Irrational Use?

Over-abstraction and irrigation

What is clear is that some over-abstraction has already begun to take place. The depletion and dissection of interconnected sub-basins can leave large intermediate underground areas and oases dry. The drying out of waters and lands can increase desertification processes which in turn can lead to ecosystem and habitat destruction, negatively impacting both humans and other species that depend on them for survival.

In Libya’s Kufra sub-basin, for example, the pumping of water for the Great Man-Made River Project has led to reduced water levels and the drying up of desert lakes linked to oases. In Egypt’s Kharga Oasis, water levels in the north section dropped by a maximum of 60 m from 1960 to 1998, with water abstractions taken originally from shallow wells and springs and now taken 97% from deep wells.

As another example, in Chad, groundwater levels in some NSAS areas have declined considerably, forcing many people to move. Losses of artesian levels, humid zones and oases that depend on seepage and springs from the NSAS have been observed. Sites of high global environmental significance including desert lakes are now threatened by dune intrusion and pollution.

Agriculture poses many significant threats. Over-abstracting groundwater for irrigation purposes (e.g. for intensive wheat production) can lead to the mobilization of salts and the ‘salinization’ of land and soil, thereby making it less valuable for further production. Such land degradation can again lead to ecosystem and biodiversity destruction. Another problem is that agricultural pollution from the poor use of nutrient fertilizers and pesticides applied to crops can leach into the water table and impact groundwater quality, as can pollution from human waste and sewage systems.