Misplaced Pages

#486513

38-463: Mehdiganj has experienced a lack of water due to a lowered water table since about 2001. In 1999 a Coca-Cola bottling plant opened in Mehdiganj, and within a few years this factory has taken some or all of the blame from local people for causing the lack of water. There have been numerous protests by local people against this bottling plant. This Varanasi district location article

76-547: A desert climate often face physical water scarcity. Central Asia , West Asia , and North Africa are examples of arid areas. Economic water scarcity results from a lack of investment in infrastructure or technology to draw water from rivers, aquifers , or other water sources. It also results from weak human capacity to meet water demand. Many people in Sub-Saharan Africa are living with economic water scarcity. An important concern for hydrological ecosystems

114-529: A collection of 17 interlinked global goals designed to be a "blueprint to achieve a better and more sustainable future for all". Targets on fresh water conservation are included in SDG 6 (Clean water and sanitation) and SDG 15 (Life on land). For example, Target 6.4 is formulated as "By 2030, substantially increase water-use efficiency across all sectors and ensure sustainable withdrawals and supply of freshwater to address water scarcity and substantially reduce

152-570: A deeper aquifer has a lower permeable unit that confines the upward flow, then the water level in this aquifer may rise to a level that is greater or less than the elevation of the actual water table. The elevation of the water in this deeper well is dependent upon the pressure in the deeper aquifer and is referred to as the potentiometric surface , not the water table. The water table may vary due to seasonal changes such as precipitation and evapotranspiration . In undeveloped regions with permeable soils that receive sufficient amounts of precipitation,

190-402: A drinking water supply it remains vital to protect due to its ability to carry contaminants and pollutants from the land into lakes and rivers, which constitute a significant percentage of other people's freshwater supply. It is almost ubiquitous underground, residing in the spaces between particles of rock and soil or within crevices and cracks in rock, typically within 100 m (330 ft) of

228-428: A larger salt content. Freshwater habitats can be classified by different factors, including temperature, light penetration, nutrients, and vegetation. There are three basic types of freshwater ecosystems: Lentic (slow moving water, including pools , ponds , and lakes ), lotic (faster moving water, for example streams and rivers ) and wetlands (areas where the soil is saturated or inundated for at least part of

266-519: A single factor. Groundwater showed greater resilience to climate change than expected, and areas with an increasing threshold between 0.34 and 0.39 aridity index exhibited significant sensitivity to climate change. Land-use could affect infiltration and runoff processes. The years of most recharge coincided with the most precipitation anomalies, such as during El Niño and La Niña events. Three precipitation-recharge sensitivities were distinguished: in super arid areas with more than 0.67 aridity index, there

304-418: Is a stub . You can help Misplaced Pages by expanding it . Water table The water table is the upper surface of the zone of saturation . The zone of saturation is where the pores and fractures of the ground are saturated with groundwater , which may be fresh, saline, or brackish, depending on the locality. It can also be simply explained as the depth below which the ground is saturated. The water table

342-449: Is consumed through human activities than is naturally restored, this may result in reduced fresh water availability (or water scarcity ) from surface and underground sources and can cause serious damage to surrounding and associated environments. Water pollution also reduces the availability of fresh water. Where available water resources are scarce, humans have developed technologies like desalination and wastewater recycling to stretch

380-416: Is critical to the survival of all living organisms . Many organisms can thrive on salt water, but the great majority of vascular plants and most insects , amphibians , reptiles , mammals and birds need fresh water to survive. Fresh water is the water resource that is of the most and immediate use to humans. Fresh water is not always potable water , that is, water safe to drink by humans . Much of

418-452: Is extracted for human consumption. Agriculture uses roughly two thirds of all fresh water extracted from the environment. Fresh water is a renewable and variable, but finite natural resource . Fresh water is replenished through the process of the natural water cycle , in which water from seas, lakes, forests, land, rivers and reservoirs evaporates, forms clouds , and returns inland as precipitation. Locally, however, if more fresh water

SECTION 10

#1732783962487

456-411: Is groundwater that has remained in an aquifer for several millennia and occurs mainly in deserts . It is non-renewable by present-day rainfall due to its depth below the surface, and any extraction causes a permanent change in the water table in such regions. Most crops need a water table at a minimum depth. For some important food and fiber crops a classification was made because at shallower depths

494-483: Is particularly crucial in Africa, where water resources are often scarce and climate change poses significant challenges. Saline water in oceans , seas and saline groundwater make up about 97% of all the water on Earth . Only 2.5–2.75% is fresh water, including 1.75–2% frozen in glaciers , ice and snow, 0.5–0.75% as fresh groundwater. The water table is the level below which all spaces are filled with water, while

532-826: Is securing minimum streamflow , especially preserving and restoring instream water allocations . Fresh water is an important natural resource necessary for the survival of all ecosystems . Water pollution (or aquatic pollution) is the contamination of water bodies , with a negative impact on their uses. It is usually a result of human activities. Water bodies include lakes , rivers , oceans , aquifers , reservoirs and groundwater . Water pollution results when contaminants mix with these water bodies. Contaminants can come from one of four main sources. These are sewage discharges, industrial activities, agricultural activities, and urban runoff including stormwater . Water pollution may affect either surface water or groundwater . This form of pollution can lead to many problems. One

570-420: Is the degradation of aquatic ecosystems . Another is spreading water-borne diseases when people use polluted water for drinking or irrigation . Water pollution also reduces the ecosystem services such as drinking water provided by the water resource . Uses of water include agricultural , industrial , household , recreational and environmental activities. The Sustainable Development Goals are

608-411: Is the surface where the water pressure head is equal to the atmospheric pressure (where gauge pressure = 0). It may be visualized as the "surface" of the subsurface materials that are saturated with groundwater in a given vicinity. The groundwater may be from precipitation or from groundwater flowing into the aquifer. In areas with sufficient precipitation, water infiltrates through pore spaces in

646-537: The Amazon River . The atmosphere contains 0.04% water. In areas with no fresh water on the ground surface, fresh water derived from precipitation may, because of its lower density, overlie saline ground water in lenses or layers. Most of the world's fresh water is frozen in ice sheets . Many areas have very little fresh water, such as deserts . Water is a critical issue for the survival of all living organisms. Some can use salt water but many organisms including

684-663: The Green Sahara periods) and are not appreciably replenished under current climatic conditions - at least compared to drawdown, these aquifers form essentially non-renewable resources comparable to peat or lignite, which are also continuously formed in the current era but orders of magnitude slower than they are mined. Fresh water can be defined as water with less than 500 parts per million (ppm) of dissolved salts . Other sources give higher upper salinity limits for fresh water, e.g. 1,000 ppm or 3,000 ppm. Fresh water habitats are classified as either lentic systems , which are

722-514: The earth 's fresh water (on the surface and groundwater) is to a substantial degree unsuitable for human consumption without treatment . Fresh water can easily become polluted by human activities or due to naturally occurring processes, such as erosion. Fresh water makes up less than 3% of the world's water resources, and just 1% of that is readily available. About 70% of the world's freshwater reserves are frozen in Antarctica . Just 3% of it

760-443: The aquifer and the permeability of the material. The water table does not always mimic the topography due to variations in the underlying geological structure (e.g., folded, faulted, fractured bedrock). A perched water table (or perched aquifer) is an aquifer that occurs above the regional water table. This occurs when there is an impermeable layer of rock or sediment ( aquiclude ) or relatively impermeable layer ( aquitard ) above

798-494: The area above this level, where spaces in the rock and soil contain both air and water, is known as the unsaturated zone. The water in this unsaturated zone is referred to as soil moisture. Below the water table, the entire region is known as the saturated zone, and the water in this zone is called groundwater. Groundwater plays a crucial role as the primary source of water for various purposes including drinking, washing, farming, and manufacturing, and even when not directly used as

SECTION 20

#1732783962487

836-421: The available supply further. However, given the high cost (both capital and running costs) and - especially for desalination - energy requirements, those remain mostly niche applications. A non-sustainable alternative is using so-called " fossil water " from underground aquifers . As some of those aquifers formed hundreds of thousands or even millions of years ago when local climates were wetter (e.g. from one of

874-418: The capillary effect ( capillary fringe ) in soils , sediments and other porous media . In the aquifer, groundwater flows from points of higher pressure to points of lower pressure, and the direction of groundwater flow typically has both a horizontal and a vertical component. The slope of the water table is known as the “hydraulic gradient”, which depends on the rate at which water is added to and removed from

912-463: The crop suffers a yield decline. A water table close to the surface affects excavation, drainage, foundations, wells and leach fields (in areas without municipal water and sanitation), and more. When excavation occurs near enough to the water table to reach its capillary action, groundwater must be removed during construction. This is conspicuous in Berlin , which is built on sandy, marshy ground, and

950-535: The freshwater flow to be measurably contaminated both by insoluble solids but also by the soluble components of those soils. Significant quantities of iron may be transported in this way including the well-documented transfer of iron-rich rainfall falling in Brazil derived from sand-storms in the Sahara in north Africa . In Africa, it was revealed that groundwater controls are complex and do not correspond directly to

988-547: The great majority of higher plants and most mammals must have access to fresh water to live. Some terrestrial mammals, especially desert rodents , appear to survive without drinking, but they do generate water through the metabolism of cereal seeds, and they also have mechanisms to conserve water to the maximum degree. Freshwater ecosystems are a subset of Earth's aquatic ecosystems . They include lakes , ponds , rivers , streams , springs , bogs , and wetlands . They can be contrasted with marine ecosystems , which have

1026-435: The main water table/aquifer but below the land surface. If a perched aquifer's flow intersects the surface, at a valley wall, for example, the water is discharged as a spring . On low-lying oceanic islands with porous soil, freshwater tends to collect in lenticular pools on top of the denser seawater intruding from the sides of the islands. Such an island's freshwater lens, and thus the water table, rises and falls with

1064-413: The others as well. Water scarcity (closely related to water stress or water crisis) is the lack of fresh water resources to meet the standard water demand. There are two types of water scarcity. One is physical. The other is economic water scarcity . Physical water scarcity is where there is not enough water to meet all demands. This includes water needed for ecosystems to function. Regions with

1102-421: The sea if windy conditions have lifted drops of seawater into the rain-bearing clouds. This can give rise to elevated concentrations of sodium , chloride , magnesium and sulfate as well as many other compounds in smaller concentrations. In desert areas, or areas with impoverished or dusty soils, rain-bearing winds can pick up sand and dust and this can be deposited elsewhere in precipitation and causing

1140-497: The soil, passing through the unsaturated zone. At increasing depths, water fills in more of the pore spaces in the soils, until a zone of saturation is reached. Below the water table, in the phreatic zone (zone of saturation), layers of permeable rock that yield groundwater are called aquifers . In less permeable soils, such as tight bedrock formations and historic lakebed deposits, the water table may be more difficult to define. “Water table” and “ water level ” are not synonymous. If

1178-420: The stillwaters including ponds , lakes, swamps and mires ; lotic which are running-water systems; or groundwaters which flow in rocks and aquifers . There is, in addition, a zone which bridges between groundwater and lotic systems, which is the hyporheic zone , which underlies many larger rivers and can contain substantially more water than is seen in the open channel. It may also be in direct contact with

Mehdiganj - Misplaced Pages Continue

1216-666: The surface, and soil moisture, and less than 0.01% of it as surface water in lakes , swamps and rivers . Freshwater lakes contain about 87% of this fresh surface water, including 29% in the African Great Lakes , 22% in Lake Baikal in Russia, 21% in the North American Great Lakes , and 14% in other lakes. Swamps have most of the balance with only a small amount in rivers, most notably

1254-479: The tides. In some regions, for example, Great Britain or California , winter precipitation is often higher than summer precipitation and so the groundwater storage is not fully recharged in summer. Consequently, the water table is lower during the summer. This disparity between the level of the winter and summer water table is known as the "zone of intermittent saturation", wherein the water table will fluctuate in response to climatic conditions. Fossil water

1292-469: The time). Freshwater ecosystems contain 41% of the world's known fish species. The increase in the world population and the increase in per capita water use puts increasing strains on the finite resources availability of clean fresh water. The response by freshwater ecosystems to a changing climate can be described in terms of three interrelated components: water quality, water quantity or volume, and water timing. A change in one often leads to shifts in

1330-657: The underlying underground water. The original source of almost all fresh water is precipitation from the atmosphere , in the form of mist , rain and snow . Fresh water falling as mist, rain or snow contains materials dissolved from the atmosphere and material from the sea and land over which the rain bearing clouds have traveled. The precipitation leads eventually to the formation of water bodies that humans can use as sources of freshwater: ponds , lakes , rainfall , rivers , streams , and groundwater contained in underground aquifers . In coastal areas fresh water may contain significant concentrations of salts derived from

1368-976: The water table is generally 2 meters below the surface. Pink and blue pipes can often be seen carrying groundwater from construction sites into the Spree river (or canals). Freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids . The term excludes seawater and brackish water , but it does include non-salty mineral-rich waters , such as chalybeate springs. Fresh water may encompass frozen and meltwater in ice sheets , ice caps , glaciers , snowfields and icebergs , natural precipitations such as rainfall , snowfall , hail / sleet and graupel , and surface runoffs that form inland bodies of water such as wetlands , ponds , lakes , rivers , streams , as well as groundwater contained in aquifers , subterranean rivers and lakes . Water

1406-409: The water table typically slopes toward rivers that act to drain the groundwater away and release the pressure in the aquifer. Springs , rivers , lakes and oases occur when the water table reaches the surface. Groundwater entering rivers and lakes accounts for the base-flow water levels in water bodies. Within an aquifer, the water table is rarely horizontal, but reflects the surface relief due to

1444-461: Was constant recharge with little variation with precipitation; in most sites (arid, semi-arid, humid), annual recharge increased as annual precipitation remained above a certain threshold; and in complex areas down to 0.1 aridity index (focused recharge), there was very inconsistent recharge (low precipitation but high recharge). Understanding these relationships can lead to the development of sustainable strategies for water collection. This understanding

#486513