Zimbabwe: Landuse in Dry Tropical Savannas

Water resources

Zimbabwe is basically a semi-arid country. As rain falls in one season from November to April, most rivers, especially in the drier parts of the country, are not perennial. Only the major rivers such as Munyati, Manyame, Mazowe, Save and Runde are perennial. However, in dry years even these large rivers dry up in the months of August to November. Because mean annual rainfall is generally low in Zimbabwe and the rivers are not perennial, it is necessary for water received during the main rainy season to be stored for use during the dry season. An extensive network of dams has been constructed throughout the country. These range from small dams on commercial farms and in rural areas, to large dams for the purpose of supplying water to major cities and for irrigation.

Studies carried out by the Department of Water Development found that the mean annual run-off for the whole of Zimbabwe is 19910 million m3, with current shortage at 5831 million m3, indicating that there is scope for storing more water. Current utilisation is only 22% of mean annual run-off. However, if all this water were to be stored, the flow of international rivers such as Zambezi would be affected. Thus, there is a need to balance the amount of inter-country dam storage with the need to maintain certain minimum flow level in the international rivers.

Besides surface water storage, Zimbabwe also relies on underground water. Numerous boreholes and wells have been drilled throughout the country. Small, shallow, low yielding wells and boreholes in communal areas supply villages with drinking water, especially during the dry season and dry years. Deeper, high yielding wells are used for irrigation on commercial farms.

The quality of both surface and groundwater supplies in Zimbabwe is generally good at present, since there is little overall use of chemicals in Zimbabwean agriculture. Localised pollution does, however exist. The eutrophication of Lake Chivero south of Harare is a case in point. In addition, the storage capacity of the major reservoir is threatened by siltation resulting from heavy soil losses in most of the catchment areas. However, the challenge to government and the development process is to ensure the provision of clean drinking water to the whole population.

Water resources related links:

• AFDB.org: Water Resources Management, Supply, Sanitation (PDF)
• FAO Aquastat: Zimbabwe Country Profile