Saturday, February 27, 2010

Ras Sidr Hot Spring Artesian Well (part 2)

An artesian well allows water that has traveled through porous rock from a higher elevation to rise to the surface. This pump less well seems to defy gravity because the pressure that builds up between layers of rock gets relieved when the water finds a path to the open air. For nearly a thousand years, people have drilled wells to drink this cold, filtered water that doesn't need to be hauled up from the depths.

An aquifer provides the water source for an artesian well. This is the layer of permeable rock, like sandstone or, limestone that absorbs water from an inlet path at high elevation, such as the top of a mountain. The water source might be fed by snow melt or precipitation.

Porous stone is sandwiched between a top and bottom layer of an impermeable substance, like clay soil or shale rock. This keeps the water pressure high, so that at a point below the entryway of the flow there is enough pressure to bring the water up. Natural springs form in the same way when a gap in the impermeable rock, perhaps triggered by an earthquake, allows the water to rise to the surface.

Artesian wells are found all over the world. Many are found in the US, from Olympia, Washington, to Long Island, New York. The Great Artesian Basin, which provides fresh water to inland Australia, is the largest such basin in the world. Thousands of artesian wells have tapped into this aquifer.
Ras Sidr Hot spring is in fact an Artesian Well.
Entire cities have relied on giant underground aquifers to provide fresh, cold water when there are no above-ground rivers. In 1126, Carthusian monks in Artois France ( the term Artesian comes from Artois) used a rod with a sharp end, called a bore, to penetrate a layer of impermeable rock and create an artesian well. Their percussive drilling, just hammering on the end of the bore, broke through with sheer human force. The water that rose had percolated through the pores of the rock, so that many contaminants have been filtered out, and it proved safer to drink than standing or river water.

The well water found at Ras Sidr has been tested and was found to be 6.66 pH which is almost neutral, neither acid nor alkaline.
Testing conducted in 2008 by the Abdul Aziz University in Jeddah Saudi Arabia, found the water at Ras Sidr Artesian Well to be high in concentrations of Aragonite, Calcite, Dolomite, Quartz, Anhydrite, Gypsum, Chalcedony, Bromine, Calcium, Magnesium, Chlorine, Sodium, Potassium, Bromine, Sulphur Dioxide, Lithium, and Bicarbonate.
South Sinai Governorate has tapped the Ras Sidr Artesian Well and now allows for a continuous flow from an underground to ground level U shaped pipe which can be used to collect the purified water into bottles to take away. The pipe is situated North of the lake at the source and is coloured blue.

Artesian Well is described in full here:

What Is an Aquifer?
One of our most valuable resources is the water beneath our feet. Most of the time you can't even see it, and you may not even know it is there. Water (not groundwater) is held by molecular attraction and surrounds the surfaces of rock particles.
Different kinds of rocks have different porosity and permeability characteristics. Because of this, water does not move around the same way in all rocks. When water-bearing rocks readily transmit water to wells and springs, they are called aquifers. Wells can be drilled into the aquifers and water can be pumped out. Precipitation eventually adds water into the porous rock of the aquifer, which is known as recharging. The rate of recharge is not the same for all aquifers, though, and that must be considered when pumping water from a well. Pumping too much water too fast can draw down the water in an aquifer and may eventually cause a well to yield less and less water or even run dry. In fact, pumping your well too fast can even cause your neighbor's well to run dry if you both are pumping from the same aquifer.
Sometimes the porous rock layers become tilted in the Earth. There might be a confining layer of less porous rock both above and below the porous layer. This is an example of a confined aquifer. In this case, the rocks surrounding the aquifer confine the pressure in the porous rock and its water. If a well is drilled into the "pressurized" aquifer, the internal pressure might (depending on the ability of the rock to transport water) be enough to push the water up the well and up to the surface without the aid of a pump. Water can even flow completely out of the well. This type is called an artesian well. The pressure of water from an artesian well can be quite dramatic!

Artesian Aquifer -- an aquifer that has pressure built up inside. This pressure is the result of the recharge area of the aquifer being at a higher level than the rest of the aquifer region. The force of gravity pulls the higher water down, which creates extra pressure inside the aquifer. This is why artesian wells flow by themselves; the pressure forces the water out of the well.
Confining Bed -- a layer of ground that resists water penetration. This layer is typically finer textured and denser than the above layers of soil. Confining beds can keep water from seeping to unreachable depths but can also prevent water from reaching aquifers.
Consolidated Rock -- rock that contains very few holes or cracks for water to get through. An example of unconsolidated rock is gravel. Consolidated rock can serve as a confining bed.
Flowing Artesian Well -- a well that has penetrated into an artesian aquifer. Artesian aquifers have pressure built up within themselves. This pressure results from a portion of the aquifer being at a higher elevation as shown in the figure. The pressure is released when a well is bored into it. This causes the well to flow spontaneously.
Nonflowing Artesian Well -- a nonflowing artesian well occurs when the pressure is not great enough to force the water out of the well. In this diagram, this is apparent because the flowing artesian well is at a lower elevation than the non-flowing artesian well
Recharge Area -- an area that allows water to enter the aquifer. It is particularly vulnerable to any pollutants that could be in the water. Also, if pavement is constructed over the recharge area, less water can enter the aquifer. This could mean a water shortage to those people using the groundwater from the aquifer.
Spring -- occurs when the water table is higher than the ground surface. Pressure forces the water out of the land at a weak point that creates the spring.
Surface Water Stream or Pond -- caused by a high water table. Also, a high water table can result from a stream and pond in that area.
Water Table -- the level at which the water stays. It is the very top of the zone of saturation. A few centimeters above this level water can also be found due to capillary action. In the presence of a pumping well, the water table will drop around the well. This is called drawdown. Under some conditions, a perched water table may exist. This occurs when the water percolation is interrupted by another confining layer above the "main" one.
Water Table Aquifer -- an aquifer that supports the water table. The top limit to this aquifer is the water table itself.
Water Table Well -- a water table well is a well that only extends down into the water table aquifer.

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