Foggaras are underground galleries that collect the water that is in depth and transport to the surface. These nearly horizontal underground pipes carry water from the aquifer to the oasis, thanks to a slight tilt of one or two millimeters per meter.
The gentle slope of the galleries slows the flow of water, avoiding friction with the ground and erosion. To make the system work foggaras, oases to be found in depressions or valleys, or at the foot of a hill, that is, below the water table. The oasis of Adrar are located below the plateau Tadmit where ground water emerges. This ingenious method gravity to transport water throughout the year.
The materials used for the construction of the surrounding foggaras come: Blocks of stone are cut by a conglomerate of clay and straw, and palm trunks used to consolidate the underground galleries. The average length of the galleries is 2.5 km, and include vertical wells every 20 to 30 meters for ventilation and maintenance.
Foggaras allow passive transport of water depends entirely on the force of gravity. As groundwater is captured and flows underground, prevents evaporation, reaching the vicinity of the oasis, where it flows into a ditch open pit. A small triangular pool (quasri) collects the water that reaches the oasis through the ditch and with the help of a comb (kesria) water is distributed throughout the oasis. Foggaras originated in Iran, where they are known as ghanat or quanat, have existed for more than three thousand years. Foggaras are also used in Morocco, where they are called rhettaras.
In Algeria, the job of keeping foggaras who is ungrateful and dangerous, has gradually been abandoned. In its current state, many of the galleries that have collapsed foggaras allow only a small amount of water. Moreover, the development of modern agriculture, which requires pumping large quantities of water at high pressure, the water table has dropped, causing the drying of foggaras.
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The gentle slope of the galleries slows the flow of water, avoiding friction with the ground and erosion. To make the system work foggaras, oases to be found in depressions or valleys, or at the foot of a hill, that is, below the water table. The oasis of Adrar are located below the plateau Tadmit where ground water emerges. This ingenious method gravity to transport water throughout the year.
The materials used for the construction of the surrounding foggaras come: Blocks of stone are cut by a conglomerate of clay and straw, and palm trunks used to consolidate the underground galleries. The average length of the galleries is 2.5 km, and include vertical wells every 20 to 30 meters for ventilation and maintenance.
Foggaras allow passive transport of water depends entirely on the force of gravity. As groundwater is captured and flows underground, prevents evaporation, reaching the vicinity of the oasis, where it flows into a ditch open pit. A small triangular pool (quasri) collects the water that reaches the oasis through the ditch and with the help of a comb (kesria) water is distributed throughout the oasis. Foggaras originated in Iran, where they are known as ghanat or quanat, have existed for more than three thousand years. Foggaras are also used in Morocco, where they are called rhettaras.
In Algeria, the job of keeping foggaras who is ungrateful and dangerous, has gradually been abandoned. In its current state, many of the galleries that have collapsed foggaras allow only a small amount of water. Moreover, the development of modern agriculture, which requires pumping large quantities of water at high pressure, the water table has dropped, causing the drying of foggaras.
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