about 10 Ã, Â ° C (50Ã, Â ° F), groundwater can be used to control the temperature inside the structure on the surface. For example, during hot weather the relatively cool groundwater can be pumped through the radiator at home and then back to the ground at other wells. During the winter, as it is relatively warm, water can be used in the same way as a heat source for heat pumps which is much more efficient than using air.
The groundwater volume in the aquifer can be estimated by measuring the water level at the local well and by checking the geological records of the well drilling to determine the extent, depth and thickness of the sediments and rocks that retain water. Before investments are made in production wells, test wells can be drilled to measure the depth at which water is encountered and collect soil, rock and water samples for laboratory analysis. The pumping test can be performed at the test well to determine the flow characteristics of the aquifer.
Maps Groundwater
Water cycle
Groundwater makes up about twenty percent of the world's freshwater supply, which is about 0.61% of all the world's water, including oceans and eternal ice. Global groundwater storage is approximately equal to the total amount of fresh water stored in snow and ice packs, including the north and south poles. This makes it an important resource that can act as a natural storage that can support the lack of surface water, such as in times of drought.
Groundwater is naturally recharged by surface water from deposition, streams, and rivers as this infiltration reaches the water surface.
Groundwater can be a long-term 'reservoir' of natural water cycles (with residence time from day to millennium), compared to short-term water reservoirs such as atmospheric and fresh surface water (which has a residence time from year to year). The picture shows how deep groundwater (which is far enough from surface filling) can take a very long time to complete its natural cycle.
The Great Artesian Basin in central and eastern Australia is one of the largest closed aquifer systems in the world, stretching nearly 2 million km 2 . By analyzing trace elements in underground water, hydrogeologists have been able to determine that the water extracted from this aquifer can be more than 1 million years old.
By comparing the age of groundwater obtained from different parts of the Great Artesia Basin, hydrogeologists have found an increase in age in the basin. Where water replenishes the aquifers along the Eastern Divide, a young age. As groundwater flows west across the continent, it increases in age, with the oldest groundwater occurring in the west. This means that in order to travel nearly 1000 km from a source of absorption in 1 million years, ground water flowing through the Great Artesian Basin runs at an average rate of about 1 meter per year.
Recent research has shown that ground water evaporation can play an important role in the local water cycle, especially in dry areas. Scientists in Saudi Arabia have proposed a plan to reclaim and recycle this evaporated moisture for crop irrigation. In opposite photos, a 50-centimeter reflective carpet, made of a small adjacent plastic cone, is placed in a plant-free desert area for five months, without rain or irrigation. He succeeds in capturing and condensing enough soil to revive the naturally buried seed underneath, with a green area of ​​about 10% of the carpet area. It is expected that, if the seeds are placed before placing this carpet, a much larger area will be green.
Problem
Overview
Certain problems affect the use of groundwater around the world. Just as river water has been overused and polluted in many parts of the world, so is the aquifer. The big difference is the invisible aquifer. Another major problem is the water management agency, when calculating the "sustainable results" of aquifers and river water, often counting the same water twice, once in aquifers, and once in a connected river. This problem, though understood for centuries, has persisted, partly through inertia within government institutions. In Australia, for example, prior to the law reform initiated by the Australian Government Board's water reform framework in the 1990s, many of Australia's states manage groundwater and surface water through separate government agencies, an approach that is competition and poor communication.
In general, the time lags inherent in the dynamic response of groundwater to development have been ignored by the water management agency, decades after the scientific understanding of the issue was consolidated. In short, the effect of a groundwater dorm (though it can not be denied) may take several decades or centuries to manifest itself. In a classical study in 1982, Bredehoeft and his colleagues modeled a situation in which groundwater extraction in an intermontane basin attracted an entire annual replenishment, leaving 'nothing' for the natural vegetation community dependent on groundwater. Even when borefield is located close to the vegetation, 30% of the original vegetation demand can still be met by the lag attached to the system after 100 years. In the year 500, this has been reduced to 0%, signifying the complete death of vegetation dependent on groundwater. Science has been available to make this calculation for decades; however, in general the water management agency has ignored the effects that will emerge beyond the grace period of political elections (3 to 5 years). Marios Sophocleous strongly argues that the management agency should determine and use the appropriate time frame in groundwater planning. This means calculating groundwater drawing permits based on estimates of the effects of the decade, sometimes centuries in the future.
As water moves through the landscape, it collects a soluble salt, especially sodium chloride. When such water enters the atmosphere through evapotranspiration, these salts are left behind. In irrigated areas, poor soil drainage and surface aquifers can cause surface water to surface in lowland areas. Major soil degradation problems from soil salinity and waterlogging results, combined with increased levels of salt on the water surface. As a result, massive damage occurs to the local economy and environment.
Four important effects deserve to be mentioned briefly. First, the flood mitigation scheme, intended to protect infrastructure built on floodplains, has unintended consequences for reducing aquifer recharges associated with natural flooding. Second, a prolonged depletion of ground water in a wide aquifer can lead to soil degradation, with associated infrastructure damage - and, third, salin intrusion. Fourth, drying of sulfuric acid soils, often found in lowland coastal plains, can lead to acidification and contamination from fresh water flow and estuary beforehand.
Another worrying cause is that too much groundwater removal from aquifers has the potential to cause severe damage to terrestrial and aquatic ecosystems - in some cases very striking but in others quite unnoticeable due to the long period where the damage occurred.
Overdraft
Groundwater is a very useful and often abundant resource. However, over-use, over-abstraction or overdraft , can cause major problems for human users and the environment. The most obvious problem (as far as the use of human groundwater is concerned) is the decrease of the water level beyond the reach of existing wells. As a result, wells must be drilled deeper to reach groundwater; in some places (eg, California, Texas, and India) water tables have dropped hundreds of feet due to the pumping of large wells. In the Punjab region of India, for example, groundwater levels have fallen by 10 meters since 1979, and their depletion rates are accelerating. A water-derived table may, in turn, lead to other problems such as subsidies related to ground water and saltwater intrusion.
Groundwater is also ecologically important. The importance of ground water for ecosystems is often overlooked, even by freshwater biologists and ecologists. Groundwaters support rivers, wetlands, and lakes, as well as underground ecosystems in karst or alluvial aquifers.
Not all ecosystems require groundwater, of course. Some terrestrial ecosystems - for example, open deserts and similar dry environments - exist in irregular rainfall and moisture given to the ground, coupled with moisture in the air. While there are other terrestrial ecosystems in a more hospitable environment where ground water does not play a central role, groundwater is in fact very important for many of the world's major ecosystems. Water flows between groundwater and surface water. Most rivers, lakes, and wetlands are fed by, and (at other times or places) feeding groundwater, to varying degrees. Groundwater feeds ground water through percolation, and many terrestrial vegetation communities depend directly on groundwater or groundwater that peels over the aquifer for at least part of each year. The hyporphic zone (river and ground water mixing zone) and riparian zones are examples of ecotone that are largely or completely dependent on groundwater.
Subsidence
Subsidence occurs when too much water is pumped out from under the ground, deflating the space below the surface above, and thus causing the ground to collapse. The result can look like a crater in a plot of land. This is because, in their natural equilibrium state, the hydraulic pressure of ground water in the pore chamber of the aquifer and the aquitar supports some of the weight of the above sediments. When groundwater is removed from the aquifer by excessive pumping, pore-water pressures in aquifer reduction and aquifer compression may occur. This compression can be partially recovered if the pressure rebounds, but most do not. When the aquifer is compressed, it can cause a decrease in soil, a decrease in ground level. The city of New Orleans, Louisiana is actually below sea level today, and its decline is partly due to the loss of ground water from various aquifer/aquifer systems underneath. In the first half of the 20th century, the San Joaquin Valley experienced a significant decrease, in some places up to 8.5 meters (28 feet) due to groundwater displacement. Cities in the river delta, including Venice in Italy, and Bangkok in Thailand, have experienced a decrease in the surface; Mexico City, built on a former lake bed, has experienced a decline rate of up to 40 cm (1'3 ") per year.
sea water intrusion
In general, in very humid or underdeveloped areas, surface water forms mimic the surface tilt. The affixed zone of aquifers near the coast tends to land, often at considerable distances. In this coastal area, the descending water table can cause sea water to reverse the flow to the land. The sea water moving inland is called salt water intrusion. In alternative modes, the salt from the mineral layer can seep into the groundwater by itself.
Pollution
The contaminated soil water is less visible, but more difficult to clean, than pollution in rivers and lakes. Groundwater pollution is most commonly caused by improper waste disposal on land. Major sources include industrial and household chemicals and final waste dumps, industrial waste lagoons, tailings and process wastes from mines, oil pits, leaking underground oil storage tanks and pipelines, mud waste and septic systems. Contaminated soil water is mapped by soil and groundwater sampling near suspected or known pollution sources, to determine pollution levels, and to assist in the design of groundwater remediation systems. Preventing groundwater contamination near potential sources such as landfill requires the bottom layer of the disposal site with waterproof material, collecting leachate with aqueducts, and preserving rainwater from potential contaminants, along with regular monitoring of nearby groundwater to verify that contaminants not leaking into groundwater.
Groundwater pollution, from pollutants released to soil that can work downwards into ground water, can create contaminant clumps in the aquifer. Pollution can occur from landfills, natural arsenic, on-site sanitation systems or other point sources, such as gas stations with leaking underground storage tanks, or leaking gutters.
The movement of water and dispersion in aquifers spread pollutants to a wider area, the advanced boundaries are often called the plume edges, which can then tangle with groundwater wells or sunlight into surface water such as seepage and springs, making water supplies unsafe to humans. and wildlife. Different mechanisms have an effect on the transport of pollutants, such as diffusion, adsorption, precipitation, decay, in ground water. The interaction of groundwater contamination with surface water was analyzed using a hydrological transport model.
The hazard of urban supply contamination is minimized by placing wells in deep groundwater and undeclared soils, and careful testing and monitoring of aquifer and potential pollution sources nearby.
Arsenic and fluoride
About a third of the world's population drink water from groundwater resources. Of this amount, about 10 percent, about 300 million people, get water from a highly polluted arsenic or fluoride groundwater resource. These trace elements originate mainly from natural sources with washing of rocks and sediments.
New method for identifying substances harmful to health
In 2008, the Swiss Aquatic Research Institute, Eawag, presented a new method in which hazard maps could be produced for geogenic toxic substances in groundwater. This provides an efficient way to determine which wells to test.
By 2016, the research group makes their knowledge available for free on the Groundwater Supply Management Platform GAP. It offers specialists worldwide the possibility to upload their own measurement data, visually display it and create a risk map for their chosen area. GAP also serves as a knowledge sharing forum to enable further development of methods to remove toxic substances from water.
Rule
United States
In the United States, laws on the ownership and use of ground water are generally state laws; however, groundwater arrangements to minimize groundwater pollution by both federal states and the Federal Environmental Protection Agency. Ownership and use of water rights usually follow one of three main systems:
- The Rule of Capture gives each landowner the ability to capture as much groundwater as they can, but they are not guaranteed the amount of water set. As a result, the owners of the well are not accountable to other landowners for taking water from their underground. State laws or regulations will often define "useful uses", and sometimes place other restrictions, such as prohibiting ground water extraction leading to a decline in neighboring property.
- Limited private ownership rights similar to riparian rights in the surface stream. The exact amount of ground water is based on the size of the surface area where each landowner gets the amount of water available. Once disconnected, the maximum amount of water rights is set, but the right can be reduced if the total amount of available water decreases as may occur during the drought. Landowners may sue others for infringing their groundwater rights, and water pumped for use on land takes preference over pumped water for use abroad.
- In November 2006, the Environmental Protection Agency issued the Ground Water Regulations in the Federal Register of the United States. The EPA is worried that the ground water system will be vulnerable to contamination from impurities. The point of the rule is to keep pathogenic microbes out of public water sources. The 2006 groundwater regulation was an amendment to the Safe Drinking Water Act of 1996.
Other rules in the United States include:
- Unreasonable Rules of Use (American Rules): This rule does not guarantee the owner of a certain amount of water, but allows unlimited extraction as long as the result does not improperly damage another well or aquifer system. This rule typically weighs heavily on historical usage and prevents new usages that interfere with previous usage.
- Groundwater surveillance of real estate property transactions in the US: In the US, in commercial real estate property transactions, both groundwater and soil are subject to monitoring. For brownfields sites (Stage I Site Environmental assessments are usually prepared, to investigate and disclose potential pollution problems. In the San Fernando Valley of California, the real estate contract for the transfer of property under the Santa Susana Field Laboratory (SSFL) and the east has a clause that frees the seller from responsibility for groundwater contamination due to the existing or future pollution of the Aquifer Valley.
India
In India, groundwater regulation is controlled and maintained by the central government and four organizations; 1) Central Water Commission, 2) Groundwater Center, 3) Central Ground Water Authority, 4) Central Pollution Control Agency.
Laws and Regulations on Groundwater India:
- In 2011, the Government of India drafted the Model Bill for Groundwater Management; this model chooses which state governments can enforce their laws on groundwater use and regulation.
- The Government of India created the National Water Framework Bill in 2013. The bill ensures that ground water in India is a public resource, and should not be exploited by the company through water privatization. The National Water Framework Bill allows everyone to access clean drinking water, on the right to clean drinking water under Article 21 of the 'Right to Life' in the Indian Constitution. The bill shows the desire of Indian states to have complete control over the groundwater contained in the aquifer. So far Andhra Pradesh, Assam, Bihar, Goa, Himachal Pradesh, Jammu & amp; Kashmir, Karnataka, Kerala, West Bengal, Telangana, Maharashtra, Lakshadweep, Puducherry, Chandigarh, Dadra & amp; Nagar Haveli is the only one who uses this bill.
- Section 7 (g) of the Covenant Act, 1882 stipulates that every landowner has the right to collect within its boundaries all underground water and on its surface which fails to pass within the prescribed channel.
- The 1882 Easement Act gives priority landowners on the ground and groundwater that is on their land and allows them to give or take as much as they want as long as water is in their land. This action prevents the government from enacting ground water regulation, allowing many landowners to privatize their groundwater and access it in the community area.
Canada
Most Canadians depend on groundwater use. In Canada, about 8.9 million people or 30% of the population of Canada, depend on ground water for domestic use and about two-thirds of these users live in rural areas.
- Under the Constitution Act, 1867 does not authorize the ground water to any of the Canadian government orders, therefore, the issue is largely under the jurisdiction of the province
- The Federal and Provincial Governments may share responsibilities when addressing agricultural, health, inter-provincial, and national water-related issues.
- Federal jurisdiction in various fields as boundary waters/boundaries, fisheries, navigation, and water in federal territory, First Nations reserves and in Territories.
- The federal territory of the groundwater when the aquifer crosses inter-provincial or international boundaries.
The large federal government groundwater initiative, is the development of a multi-barrier approach. A multi-barrier approach is a process system to prevent damage to drinking water from its source. Multi-delimiter consists of three main elements:
- Water protection source;
- Drinking drinking water; and
- Drinking water distribution system.
See also
References
External links
- The USGS Ground Office
- UK Groundwater Forum
- IGRAC, International Land Resource Assessment Center
- IAH, International Hydrogeological Association
- The Argoss Project from the British Geological Survey
Source of the article : Wikipedia
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