ABSTRACT
The relationship between land use and water is of interest worldwide. In many developing countries changes in land use are rapidly taking place and the largest change in terms of land area, and arguably also in terms of water resource impacts, arises from afforestation and deforestation activities. Whilst demands for agricultural land and firewood place increasing pressure on the dwindling indigenous forest resource, demands for timber and pulp are leading to increasing areas undergoing commercial afforestation with fast-growing monocultures of often exotic tree species. Agricultural demands for irrigation water compete with those of urban conurbations and industry for water supply. Hydroelectricity, often erroneously thought to have a neutral effect on water resources because evaporation from reservoirs is not taken into account, is another big user of water in many developing countries, particularly those in southern Africa. For example, the flow over the Victoria Falls is approximately equal to the flow from the Kariba dam downstream; all the additional flow into Lake Kariba from the northern-flowing rivers from Zimbabwe and the southern-flowing rivers from Zambia can be considered as lost to evaporation. Expanding industry, increasing urban populations without adequate sewage treatment facilities and greater intensification of agriculture, whilst not significantly affecting the quantity of the resource, all pose problems for its quality.
