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The mean annual rainfall of South Africa is only about 450 mm. The unpredictability of the rainfall as well as extremely high potential evaporation result in the country being water stressed. It is predicted that the demand for water will outstrip the supply within three decades. In order to mitigate this problem, various huge transcatchment schemes have been constructed in South Africa and some of its neighboring countries, but these schemes will only postpone the drying up of the main rivers within a few years. For this reason, the importance of groundwater as a resource is increasing. South Africa does not have significant groundwater resources, although the dolomitic aquifers in the West and Far West Rand have a huge groundwater potential. These dolomites contain (under natural conditions) at least twice the volume of water of the Vaal Dam, which is the main water resource for the economic heartland of South Africa. Alkaline and mafic-alkaline dikes of Pilanesburg age divide the dolomites into several...

In the 1960s, the Malmani dolomite landscape of the Transvaal Sequence on the Far West Rand experienced ground subsidence in the form of sudden catastrophic sinkhole formations and extensive development of dolines by gradual subsidence. The management of the gold mines had decided to dewater some of the dolomitic compartments to allow their workers to extract the gold-bearing ore of the underlying Witwatersrand Supergroup economically and safely. Several of the gold mines on the Far West Rand have now reached the end of their life span and are due to be decommissioned. Dewatering will be discontinued. Some of the dykes that form the boundaries of the individual dolomitic compartments have been breached by mining activities so that flooding of one compartment will eventually impact on the other compartments. The eventual static level of the water-table in this new ‘super-compartment’, as well as the points of decant of the dolomitic water, are uncertain. Flooding of the ‘super-compartment’ will cause the original dolomitic eyes feeding the Wonderfontein Spruit to start flowing again, which will impact on groundwater quality and ground instability. Of particular concern is the occurrence of millions of tonnes of mine tailings within the catchment area. The most important problem in the catchment area is that the sedimentary phase of the Wonderfontein Spruit and its impoundments is continually being enriched with heavy metals and radio nuclides originating at the mining works. These could be remobilized and released into the downstream water, causing deterioration of water quality for downstream users. Copyright © 2006 John Wiley & Sons, Ltd.

Water lies at the heart of many of Africa's problems. Although Africa as a whole is only slightly below the world average in terms of the available water resources per capita, and better off than Europe or Asia, it is beset by three critical groups of problem, one largely natural, the second very definitely manmade, the third somewhere in-between. The first centres on the distribution and reliability of resources. The second is related to the distribution and growth in human population. The third is the intimate link between water and disease in Africa, and the widespread lack of access to safe drinking water amongst the poorer communities. Much of the water that is theoretically available is either naturally dangerous for human health or else polluted by human activities lack of sewage treatment or pollution from agriculture, mining and industry. Despite the WHO's International Drinking Water Supply and Sanitation Decade in the 1980s, and the WHO's continuing Water, Sanitation and Health activities, the numbers without access to safe water continue to grow (WHO, 2004 website). Over 300 million still lack access to safe water in sub-Saharan Africa. Lack of access to safe water is worst in rural areas, where women and children often spend considerable time fetching water: over 1 .2 billion people worldwide live more than 1 5 min walk from a safe water source, many in Africa (Rodda, 1994). In the Southern African Development Community, 56% of rural communities lack access to safe water, against only 22% in urban areas. High temperatures favour the proliferation of many microbes as well as vectors of disease like the Anopheles mosquito. It is estimated that if malaria had been properly tackled 30 years ago when effective control measures first became available, Africa's GDP would now be about $100 billion greater (World Health Organisation, 2001). Public health is, therefore, not solely a question of safe water provision, but also of sound management of the water environment in order to control all water-related disease. Together, these factors make the average per capita water resource statistic largely meaningless in practical terms. Africa's climatic location is a fundamental source of its problems. Straggling the equator and extending beyond both tropics, the climates of Africa are dominated by the Hadley Cells. These circulation cells create both the excessive rains on the rising limb along the Intertropical Convergence Zone around the equator and the desiccation of the adiabatically heated air on the sinking limb around the subtropics, which suppresses convective activity and rain formation. This results in a grossly uneven distribution of water resources, ranging from desert to equatorial rainforest. Fluctuations in the strength of the Hadley Cells, their associated monsoons and other elements of atmospheric circulation in the tropics, like the Biennial Oscillation and the Southern Oscillation, also result in considerable and often critical unreliability of rainfall throughout much of the continent. To this is now being added clearly discernable climatic change, some perhaps natural, some apparently related to human-induced global warming. The frequency of drought appears to have increased in recent decades, particularly in the Sahel and the Horn of Africa. Drought in tropical Africa is often associated with the reversals of ocean currents in the equatorial Pacific known as El Nino, which have been getting more intense in recent years. At the same time, there have been some unusually intense tropical cyclones emanating from the western side of the Indian Ocean in the southern hemisphere. The hurricane seasons in 1999-2001 were especially problematic: the worst event for 50 years occurred between January and March 2000, when Cyclones Eline, Gloria and Hudah saw 150,000 ha flooded in Mozambique, hundreds killed and over 1 .25 million made homeless in southern Africa, including Botswana, South Africa, Zambia, Zimbabwe and Madagascar. There are, however, some more purely human elements in the increasing frequencies of droughts and flood disasters. Overgrazing, deforestation and devegetation have created long-term changes in the water balance of many desert margins, increasing the proportion of rainfall draining away as storm runoff, thereby increasing flood problems, eroding the top soil, reducing soil moisture retention and decreasing the recharge of aquifers. The eminent climatologist, Reid Bryson, has even suggested that increased dust from agricultural activity in semiarid regions has increased the atmospheric albedo or reflectivity, cooling the upper air and so inducing air subsidence which suppresses potentially rain-creating convective cells even further (Bryson and Murray, 1977). The net result has been that the West African monsoon has penetrated less far northwards into the Sahel in recent decades, aggravating the incidence of drought and famine. Similarly, the devastating Nile floods of 1988 were created by a combination of the 1000-year rainfall event and more rapid runoff caused by deforestation in the headwaters. Floods like these also carry risks for public health, increasing the incidence of diarrhoea, dysentery, cholera

Commercial afforestation in South Africa dates back to the 1870s and started as an alternative to the fast disappearing indigenous timber resource. It involves the planting of exotic timber species and has impacts on water resources, soil biodiversity, landscapes, etc. Commercial afforestation of land has been subjected to regulation through the Afforestation Permit System (APS) since 1972, primarily to protect the national water resource. Since the APS no longer adequately dealt with afforestation regulation, it was replaced in 1999 with a procedure that was supposed to integrate the requirements of relevant legislation and general environmental management principles. This paper is a theoretical review of the background and development of the new South African Streamflow Reduction Activities licensing procedure, as well as whether it complies with the requirements of an environmental management system such as ISO 14001. The main conclusion is that the new procedure, although an improvement on the previous procedure, still has shortcomings especially with regard to the operational and decommissioning phases of forestry in South Africa. It is recommended that these aspects be addressed in order to mitigate the impact of forestry on water sustainability in South Africa.

Because South Africa is situated in a semi-dry region, the limited water resources are placed under increasing pressure by consumers from different sectors. Irrigation consumes more than half of the available water resources in South Africa. In the Northwest Province large volumes of water are found in dolomitic aquifers. Since 1970 irrigation from these aquifers has resulted in an exponential growth in the withdrawal of groundwater. The purpose of this study is to evaluate the effectiveness of groundwater utilization with centre-pivot irrigation in the Northwest Province, as well as to identify the most important variables that influence this effectiveness. Factor Analysis and Multiple Regression Analysis were used to establish a model with which the probable effectiveness of groundwater utilization on a specific farm can be predicted. The results show that four variables have a significant effect on the net profit margin from centre-pivot irrigation in the study area, namely: • Knowledge regarding the water capacity of the soil • Adjusting irrigation according to precipitation • The use of a yield target for fertiliser application, and • Soil characteristics The above parameters were used to develop a model with which farmers in the study area can be ranked according to the effectiveness of their water usage for centre-pivot irrigation.

van der Walt, I.J., Jones, J.A.A., Woo, M.K. (2006). Introduction - Water sustainability. Physical Geography, 27: 283-285.