Water crisis and global warming in Southern Africa

The socio-economic future of communities in Southern Africa depends on agriculture, fisheries, mining, industry, manufacturing, tourism and industrial development to generate employment and growth. This can only be achieved if water of acceptable quality and quantity can be availed and supplied in time at the right locations and at low cost to support the planned, expected socio-economic development in the region. The effects global warming has made the water issue a crisis in Southern Africa thus threatening the region's food security and socio-economic developmental initiatives.

Much of SADC is arid or semi arid and rainfall is variable, often unreliable. The region experiences regular wet and dry spells, that is, several years of abundant rain followed by periods of scarcity. Droughts have also occurred in the region throughout recorded history, and global warming is among the major causes. Thus the increasing severities of these droughts are directly related to human activities and in some cases have some natural explanation.

Water availability is variably both spatially and temporally. Groundwater is important throughout southern Africa during the dry season and year round in the arid zones. Seasonal variations and unreliability of precipitation make irrigation much more important in the region than might otherwise be the case. Irrigation is often regarded as a way of increasing agricultural productivity without increasing the amount of land under production.

Irrigation accounts for almost three-quarters of all water used in the region. Of this 40-60% of the water drawn from rivers and dams is lost before it reaches the land under irrigation, mainly through sippage and evaporation. This not only throws away a valuable resource, but causes serious environmental problems such as soil salinisation and waterlogging. Such conditions are undesirable for crops and other plants, and ultimately remove land from production.

Southern Africa has an estimated 9.1 million hectares of land where productivity could be improved through irrigation. About 1.8 million hectares are already under irrigation. While irrigation is desirable in some cases, it is often used to grow crops with low economic value. In South Africa and Zimbabwe less than 80% of the irrigated crops are low value. This is an uneconomic use of water, requiring some form of agricultural subsidy.

Also river basins, lakes and coastal areas in southern Africa a subjected to various mining operations, because of the existence of products such as coal, iron, gypsum, salt, soda, coral sand and gravel. Examples are the extraction of gold by Russian mining companies in Zimbabwe, soda ash in Makgadikgadi in Botswana, gypsum and iron ore in Kafue Flats in Zambia, salt in Etosha Namibia, coral sand along the coast of Tanzania and Mozambique and coal along the Zambezi valley.

One of the main effects of mining is the contamination of water by soluble substances and toxic liquid effluents. Diamond production around Chiadzwa in Marange, Zimbabwe has polluted the Save River, while in Dundo in the north-east of Angola has polluted the Kasai River flowing into the Democratic Republic Of Congo. In Zimbabwe diamond and gold by Chinese and Russian governments is extracted by opening up the river beds. Mineral processing in the SADC region contributes more than one million tonnes of sulphates to the environment, annually. In South Africa, for example, regular tests at more than 40 sampling points in the Vaal catchment area show that mine dumps on the East Rand leach into the Rietspuit stream, among other toxic chemicals, 'alarming levels of sulphates' that exceed European standards for surface water.

As demands for potable water continue to increase world-wide so have human impacts on freshwater systems. Water used for domestic purposes, industry or agriculture is frequently returned to its original source polluted or contaminated with chemicals or other harmful substances, reducing the amount of good quality water.

Population growth, increasing urbanization and industrialization all contribute to the increase in waste and water pollution in Southern Africa. The main sources of pollution are found in urban areas and major developments such as mines, and irrigated and other rain-fed commercial agricultural estates. Water contaminated with poisons from agricultural estates, mines and industries runs through some areas where it may be used for drinking and washing or watering livestock and gardens. Chorela and other water borne diseases are often found in water contaminated with untreated human waste and sewage.

Excessive use of nitrogen-base fertilizers pollute the soil, resulting in acidification which releases toxic substances, impairing the growth of crops. About 5000 sq km of land in South Africa are acidified--10% of the countries cultivated land.

Manufacturing and service industries are the primary source of pollution in Southern Africa, producing tonnes of effluents, solid waste and air pollutants. Major polluters include thermal electric power stations which burn coal or petroleum products, fertilizer factories, textile mills, chemical manufacturing plants, pulp and paper plants, slaughter houses and tanneries.

Of the world's 0.62% volume contained as fresh water about half of this volume is below a depth of 800m and practically not easily available for any use on the surface. Ground water is important through Southern Africa during the dry season and year round in arid zones.

Extensive droughts have afflicted Southern Africa in recent times, particularly during the following seasons: 1946-47, 1965-66, 1982-83, and 1986-87. The 1991-92, 1994-95 and 2000-2008. The 21st century years have been described as the most severe years in Zimbabwe embalmed with the melting economic situation prevailing in the country to date which was caused by Mugabe's agrarian program. These years were also major El Nino years. El Nino has an effect on weather over a quarter of the world's surface. It develops as the warm waters of the tropical Pacific, spread eastwards in concert with shifting patterns of atmospheric pressure. These natural warming events alter weather patterns world-wide, causing droughts in Southern Africa and contributing to their severity.

Southern Africa is party to about 70 regional and international environmental treaties and conventions, some of which have shaped the region's policy thinking. International conventions on the environment are anew phenomenon in Southern Africa, as they are throughout the African continent. Participation is clearly tempered with national interests of individual countries, but regional conventions embody a new resolve to work together.