ABSTRACT
Increased storage capacity due to dams, reservoirs and irrigation channels as would be associated with the ILR, by definition results in decreased flow velocity. This, in turn, leads to accumulation of suspended loads, which favor eutrophication, reduced oxygen concentrations and sedimentation. These conditions typically force a shift in ecological community structure towards organisms that are tolerant of poor water quality with reduced oxygen content: ideal conditions for important vectors of water-borne disease including both snails and biting flies. While the benefits of hydropower, irrigation, improved access to clean water, and improved transportation infrastructure are surely arguments in favor of large dams, these benefits must be weighed against future costs, some of which are more difficult to assess. The environmental consequences of dams
often have indirect effects on human health. Salinization and waterlogging of soils due to over-irrigation, sedimentation and erosion, alteration of seasonal flow patterns (affecting downstream users and ecology), damage to fisheries, deforestation, and increased use of and exposure to pesticides with an increase in arable land area can all lead to adverse impacts on human health.
