On an average day nearly 303 million US gallons (1,150,000 m3) of water flow fromBig Spring inMissouri at a rate of 469 cubic feet per second (13.3 m3/s).Grand Prismatic Spring, Yellowstone National Park, Wyoming
Aspring is a natural exit point at whichgroundwater emerges from anaquifer and flows across the ground surface assurface water. It is a component of thehydrosphere, as well as a part of thewater cycle. Springs have long been important forhumans as a source offresh water, especially inarid regions which have relatively little annualrainfall.
Springs are driven out onto the surface by various natural forces, such asgravity andhydrostatic pressure. A spring produced by the emergence ofgeothermally heated groundwater is known as ahot spring. Theyield of spring water varies widely from avolumetric flow rate of nearly zero to more than 14,000 litres per second (490 cu ft/s) for the biggest springs.[1]
Springs are formed whengroundwater flows onto the surface. This typically happens when the water table reaches above the surface level, or if the terraindepresses sharply. Springs may also be formed as a result ofkarst topography, aquifers orvolcanic activity. Springs have also been observed on theocean floor, spewing warmer, low-salinity water directly into the ocean.[2]
Springs formed as a result of karst topography createkarst springs, in which ground water travels through a network of cracks and fissures—openings ranging from intergranular spaces to largecaves, later emerging in a spring.
The forcing of the spring to the surface can be the result of a confined aquifer in which the recharge area of the spring water table rests at a higher elevation than that of the outlet. Spring water forced to the surface by elevated sources areartesian wells. This is possible even if the outlet is in the form of a 300-foot-deep (91 m) cave. In this case the cave is used like a hose by the higher elevated recharge area of groundwater to exit through the lower elevation opening.
Non-artesian springs may simply flow from a higher elevation through the earth to a lower elevation and exit in the form of a spring, using the ground like a drainage pipe. Still other springs are the result of pressure from an underground source in the earth, in the form ofvolcanic ormagma activity. The result can be water at elevated temperature and pressure, i.e.hot springs andgeysers.
Depression springs occur along a depression, such as the bottom ofalluvial valleys, basins, orvalleys made of highly permeable materials.[4]
Contact springs, which occur along the side of a hill or mountain, are created when thegroundwater is underlaid by an impermeable layer of rock or soil known as an aquiclude or aquifuge[4]
Fracture, or joint occur when groundwater running along an impermeable layer of rock meets a crack (fracture) or joint in the rock.[4]
Tubular springs occur when groundwater flows from circular fissures such as those found in caverns (solution tubular springs) or lava tubular springs found inlava tube caves.[5][6]
Artesian springs typically occur at the lowest point in a given area. An artesian spring is created when the pressure for the groundwater becomes greater than the pressure from the atmosphere. In this case the water is pushed straight up out of the ground.[7]
Wonky holes are freshwater submarine exit points for coral and sediment-covered, sediment-filled old river channels.[8]
Thermal springs are heated bygeothermal activity; they have a water temperature significantly higher than the mean air temperature of the surrounding area.[10] Geysers are a type of hot spring where steam is created underground by trapped superheated groundwater resulting in recurring eruptions of hot water and steam.[6]
Carbonated springs, such asSoda Springs Geyser, are springs that emit naturally occurring carbonated water, due to dissolved carbon dioxide in the water content. They are sometimes called boiling springs or bubbling springs.[11]
Spring discharge, orresurgence, is determined by the spring's recharge basin. Factors that affect the recharge include the size of the area in which groundwater is captured, the amount of precipitation, the size of capture points, and the size of the spring outlet. Water may leak into the underground system from many sources including permeable earth, sinkholes, andlosing streams. In some cases entirecreeks seemingly disappear as the water sinks into the ground via the stream bed.Grand Gulf State Park inMissouri is an example of an entire creek vanishing into the groundwater system. The water emerges 9 miles (14 km) away, forming some of the discharge ofMammoth Spring inArkansas. Human activity may also affect a spring's discharge—withdrawal of groundwater reduces the water pressure in an aquifer, decreasing the volume of flow.[13]
Fontaine de Vaucluse or Spring of Vaucluse in France discharges about 470 million US gallons (1,800,000 m3) of water per day at a rate of 727 cu ft (20.6 m3) per second.
Springs fall into three general classifications: perennial (springs that flow constantly during the year); intermittent (temporary springs that are active after rainfall, or during certain seasonal changes); and periodic (as in geysers that vent and erupt at regular or irregular intervals).[5]
Springs are often classified by the volume of the water they discharge. The largest springs are called "first-magnitude", defined as springs that discharge water at a rate of at least 2800 liters or 100 cubic feet (2.8 m3) of water per second. Some locations contain many first-magnitude springs, such asFlorida where there are at least 27 known to be that size; theMissouri andArkansasOzarks, which contain 10[14][13] known of first-magnitude; and 11[15] more in theThousand Springs area along theSnake River inIdaho. The scale for spring flow is as follows:
Minerals become dissolved in the water as it moves through the undergroundrocks. This mineral content is measured astotal dissolved solids (TDS). This may give the water flavor and evencarbon dioxide bubbles, depending on the nature of thegeology through which it passes. This is why spring water is often bottled and sold asmineral water, although the term is often the subject ofdeceptiveadvertising. Mineral water contains no less than 250 parts per million (ppm) of tds. Springs that contain significant amounts of minerals are sometimes called 'mineral springs'. (Springs without such mineral content, meanwhile, are sometimes distinguished as 'sweet springs'.) Springs that contain large amounts of dissolvedsodiumsalts, mostlysodium carbonate, are called 'soda springs'. Many resorts have developed around mineral springs and are known asspa towns. Mineral springs are alleged to have healing properties. Soaking in them is said to result in the absorption of the minerals from the water. Some springs containarsenic levels that exceed the 10 ppbWorld Health Organization (WHO) standard fordrinking water.[16] Where such springs feed rivers they can also raise the arsenic levels in the rivers above WHO limits.[16]
Water from springs is usually clear. However, some springs may be colored by the minerals that are dissolved in the water. For instance, water heavy with iron ortannins will have an orange color.[3]
In parts of the United States astream carrying the outflow of a spring to a nearby primary stream may be called aspring branch,spring creek, or run. Groundwater tends to maintain a relatively long-term average temperature of its aquifer; so flow from a spring may be cooler than other sources on a summer day, but remain unfrozen in the winter. The cool water of a spring and its branch may harbor species such as certaintrout that are otherwise ill-suited to a warmer localclimate.
Sulfur springs contain a high level of dissolvedsulfur or hydrogen sulfide in the water. Historically they have been used to alleviate the symptoms of arthritis and other inflammatory diseases.[17][18]
Springs have been used for a variety of human needs - including drinking water, domestic water supply, irrigation,mills, navigation, andelectricity generation. Modern uses include recreational activities such as fishing, swimming, and floating;therapy; water for livestock; fish hatcheries; and supply for bottledmineral water or bottled spring water. Springs have taken on a kind of mythic quality in that some people falsely believe that springs are always healthy sources of drinking water. They may or may not be. One must take a comprehensive water quality test to know how to use a spring appropriately, whether for a mineral bath or drinking water. Springs that are managed as spas will already have such a test.
Springs are often used as sources for bottled water.[22] When purchasing bottled water labeled as spring water one can often find the water test for that spring on the website of the company selling it.
Springs have been used as sources of water for gravity-fed irrigation of crops.[23] Indigenous people of theAmerican Southwest built spring-fedacequias that directed water to fields through canals. The Spanish missionaries later used this method.[24][25]
A sacred spring, or holy well, is a small body of water emerging from underground and revered in some religious context:Christian and/orpagan and/or other.[26][27] The lore and mythology ofancient Greece was replete with sacred and storied springs—notably, theCorycian,Pierian andCastalian springs. In medieval Europe, pagan sacred sites frequently becameChristianized as holy wells. The term "holy well" is commonly employed to refer to any water source of limited size (i.e., not a lake or river, but including pools and natural springs and seeps), which has some significance in localfolklore. This can take the form of a particular name, an associatedlegend, the attribution ofhealing qualities to the water through thenuminous presence of its guardian spirit or of aChristian saint, or a ceremony orritual centered on the well site.Christian legends often recount how the action of a saint caused a spring's water to flow - a familiar theme, especially in thehagiography ofCeltic saints.[citation needed]
The geothermally heated groundwater that flows from thermal springs is greater than human body temperature, usually in the range of 45–50 °C (113–122 °F), but they can be hotter.[6] Those springs with water cooler than body temperature but warmer than air temperature are sometimes referred to as warm springs.[28]
Hot springs or geothermal springs have been used forbalneotherapy, bathing, and relaxation for thousands of years. Because of the folklore surrounding hot springs and their claimed medical value, some have become tourist destinations and locations ofphysical rehabilitation centers.[29][30]
Natural spring in Pennsylvania where runoff flows from above down through grass and rocks
Hot springs have been used as a heat source for thousands of years. In the 20th century, they became a renewable resource of geothermal energy for heating homes and buildings.[29] The city ofBeppu, Japan contains 2,217 hot spring well heads that provide the city with hot water.[31] Hot springs have also been used as a source of sustainable energy for greenhouse cultivation and the growing of crops and flowers.[32]
Springs have been represented in culture through art, mythology, and folklore throughout history. TheFountain of Youth is a mythical spring which was said to restore youth to anyone who drank from it.[34] It has been claimed that the fountain is located inSt. Augustine, Florida, and was discovered byJuan Ponce de León in 1513. However, it has not demonstrated the power to restore youth, and most historians dispute the veracity of Ponce de León's discovery.[35][36]
Pythia, also known as theOracle at Delphi was the high priestess of theTemple of Apollo. She delivered prophesies in a frenzied state of divine possession that were "induced by vapours rising from a chasm in the rock". It is believed that the vapors were emitted from the Kerna spring at Delphi.[37][38]
The Greek myth ofNarcissus describes a young man who fell in love with his reflection in the still pool of a spring. Narcissus gazed into "an unmuddied spring, silvery from its glittering waters, which neither shepherds nor she-goats grazing on the mountain nor any other cattle had touched, which neither bird nor beast nor branch fallen from a tree had disturbed." (Ovid)[39]
The early 20th century American photographer,James Reuel Smith created a comprehensive series of photographs documenting the historical springs of New York City before they were capped by the city after the advent of the municipal water system.[40] Smith later photographed springs in Europe leading to his book,Springs and Wells in Greek and Roman Literature, Their Legends and Locations (1922).[41]
The Chinese cityJinan is known as "a City of Springs" (Chinese: 泉城), because of its 72 spring attractions and numerous micro spring holes spread over the city centre.[43][44]
John William Waterhouse Echo And Narcissus, 1903
Lucas Cranach,Der Jungbrunnen (Fountain of Youth), 1546
^Westbrook, Cherie J. (2017). "Heads Above Water: The Inside Story of the Edwards Aquifer Recovery Implementation Program by Robert L. Gulley".Great Plains Research.27 (2): 143.doi:10.1353/gpr.2017.0022.ISSN2334-2463.S2CID133972692.
^Horstman, Mark (18 May 2006)."Wonky Holes".Catalyst transcript. Australian Broadcasting Corporation.Archived from the original on 19 April 2019. Retrieved17 April 2019.
^Whittow, John (1984).Dictionary of Physical Geography. London: Penguin. p. 291.ISBN0-14-051094-X.
^Clement, Christopher Ohm; Moseley, Michael E. (1991). "The Spring-Fed Irrigation System of Carrizal, Peru: A Case Study of the Hypothesis of Agrarian Collapse".Journal of Field Archaeology.18 (4):425–443.doi:10.1179/009346991791549059.
^Ray, Celeste (2011). "The Sacred and the Body Politic at Ireland's Holy Wells".International Social Science Journal.62 (205/206):271–85.doi:10.1111/issj.12000.
^Byrne, Garreth (2002). "Holy Wells in Britain and Ireland".Contemporary Review.280 (1636): 295 – viaEBSCOhost.
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