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The rainfall climate of South Africa is one of great variability. Seasonal rainfall percentage deviations since 1960 demonstrate wide fluctuations about the long-term average and it is in this context that large rainfall deficits must be assessed. Between July of 1960 and June of 2004, there have been 8 summer-rainfall seasons where rainfall for the entire summer-rainfall area has been less than 80% of normal. A deficit of 25% is normally regarded as a severe meteorological drought but it can be safely assumed that a shortfall of 20% from normal rainfall will cause crop and water shortfalls in many regions accompanied by social and economic hardship.
All but the south-western and southern regions of South Africa rely on summer rainfall, which normally falls between October and March, the summer season. Rainfall is heaviest in the east and decreases westward. For convenience the rainfall season is taken to run from July until June of the following year, but rainfall outside of the summer season is usually insignificant.
The consequence of rainfall being confined to six months of the year is that most crops can only be grown during this period. Similarly, the recharging of water resources is also confined to these crucial six months. When the seasonal rainfall is seriously below normal, crop yields are poor and ground and dam water levels fall dangerously low. Should these conditions occur in swift succession, as in the periods from 1964 to 1970, 1991 to 1995 and again from 2002 to 2005, there is insufficient time for natural resources and the economy to recover from each rainfall-deficit period.
Graph showing percentage-of-normal rainfall for Gauteng – bad rainfall years have a medium term effect
Simultaneous to low rainfall are cloud-free skies and high temperatures. The effect of abnormally high temperatures is an increase in evapotranspiration as well as stress on plants whilst further depleting surface-water reserves through evaporation.
The most serious impact, other than dwindling water supplies, is the effect on staple crops and, ultimately, commercial crops. In 1992/1993, undoubtedly one of the most widespread droughts of the last 45 years, maize had to be imported to South Africa (as well as the rest of southern Africa). The knock-on effect of crop failure could be seen in the population drift from rural areas into the cities, farm labour lay-offs and farm closures as well as an increasing indebtedness in the agricultural sector.
Graph showing percentage-of-normal rainfall for Freestate – maize crop impact
Other serious impacts brought about by drought are the devastating veld fires which destroy large areas of grazing at a time when grass is in short supply. Commercial timber and orchards are also prone to damage at such times. In 1992 there were several huge fires which destroyed thousands of hectares of grassland. In one of the worst events, during August, at least nine people perished. In 1994, a combination of unusually strong winds and very dry conditions saw large areas of grazing and timber destroyed. Six people died in one such fire in July of that year. Again, in July of 2002, Mpumalanga was devastated by fires that destroyed 24,000 ha of pasture and left four people dead and damages amounting to more than R32 million.
Severity of Recent Droughts
It is very difficult to look at the entire summer-rainfall region and deduce that drought affected all of these areas equally. On the contrary, some of the provinces in South Africa appear to suffer more harshly than others at times of rainfall deficit.