Use of decision support systems to improve dam planning and dam ...

to pay sufficient attention to environmental impacts and those, invariably poor people adversely affected by
their construction and operation. Those who have had to be resettled and those whose livelihoods have been
affected by changes in river flow regimes have tended to pay the price of dam construction (Box 1.1).
In Africa, relatively few large dams have been built and, after Asia, the continent has the lowest per capita
storage of any continent (Figure 1.1). Although the need for economic development is urgent, many people
continue to rely on natural resources and agriculture to sustain their livelihoods. Consequently, assessing all
the implications of dams, both positive and negative, is of paramount importance both when planning new
dams and when revising the design or operating rules of existing ones.
Currently the World Bank, the African Development Bank, the New Partnership for African Development
(NEPAD) and other influential institutions are advocating increased development of hydraulic infrastructure
on the African continent. The current position of the World Bank is that major water resource projects
provide the basis for broad regional development, with “significant direct and indirect benefits for poor
people” (World Bank 2004). As a result, many dams are being planned and it is likely that many will be built
in the near future. There is no comprehensive list but Appendix 2 provides details of some of the new dams
currently being built or planned in Africa.
2
Box 1.1. How dams can have adverse impacts on people
Although dams have brought benefits to many millions of people, their construction has not been without
cost for many others. Globally, it is estimated that between 40 and 80 million people have been displaced
as a consequence of the construction of large dams (WCD 2000a). Many of these people have not been
adequately compensated. People living downstream may also be adversely affected as a consequence
of changes in flow regimes caused by the way large dams are operated. In many developing countries,
changes in flow, brought about by large dams, have resulted in the degradation of natural resources upon
which many people rely.
For example, in some places dams, by reducing flooding, have significantly diminished the productivity
of floodplain and estuarine fisheries as well as adversely impacting recession agriculture (Acreman et al.
2000). Dams may also cause negative public health impacts, for example, through the creation of breeding
habitats for disease vectors, such as snails for schistosomiasis and Anopheles mosquitoes for malaria (Jobin
1999). People living upstream of dams may be 100% affected through loss of land to the reservoir. More
people downstream may be slightly to severely affected by degradation of the river system.
An example of where a dam may have affected the livelihoods of people living downstream,
Kafue Flats, Zambia. (Picture source, www.asla.org)