GEO-6 Regional Assessment for Africa


• warming of the tropical Atlantic Ocean, intensifying Atlantic monsoons and increasing precipitation and total water storage over West and Central Africa;


• warming of the central Indian Ocean, decreasing precipitation and total water storage over East Africa;


• a high frequency of flooding events, increasing total water storage in the Zambezi and Okavango Basins;


•


extraction of fossil groundwater, decreasing total water storage in Saharan aquifers;


• deforestation, decreasing total water storage in the three sub-basins of the Congo River Basin, namely Ubangi, Congo and Sangha;


• the construction of dams, increasing total water storage in the Blue Nile and Atbara sub-basins.


Figure 2.3.6: Total water stored in the land annually in Africa, 2003–2012


In addition, mountainous and forested areas that replenish many of the continent’s river flows, or ‘water towers’, are under extreme pressure due to deforestation and encroachment (McClain et al. 2013). The water towers of Kenya, for example, are key national assets to the country’s economy (UNEP 2012), however many areas of the Mau Forest Complex, the largest of the water towers, have been converted to agriculture and pasture land.


According to MacDonald et al. (2012), groundwater is a major source of Africa’s drinking water, while its use for irrigation is projected to increase substantially to combat growing food insecurity. Some quantitative continent-wide


Figure 2.3.7: Annual precipitation over Africa, 2003–2012


Note: Colour-coded linear images generated over Africa for the period 01/2003–09/2012 (GRACE data) Source: Ahmed et al. 2014


64


Note: Colour-coded linear images generated over Africa for the period 01/2003–09/2012 (Tropical Rainfall Measuring Mission (TRMM) Source: Ahmed et al. 2014

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