Nubian sandstone aquifer
The Nubian Sandstone Aquifer (English Nubian Sandstone Aquifer ) is an extensive sedimentary rock body in the subsurface of the Nubian Desert , which houses a large reservoir with fossil groundwater .
With a volume of approx. 373,000 km³ (this corresponds to approx. 10% of the volume of the Mediterranean ; estimates of the storage volume vary considerably), it is one of the world's most important aquifers .
With a vertical extent of 140 to 230 meters and a depth of 800 to 4500 meters, it extends over an area of approx. 150,000 square kilometers over parts of the states of Egypt , Libya , Sudan and Chad . The age of the groundwater in the sandstone is several hundred to more than 1 million years.
In some places, the aquiferous layers reach the surface and form the lakes of Ounianga and the small lakes in the Fada Archei wildlife reserve in the northeastern Chad Basin .
Emergence
Newer theories assume that the fossil water resources of Northeast Africa originated in a pluvial period, whereby the soils stored the seeped water.
Use, risks
Due to the prevailing hyperarid climate, almost no new groundwater formation takes place in this aquifer system; its water level sank by about 60 meters due to massive use in recent years; With continued use in today's style, optimistic forecasts assume that the aquifer will be exhausted in approx. 200 years.
The oases of the Western Desert in Egypt Bahariya , Farafra , Abu Minkar , Dahkla and Kharga are all located in depressions from which artesian springs gushed until around 50 years ago . The population pressure and the intensification of agriculture resulted in an overexploitation of the springs, so that they finally dried up. The Egyptian Ministry of Irrigation began to mine fossil groundwater in the oases in 1981.
In the 1970s, several large irrigation projects were started in the area of the Kufra oases in Libya , which became known primarily for the artificially irrigated fields in a circular shape (see also the film Home by Yann Arthus-Bertrand ). The Libyan regime boasted about to a man-made river to have built for irrigation and drinking water supply, thus the project is also Great man-made river project ( Great Man-Made River, GMMRP or GMMR ).
The non-renewable fossil water resources are also exploited for the supply and disposal of uranium mining by the AREVA group in Niger .
Web links
- W. Aeschbach-Hertig: Physical basics of the climate archives ice and groundwater: 7. Dating of groundwater ( Memento from February 1, 2016 in the Internet Archive ). Script from the Institute for Environmental Physics, Heidelberg University (PDF; 3.5 MB).
literature
- Ahmed M. Sefelnasr: Development of groundwater flow model for water resources management in the development areas of the western desert, Egypt. Dissertation , Martin Luther University Halle-Wittenberg , 2007.
source
- Kristina Bergmann: Problematic land reclamation in Egypt. In: NZZ , April 7, 2010.
Individual evidence
- ^ Martin Gehlen: Irrigation: Sahara water for Libya's coast. In: Zeit Online. December 27, 2010, accessed April 23, 2011 .
- ↑ a b Henrike Berkefeld: The desert swims ( memento from July 19, 2012 in the web archive archive.today ). Badische Zeitung , April 23, 2011.
- ↑ Artificial oases thanks to primeval water. Badische Zeitung, April 23, 2011 ( Memento from July 19, 2012 in the web archive archive.today ).
- ↑ Kristina Bergmann: Problematic new land reclamation in Egypt. In: NZZ , April 7, 2010.
- ↑ Bettina Rühl: The "clean" solution. From Niger and German nuclear power plants. Das Feature series , Deutschlandfunk , October 26, 2010 (broadcast manuscript as PDF).