Southern Africa Drought #4

Widespread rain and flooding and frequent severe storm warnings can lead to the conclusion that the Southern Africa drought is rapidly coming to an end. This is however not necessarily the case especially in the winter rainfall areas of the country. The following table  indicating current dam levels as a % of full capacity illustrates this:

 Capacity       30.1.17     30.1.16
            Dam    million m3           %          %
Sterkfontein        2 617            87            87
Vaal        2 604            63            53
Bloemhof        1 240            35            22
Vanderkloof        3 171            53            66
Gariep        5 196            52            49
Free State total       15 971            57            55
Theewaterskloof           479            34            51
W Cape total        1 853            38            46
Pongolapoort        2 267            38            48
kZN total        4 669            47            54
E Cape total        1 826            58            74
Limpopo total        1 508            64            62
Katse / Mohale (Lesotho)        2 376            45            47
Mpumalanga total        2 520            66            62
Total RSA and Lesotho       31 913            55            56

The overall 1% point reduction in levels indicates how little the recent rains have improved the situation on a year on year basis. Free State dams, representing half the region’s capacity, improved by 2% points, pointing to a grim position in much of the rest of the region. Of greatest concern is the Western Cape whose topography and rainfall patterns do not lend themselves to major dams. Its largest dam, Theewaterskloof, has suffered a one third drop in reserves in the last 12 months and a further drop of this amount in the coming months would leave it dangerously close to the “Absolute Minimum Level”. The Eastern Cape and kZN are also struggling despite the impression given by daily weather forecasts that they should be receiving good rains. [Source: Dept of Water Affairs]

Adding to the concern that the drought may not be at an end, The International Research Institute for Climate and Society at Columbia University’s Earth Institute predicts that the current tropical Pacific sea surface temperature anomaly of close to -0.5°C, which is the threshold for a weak La Niña, is likely to trend back fairly quickly to a zero number such that by the middle of the year the probability of an El Niño phenomenon outweighs that of a La Niña, although a close to neutral position is assigned the highest probability for most of the year. For the next six months the likelihood is for higher than normal temperatures over most of the region and indeed over most of Africa though this is said to be less likely over the SW Cape Province.

The rainfall in our location in Gauteng Province has been particularly good but noticeably patchy.

2016/17 2015/16
mm mm
July 23 8
Aug 0 1
Sept 13 32
Oct 73 30
Nov 213 89
Dec 169 105
Jan 186 218
 Total 677 483

Looking back over the years, the last time I recorded higher July to January totals was in 2009/10 and before that 1998/99. The late ’90s were particularly wet with the only years over the last 40 to have higher than 1916’s 213 mm in November being 1995, 1997 and 1998. 64% of November 2016’s rain was over the 9th to 11th.


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