In my lecture today I was particularly interested in the section regarding the continued use of non-renewable fossil based aquifers as a water source. In areas where water is in such high demand, this precious resource is often used unsustainably and at the cost of future generations. Typically, it is needed to satisfy the need for water in everyday life and for large-scale irrigation and farming projects which contribute to the country’s economic development. ‘Fossil water’ is water that has stayed sealed underground due to changes in the geology of the area. In the past, when the climatic forces were different, the sandstone acted as a sponge and soaked up the torrential rains that fell during ancient storms. Built up over thousands or millions of years, the ‘fossil water’ is now depleting at a rapid rate as a result of extraction. Some even believe it will follow a similar path to fossil fuels, especially in some of the world’s driest regions - it will become just as valuable leading to over-exploitation.
The main focus of this post will be the Nubian Sandstone Aquifer System (NSAS) - one of the largest fossil aquifer systems in the world. The Aquifer is found under Libya, Egypt, Sudan and Chad and its extent is believed to be over 2,000,000 km2. It contains around 540,000 km2 of freshwater, 15,340 km2 of which is classified as exploitable. To give an idea of the vast scale of the volume of this fossil water, Sass says in his paper (2011) that the NSAS, ‘holds more freshwater than all the freshwater surface lakes and rivers on earth combined.’ Nonetheless, because water stored in the NSAS is not being replenished, the aquifer is regarded as non-renewable and therefore extraction will undeniably lead to the complete depletion of the source.
As shown in Figure 2, the NSAS has two major sections; the Nubian Aquifer System is spread across the four states while the other reservoir, called the Post-Nubian Aquifer System, is found under just Egypt and Libya.
So, how much water is being extracted from the NSAS? In Egypt and Libya, well over 40 billion m3 of water has been extracted to date. Evidence that extraction is having an impact can be seen in the fact that, “all but 3%,” of free flowing wells have been replaced with deeper wells as a result of a 60m drawdown that has occurred in the immediate areas surrounding the wells. Forecasts for the extent of drawdown suggest that drawdowns around wells and pumping centres will continue and will eventually ‘coalesce into a NSAS-wide drawdown.’ Voss (2013) argues that the estimated transboundary impacts from drawdown are relatively minimal in the near future, claiming that drawdown will only cross into neighbouring countries around 2060. For example, the East Oweinat development in Egypt will only have a 10m drawdown by 2060. While this is a relatively small depletion suggesting a rather positive outlook for the future of water availability from the NSAS, the development will have in fact crossed into Sudan by this point. This has the potential to create a range of hydropolitical issues as well as the danger of oases and shallow wells disappearing as drawdown continues.
The main focus of this post will be the Nubian Sandstone Aquifer System (NSAS) - one of the largest fossil aquifer systems in the world. The Aquifer is found under Libya, Egypt, Sudan and Chad and its extent is believed to be over 2,000,000 km2. It contains around 540,000 km2 of freshwater, 15,340 km2 of which is classified as exploitable. To give an idea of the vast scale of the volume of this fossil water, Sass says in his paper (2011) that the NSAS, ‘holds more freshwater than all the freshwater surface lakes and rivers on earth combined.’ Nonetheless, because water stored in the NSAS is not being replenished, the aquifer is regarded as non-renewable and therefore extraction will undeniably lead to the complete depletion of the source.
Figure 2: Hydro-geological map of the Nubian Sandstone Aquifer Systems
So, how much water is being extracted from the NSAS? In Egypt and Libya, well over 40 billion m3 of water has been extracted to date. Evidence that extraction is having an impact can be seen in the fact that, “all but 3%,” of free flowing wells have been replaced with deeper wells as a result of a 60m drawdown that has occurred in the immediate areas surrounding the wells. Forecasts for the extent of drawdown suggest that drawdowns around wells and pumping centres will continue and will eventually ‘coalesce into a NSAS-wide drawdown.’ Voss (2013) argues that the estimated transboundary impacts from drawdown are relatively minimal in the near future, claiming that drawdown will only cross into neighbouring countries around 2060. For example, the East Oweinat development in Egypt will only have a 10m drawdown by 2060. While this is a relatively small depletion suggesting a rather positive outlook for the future of water availability from the NSAS, the development will have in fact crossed into Sudan by this point. This has the potential to create a range of hydropolitical issues as well as the danger of oases and shallow wells disappearing as drawdown continues.
References
- Hutton, R.E. and Utton, A.E., 1989. Transboundary Groundwaters: The Bellagio Draft Treaty. Natural Resources Forum, Vol. 29, 663–722.
- Voss, C.I. and Soliman, S.M., 2013. The transboundary, non-renewable Nubian Aquifer System of Chad, Egypt, Libya and Sudan. Hydrogeology Journal Vol. 22, 441-468
- Voss, C.I. and Soliman, S.M., 2013. The transboundary, non-renewable Nubian Aquifer System of Chad, Egypt, Libya and Sudan. Hydrogeology Journal Vol. 22, 441-468
- National Geographic (2008) "Underground "fossil Water" running out" (WWW) [http://news.nationalgeographic.com/news/2010/05/100505-fossil-water-radioactive-science-environment/]
-Sass, E (2011) What lies beneath libyas Great man made river - [http://mentalfloss.com/article/27260/what-lies-beneath-libyas-great-manmade-river]
-Sass, E (2011) What lies beneath libyas Great man made river - [http://mentalfloss.com/article/27260/what-lies-beneath-libyas-great-manmade-river]
No comments:
Post a Comment