WATER!

Rainfall is the main source of water, and is critical to the success of agriculture and industry and to the survival of people, wildlife and plants.

Most of southern Africa’s rainfall starts out as evaporation from the Indian Ocean. While rain is the source of virtually all water in the region, much ofit is never used. The high temperatures result in about two-thirds of the water evaporating back into the air, although this varies from place to place. Evaporation is a significant water loss—more water is evaporated from Lake Kariba in one year than is consumed in Zimbabwe in the same period. Another fifth is used up by natural vegetation and crops. The remaining 15 percent, which runs off into lakes and rivers, or sinks into the ground, is the portion available for use by people and animals.

THE LIFE-GIVING RAINS.

In southern Africa rain usually falls during a five- to seven – month period between October and May and decreases in amount from northeast to southwest. Amounts range from an average of 3,000 millimeters (mm) of rain in some areas to as low as 10 mm in the driest part of Namibia’s Desert on the west coast. Rainfall is difficult to predict from year to year, but climate scientists have shown there is a cycle of nine wet years followed by nine dry years in most parts of the region.

Water is a valuable resource in southern Africa, vital to households, industries, livestock and agriculture as well as the environment. Rainfall can be unreliable and some areas chronically receive low amounts while others have excess. Many proposals for dams and water transfers have been put forward to make water supply more dependable. Some areas also practice water conservation. As demand for water grows, southern Africa is developing agreements for sharing water and resolving competition for it.

Rain is more erratic in the drier areas on the region’s western side, and these areas undergo great swings in rainfall amount. A few areas experience a different rainfall pattern, with most of Tanzania having two shorter rainy seasons close together followed by a longer dry season, and south Africa’s extreme southern tip receiving winter rainfall.

The region’s southwest- most of Namibia and Botswana, the western half of South Africa, Angola’s southwest tip and parts of southern Zimbabwe—is all a low – rainfall, dry area. It is difficult to grow all but the most drought-resistant crops without using some artificial watering at least 500 mm of rain is needed during the growing season to grow crops). The erratic nature of the rains can also mean that enough falls to support crops. But it may be at the wrong time.

WATER SUPPLY

Some countries have responded to the problem of low, erratic or seasonal rainfall by building dams to store water. The water can then be pumped to houses or industrial centres, or used for irrigation of crops or watering of livestock. These dams may also be used to control damaging floods. Zimbabwe, Botswana, Namibia and South Africa rely heavily on large and small dams for all these purposes.

REGIONAL COOPERATION

The southern African Development Community (SADC) has initiated discussions among its members to pre-empty possible conflicts over sharing of Zambezi river water, or any other shares water bodies in the region.

Started in 1985 as the Zambezi river Action Plan, or ZACPlan, discussion on ways to share water equitably among the Zambezi river states has grown into a draft treaty among all SADC members governing any shared watercourse in the SADC region.

The treaty was ratified by SADC in August 1994.

The treaty will be an important step for SADC. With several countries eyeing the Zambezi waters thirstily and other water-rich countries considering international trade in water, the potential exists for mutually beneficial cooperation.

Water is a scarce and precious commodity in many parts of southern Africa. As demand increases it will have to be managed more and more carefully to ensure enough for all, including the environment.