The Change of Water Supply

Commencing with this particular blog post, I will start to delve further into the thematic and connect 'climate change' with 'water use in Africa'. This entry will be focussing on water supply on the African continent under the influence of the climate change and the changing conditions that it comes along with. The question that could reasonably come up here is why start with water supply? I want to reply to that by illustrating the most crucial importance of water supply as a brief introduction.

Firstly, people in Africa rely on natural water sources like local rivers which obviously are fed by rainfall or melting glaciers, for example the Mount Kilimanjaro. Any decrease of these sources would exacerbate the already very tense situation on the African continent. 

Secondly, climate change poses an immerse threat and risk for the poverty eradication in Africa, which would be even more compounded once a decrease of natural water sources takes place.

For a better comprehension of the diverse situation in Africa, and according to de Wit and Stankiewicz (2006), there are three regimes the continent can be divided into:

Dry regime: The most prevalent type of regimes in Africa covering 41% of the continent. These are areas with no perennial surface water drainage receiving less than 400mm precipitation per year. 

Intermediate regime: Surface water supply is directly affected by a change in climate, which is why this regime can also be described as 'unstable'. Areas receiving between 400 – 1000mm per year. This type covers approximately 25% of the continent.

Wet regime: Hereby, the drainage density decreases slightly when rainfaill is increasing due to factors like vegetation. Areas receiving over 1000 mm per year.

To emphasise the importance of understanding the regimes and to give a propect on the situation in Africa over the next decades, two figures of the paper of de Wit and Stankiewicz (2006) prove to be very useful.

Figure A and C: 'Annual rainfall in a region' and 'Predicted change'. De Wit and Stankiewicz (2006), p. 1919.

Figure A shows the implications of a 10% drop in rainfall on perennial drainage density. The black line curve hereby shows the predicted change in perennial drainage. The red section represents the dry regime, yellow the intermediate regime and green the wet regime, divided by the amount of precipitation. For example, if a region would receive a precipitation drop of 10% from 550mm per year (intermediate regime) to 495mm per year, it would be considered as being part of the dry regime. The most crucial issue hereby would be the impact on the drainage: the same would drop by 25%! 

As to be seen in Figure C, the worst affected and thus most endangered areas would be southern and northern Africa with a predicted rainfall drop of 10% and more. Such a drop would lead to a reduced drainage of 17% by 2050 (de Wit and Stankiewicz (2006)). East Africa is to be considered as mostly intermediate, due to the immense influence of the Nile. 

All things considered, the influence of climate change on the water supply in Africa has been elucidated abundantly clear. The danger that the upcoming changes entail require comprehensive examination. The next blog post will discuss the possibilities of transboundary water resources and basin management regarding their upcoming challenges and potential approach to help regions facing increasing water scarcity.

References

De Wit, M., Stankiewicz, J. (2006) "Changes in Surface Water Supply Across Africa with Predicted Climate Change", Science 311, pp. 1917-1920.