A spring is a point at which water flows from an aquifer to the Earth's surface. It is a component of the hydrosphere.
A spring may be the result of karst topography where surface water has infiltrated the Earth's surface (recharge area), becoming part of the area groundwater. The groundwater then travels through a network of cracks and fissures—openings ranging from intergranular spaces to large caves. The water eventually emerges from below the surface, in the form of a karst 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 are artesian 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 of volcanic activity. The result can be water at elevated temperature such as a hot spring.
The action of the groundwater continually dissolves permeable bedrock such as limestone and dolomite, creating vast cave systems.
Spring discharge, or resurgence, 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, and losing streams. In some cases entire creeks seemingly disappear as the water sinks into the ground via the stream bed. Grand Gulf State Park in Missouri 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 of Mammoth Spring in Arkansas. Human activity may also affect a spring's discharge—withdrawal of groundwater reduces the water pressure in an aquifer, decreasing the volume of flow.
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 as Florida where there are at least 27 known to be that size; the Missouri and Arkansas Ozarks, which contain 10 known of first-magnitude; and 11 more in the Thousand Springs area along the Snake River in Idaho. The scale for spring flow is as follows:
|Magnitude||Flow (ft3/s, gal/min, pint/min)||Flow (L/s)|
|1st magnitude||> 100 ft3/s||2800 L/s|
|2nd magnitude||10 to 100 ft3/s||280 to 2800 L/s|
|3rd magnitude||1 to 10 ft3/s||28 to 280 L/s|
|4th magnitude||100 US gal/min to 1 ft3/s (448 US gal/min)||6.3 to 28 L/s|
|5th magnitude||10 to 100 gal/min||0.63 to 6.3 L/s|
|6th magnitude||1 to 10 gal/min||63 to 630 mL/s|
|7th magnitude||2 pint to 1 gal/min||8 to 63 mL/s|
|8th magnitude||Less than 1 pint/min||8 mL/s|
|0 magnitude||no flow (sites of past/historic flow)|
Minerals become dissolved in the water as it moves through the underground rocks. This may give the water flavor and even carbon dioxide bubbles, depending on the nature of the geology through which it passes. This is why spring water is often bottled and sold as mineral water, although the term is often the subject of deceptive advertising. 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 dissolved sodium salts, mostly sodium carbonate, are called 'soda springs'. Many resorts have developed around mineral springs and are known as spa towns.
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 or tannins will have an orange color.
In parts of the United States a stream carrying the outflow of a spring to a nearby primary stream may be called a spring branch or run. Groundwater tends to maintain a relatively long-term average temperature of its aquifer; so flow from a spring may be cooler than a summer day, but remain unfrozen in the winter. The cool water of a spring and its branch may harbor species such as certain trout that are otherwise ill-suited to a warmer local climate.
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Springs have been used for a variety of human needs including drinking water, domestic water supply, irrigation, mills, navigation, and electricity generation. Other modern uses include recreational activities such as fishing, swimming, and floating; therapy; water for livestock; fish hatcheries; and supply for bottled mineral water.
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A sacred spring, or holy well, is a small body of water emerging from underground and revered either in a Christian, pagan or other religious context, sometimes both.[ citation needed ] The lore and mythology of ancient Greece was replete with sacred and storied springs—notably, the Corycian, Pierian and Castalian. In medieval Europe, holy wells were frequently pagan sacred sites that later became Christianized. 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 local folklore. This can take the form of a particular name, an associated legend, the attribution of healing qualities to the water through the numinous presence of its guardian spirit or Christian saint, or a ceremony or ritual centred on the well site. In Christian legend, the spring water is often said to have been made to flow by the action of a saint, a familiar theme especially in the hagiography of Celtic saints.
An aquifer is an underground layer of water-bearing permeable rock, rock fractures or unconsolidated materials. Groundwater can be extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology. Related terms include aquitard, which is a bed of low permeability along an aquifer, and aquiclude, which is a solid, impermeable area underlying or overlying an aquifer. If the impermeable area overlies the aquifer, pressure could cause it to become a confined aquifer.
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 water.
A drainage basin is any area of land where precipitation collects and drains off into a common outlet, such as into a river, bay, or other body of water. The drainage basin includes all the surface water from rain runoff, snowmelt, and nearby streams that run downslope towards the shared outlet, as well as the groundwater underneath the earth's surface. Drainage basins connect into other drainage basins at lower elevations in a hierarchical pattern, with smaller sub-drainage basins, which in turn drain into another common outlet.
Groundwater is the water present beneath Earth's surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock become completely saturated with water is called the water table. Groundwater is recharged from the surface; it may discharge from the surface naturally at springs and seeps, and can form oases or wetlands. Groundwater is also often withdrawn for agricultural, municipal, and industrial use by constructing and operating extraction wells. The study of the distribution and movement of groundwater is hydrogeology, also called groundwater hydrology.
The vadose zone, also termed the unsaturated zone, is the part of Earth between the land surface and the top of the phreatic zone, the position at which the groundwater is at atmospheric pressure. Hence, the vadose zone extends from the top of the ground surface to the water table.
In water-related science and engineering, there are two similar but distinct definitions in use for the word drawdown:
The Floridan aquifer system, composed of the Upper and Lower Floridan aquifers, is a sequence of Paleogene carbonate rock which spans an area of about 100,000 square miles in the southeastern United States. It underlies the entire state of Florida and parts of Alabama, Georgia, Mississippi, and South Carolina.
The Edwards Aquifer is one of the most prolific artesian aquifers in the world. Located on the eastern edge of the Edwards Plateau in the U.S. state of Texas, it is the source of drinking water for two million people, and is the primary water supply for agriculture and industry in the aquifer's region. In addition, the Edwards Aquifer feeds the Comal and San Marcos springs, provides springflow for recreational and downstream uses in the Nueces, San Antonio, Guadalupe, and San Marcos river basins, and is home to several unique and endangered species.
A losing stream, disappearing stream, influent stream or sinking river is a stream or river that loses water as it flows downstream. The water infiltrates into the ground recharging the local groundwater, because the water table is below the bottom of the stream channel. This is the opposite of a more common gaining stream which increases in water volume farther down stream as it gains water from the local aquifer.
Streamflow, or channel runoff, is the flow of water in streams, rivers, and other channels, and is a major element of the water cycle. It is one component of the runoff of water from the land to waterbodies, the other component being surface runoff. Water flowing in channels comes from surface runoff from adjacent hillslopes, from groundwater flow out of the ground, and from water discharged from pipes. The discharge of water flowing in a channel is measured using stream gauges or can be estimated by the Manning equation. The record of flow over time is called a hydrograph. Flooding occurs when the volume of water exceeds the capacity of the channel.
Groundwater recharge or deep drainage or deep percolation is a hydrologic process, where water moves downward from surface water to groundwater. Recharge is the primary method through which water enters an aquifer. This process usually occurs in the vadose zone below plant roots and, is often expressed as a flux to the water table surface. Groundwater recharge also encompasses water moving away from the water table farther into the saturated zone. Recharge occurs both naturally and through anthropogenic processes, where rainwater and or reclaimed water is routed to the subsurface.
Surficial aquifers are shallow aquifers typically less than 50 feet (15 m) thick, but larger surficial aquifers of about 60 feet (18 m) have been mapped. They mostly consist of unconsolidated sand enclosed by layers of limestone, sandstone or clay and the water is commonly extracted for urban use. The aquifers are replenished by streams and from precipitation and can vary in volume considerably as the water table fluctuates. Being shallow, they are susceptible to contamination by fuel spills, industrial discharge, landfills, and saltwater. Parts of southeastern United States are dependent on surficial aquifers for their water supplies.
Overdrafting is the process of extracting groundwater beyond the equilibrium yield of the aquifer.
Subsurface flow, in hydrology, is the flow of water beneath earth's surface as part of the water cycle.
A seep or flush is a moist or wet place where water, usually groundwater, reaches the earth's surface from an underground aquifer.
Groundwater-Dependent Ecosystems are ecosystems that rely upon groundwater for their continued existence. Groundwater is water that has seeped down beneath Earth's surface and has come to reside within the pore spaces in soil and fractures in rock, this process can create water tables and aquifers, which are large storehouses for groundwater. An ecosystem is a community of living organisms interacting with the nonliving aspects of their environment. With a few exceptions, the interaction between various ecosystems and their respective groundwater is a vital yet poorly understood relationship, and their management is not nearly as advanced as in-stream ecosystems.
Kissingen Spring was a natural spring formerly flowing in Polk County, Southwest Florida. It was also a venue for recreation until it dried up in 1950. Hundreds of wells drilled into the Floridan Aquifer may have caused the demise of the springs. Its site is located near the northern end of Peace River, approximately 3/4 mile east of U.S. Highway 17 and 4 miles south of Florida SR 60 / south of Bartow.
The Willamette Lowland basin-fill aquifer is 31,000 km2, 12,000 square mile aquifer underlying the region of Oregon and parts of Washington (state) between the Oregon Coast Range and the Cascade Range. The aquifer shares a name with the local river, the Willamette River, originating from a Clackamas Chinook word. The "mette" of Willamette was used by the Clackamas to mean water or river. The Willamette valley is home to 70% of Oregon's population, with the aquifer supplying water for agricultural, domestic, and industrial purposes. Reported in 2005, the total water use from the aquifer was 1.6 hm3 per day, with 58% going to irrigation, 24% to public supply, and 18% to industrial use. In general, the aquifer withdraw is sufficiently compensated in the long term by recharge through precipitation, however regions of the aquifer have shown long term declines, including that regions underlain by the Columbia River basalt unit. However, during the dry season from June-September, withdrawals from the aquifer result is significant seasonal variations in the ground water table height, changing by more than 60 ft. In the state of Oregon, all water is publicly owned and maintenance and protection of water is done by the Oregon Water Resources Department and the Oregon Water Resources Commission. However, local governments can provide land use permits for aquifer use, notably, use for new rural residences.
Mud Hole Spring is an unusual warm-water, submarine discharge of water off the southwestern Gulf Coast of Florida, at, approximately 18.5 kilometres (11.5 mi) south of the Sanibel Island Light and Lee County, Florida. It discharges geothermally warmed and turbid water from the sea floor.
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