Which way does groundwater flow

Do you think it is true? Actually, it is pretty much a myth. Even though there are some caverns, lava and ice tubes, and horizontal springs that can carry water, the vast majority of underground water occupies the spaces between rocks and subsurface material. Generally, water underground is more like water in a sponge.

It occupies the spaces between soil and rock particles. At a certain depth below the land surface, the spaces between the soil and rock particles can be totally filled with water, resulting in an aquifer from which groundwater can be pumped and used by people. Some of the precipitation that falls onto the land infiltrates into the ground to become groundwater. If the water meets the water table below which the soil is saturated , it can move both vertically and horizontally.

Water moving downward can also meet more dense and water-resistant non-porous rock and soil, which causes it to flow in a more horizontal fashion, generally towards streams, the ocean , or deeper into the ground.

If groundwater wants to be a member in good standing of the water cycle, then it can't be totally static and stay where it is.

As the diagram shows, the direction and speed of groundwater movement is determined by the various characteristics of aquifers and confining layers of subsurface rocks which water has a difficult time penetrating in the ground.

Water moving below ground depends on the permeability how easy or difficult it is for water to move and on the porosity the amount of open space in the material of the subsurface rock.

If the rock has characteristics that allow water to move relatively freely through it, then groundwater can move significant distances in a number of days. But groundwater can also sink into deep aquifers where it takes thousands of years to move back into the environment, or even go into deep groundwater storage , where it might stay for much longer periods. If an aquifer is under enough pressure, an artesian well tapping the aquifer can result in pressurized water shooting above the land surface.

Bottled water is a very popular beverage nowadays all over the world. Sometimes it is because the local drinking water is of lower quality and sometimes it is just a convenience. Some bottled water is advertised as "artesian well water". Is the water really any different than other groundwater? Artesian well water is not really different from non-artesian well water - but it comes to the surface in a different manner.

In the diagram above, you can see that there are unconfined and confined aquifers in the ground. The confinement of water in an aquifer, which can result in pressure, determines if water coming from it is artesian or not. Wells drilled into confined aquifers can yield artesian water. So, in what way is bottled artesian well water different from other well water? Mainly, the company that bottles it doesn't have to go to the expense of installing a pump in their well.

As these charts show, even though the amount of water locked up in groundwater is a small percentage of all of Earth's water , it represents a large percentage of total freshwater on Earth. The pie chart shows that about 1. As the bar chart shows, about 5,, cubic miles mi 3 , or 23,, cubic kilometers km 3 , of groundwater exist on Earth. About 54 percent is saline, with the remaining 2,, mi 3 10,, km 3 , about 46 percent, being freshwater.

Source: Gleick, P. In Encyclopedia of Climate and Weather, ed. Do you think you know about groundwater? Quiz icon made by mynamepong from www. Earth's water is always in movement, and the natural water cycle, also known as the hydrologic cycle, describes the continuous movement of water on, above, and below the surface of the Earth. Water is always changing states between liquid, vapor, and ice, with these processes happening in the blink of an eye and over millions of years.

The air is full of water, even if you can't see it. Water falling on the ground surface as precipitation rain, snow, hail, fog, etc. The water in the unsaturated zone may be used by plants transpiration , evaporate from the soil evaporation , or continue past the root zone and flow downward to the water table, where it recharges the groundwater.

A cross-section of a typical hillside with an unconfined aquifer is illustrated in Figure In areas with topographic relief, the water table generally follows the land surface, but tends to come closer to surface in valleys, and intersects the surface where there are streams or lakes. In this case, most of the hillside forms the recharge area , where water from precipitation flows downward through the unsaturated zone to reach the water table. The area at the stream or lake to which the groundwater is flowing is a discharge area.

What makes water flow from the recharge areas to the discharge areas? Recall that water is flowing in pores where there is friction, which means it takes work to move the water. There is also some friction between water molecules themselves, which is determined by the viscosity.

Water has a low viscosity, but friction is still a factor. All flowing fluids are always losing energy to friction with their surroundings. Water will flow from areas with high energy to those with low energy.

Recharge areas are at higher elevations, where the water has high gravitational energy. It was energy from the sun that evaporated the water into the atmosphere and lifted it up to the recharge area. The water loses this gravitational energy as it flows from the recharge area to the discharge area. In Figure The water table is higher under the recharge area 90 m and lower at the discharge area 82 m. Imagine how much work it would be to lift water 8 m high in the air. That is the energy that was lost to friction as the groundwater flowed from the top of the hill to the stream.

The situation gets a lot more complicated in the case of confined aquifers, but they are important sources of water so we need to understand how they work. Then browse over free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

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Create your free OpenLearn profile. Course content Course content. Groundwater Start this free course now. Free course Groundwater. Figure 8 Direction of groundwater flow in the Triassic sandstones in Nottinghamshire.

This figure covers the same area as Figure 5. The groundwater flows at right-angles to the water table contours, i. Figure 9 The direction of flow of groundwater at depth is not parallel to the water table; instead, water moves in a curved path, converging towards a point of discharge. In a the rock is uniformly permeable, and the water discharges into streams in the valleys; it may approach the stream from below.

In b the hill is capped by a permeable rock which is underlain by an impermeable rock. The water is diverted laterally by the impermeable rock, and springs result where the boundary between the permeable and impermeable rocks intersects the ground surface. Figure 10 The water table is drawn down into a cone of depression around a pumped well.

The diameter of the borehole is exaggerated. Figure 11 A cross-section illustrating the relationship between fresh groundwater and saline groundwater at a coast.

The vertical scale is exaggerated. The contour values are chloride concentrations in grams per litre. The Intermediate values result from the mixing of seawater and fresh water. Figure 13 Fresh groundwater and saline groundwater below an island. A lens-shaped body of fresh water occurs below the island.