River conservation in central and tropical
N. Pacini and D.M. Harper
Despite a century and a half of European colonization of the continent, the ecology of the rivers of tropical Africa is still relatively unknown. The major rivers, and the lure of their sources, were the focal point for early exploration and, as a result, the knowledge that exists is unevenly distributed. A large amount of information and understanding exists for the Nile, for example (Rzóska, 1976) when compared with the Congo. Human uses of rivers though, are as old as our species and will continue to affect rivers as long as humankind inhabits the earth. Early Egyptian civilizations, 5000 years BC, first regulated the Nile, creating basins for flood waters and irrigation canals to build their cities. In the middle of the 20th century, the building of the High Dam at Aswan definitively changed the ecology of the entire region. The future, however, may produce even greater surprises following the launching in 1997 of the Tuzhka Project which, within some 25 years, could build an artificial channel across western Egypt to replicate the ancient river (Tadesse, 1998).
The colonization of Africa brought with it the expertise of European-style civil service, and the application of new scientific ideas (Worthington, 1958), but the development of ecological knowledge was still uneven. It was focused upon the development of fisheries (and more oriented towards lakes than rivers), upon the ecology and control of disease vectors, the control of exotic species, and the supply of drinking water. The development of concepts of conservation on land, with the growth of National Parks and other protected areas, was not mirrored by any form of aquatic conservation except where floodplains contained large mammal herds. Since the middle of the 20th century, much money and effort has been spent understanding the ecological impact of large reservoirs on major river systems such as Kariba on the Zambezi, Volta in Ghana, and Aswan on the Nile, but almost all were conducted after the event, and had little or no influence on management decisions. Even up to the present day, the occurrence of serious environmental evaluation of water resource development schemes is rare and conservation is very much a ‘catching-up’ activity, usually after the expatriate engineers, technologists and economists have gone home (Pacini et al., 1999). Capital aid programmes are rarely linked to assistance for subsequent running costs and, as a result, many large projects – from unserviced University equipment to unfunded resettlement schemes – have failed to deliver environmental improvements (see also Wishart et al., this volume, Part II).
The conservation of tropical aquatic habitats has been overshadowed by the mobilization of public interest and support generated by the urgent need to conserve tropical rain forests. Running waters in particular still have a low profile within the new nations of tropical Africa. National parks and protected areas are often delimited by rivers instead of being set around them, thus disregarding the link between rivers and their catchments. This link is particularly crucial in Africa where water is more precious than in many other parts of the world. Indeed, current estimates forecast significant decreases in water