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close this bookCERES No. 074 (FAO Ceres, 1980, 50 p.)
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View the documentTanzania to weigh impact on environment

Tanzania to weigh impact on environment

- blueprint for better planning?

Tanzania plans a vast hydroelectric complex on the Rufiji River intended, among other things, to prevent the devastating floods that take place every five years leading to great economic losses.

But Africa's dismal experience in clumsy interferences with the environment by dam builders has caused the Tanzanian planners to exercise great caution. They have commissioned a thorough environment impact study covering a huge area surrounding the proposed dam site. Its findings, which have just been published, and the actual construction following its recommendations may prove an important blueprint for ecologically sound future development planning.

Hydroelectric constructions can cause socioeconomic upheavals for the local populations, affect animal, plant and fish life adversely and reduce soil fertility. The Rufiji scheme may well be the first major project to take into account from the outset all these problems in the light of present experience.

The Rufiji is Tanzania's largest river, its basin covering about one fifth of the country with perhaps 10 percent of the national population living there. Some 100000 Tanzanians could benefit from the dam, to be built at Stiegler's Gorge, 230 km from the river mouth. Construction will begin in 1982. The project could help ensure the country's self-sufficiency in electric power generation in the long term.

Given proper planning, the development complex would also create a good foundation for agricultural production independent of the river's flood seasons. It would provide year-round water transport in the basin, a boon for increased agricultural trade and for the transport of mangrove timber.

"Hydroelectric dams are becoming essential development projects in the face of dwindling fossil fuels," comments a specialist of the United Nations Environment Programme, which carried out the study for the Rufiji River Basin Development Authority. "But when man superimposes water over extensive terrestrial systems, he not only disturbs existing orders and natural ecological balances, but also creates new and unfamiliar systems and biological associations over which he has little or no control and for which, so far, he has practically no effective or feasible management experience. The rational attitude, therefore, is to anticipate possible problems and to be prepared to face them as best as possible."

To begin with, the new dam is likely to affect the animal population of Tanzania's biggest game reserve, Selous, which lies in the region. A rich variety of game - 90 000 elephants, 20 000 hippos as well as lion, rhino, leopard, zebra, impala and crocodile - will have to be protected from people who will find easy access to the area as it becomes more developed.

Declining soil fertility may result from the greatly reduced flow of silt to the flood plain. Salinization of the land must be prevented. There is also the danger of aquatic weeds spreading as a result of the increased supply of organic nutrient matter in the reservoir from the catchment area.

The Rufiji dam will disturb the river's ecosystem. Many species of fish, whose life cycles include essential periods of migration, will be prevented from travelling downstream. The mangrove forests, which abound in the river valley and provide local timber supplies, may also be seriously affected by the drying of the delta. It could also disturb the thriving local prawn industry.

Finally, there is the socioeconomic effect of large-scale dam building in developing regions, covered at great length by another report prepared for the World Conference on Agrarian Reform and Rural Development, held recently in Rome. An FAO specialist says that "the idea of new agricultural communities on virgin or reclaimed land, often a by-product of huge new dam projects, has always had tremendous appeal with governments, in part because new lands offer an alternative to thorny problems of agrarian reform in settled areas." But actual experience seldom justifies initial expectations.

Among the practical problems described by the report were the undue expectations of quick success by the settlers, the absence of ethnic homogeneity among them, lack of social amenities and non-agricultural work opportunities in the new communities, excessively rigid direction by governmental bureaucracies, inadequate training and extension services in the project areas, and official disregard for the special needs of women-particularly for the generation of an independent income.

Another difficulty unsuspected by the planners has been the hostility generated among people outside the new settlements by the special treatment given to the settlers. The present consensus among planners is that the more successful a settlement may appear, the more resentment it is likely to attract.

The environment impact study for the Tanzanian project, carried out by the international experts in cooperation with local specialists, is to form the basis of a multipurpose scheme that will be prepared by the Rufiji River Development Authority. Given the conflicts between the long-term needs of the environment and the short-term needs of large populations for increased supplies of food and fuel, the Tanzanian compromise between the two may well attract the urgent attention of industrial development planners everywhere.