Environmental impacts of hydroelectrics.

Projects powerful dams can cause irreversible environmental changes, in a very large geographical areas, hence, have the potential to cause significant impacts. Has the criticism of these projects over the past decade. The harshest critics argue that the social, environmental and economic impacts of these dams outweigh their benefits and, therefore, not justified the construction of large dams. Others mention that in some cases, the environmental and social costs can be avoided or reduced to an acceptable level, if evaluated carefully, the potential problems and corrective measures are implemented.
The area of ​​influence of a dam extends from the upper limits of the reservoir to the estuaries and coastal areas and offshore, and include the reservoir, the dam and the basin of the river downstream of the dam. There are direct environmental impacts associated with the construction of the dam, but the most important impacts are the result of the impoundment of water, flooding the land to form the reservoir, and the alteration of water flow below. These effects exert direct impacts on soils, vegetation, wildlife and wild lands, fisheries, climate and population of the area.
The indirect effects of the dam include those associated with the construction, maintenance and operation of the dam and the development of agricultural, industrial or municipal enable the dam.
In addition to the direct and indirect effects of dam construction on the environment, it must consider the effects of the environment on the dam. The main environmental factors affecting the performance and life of the dam are those that relate to the use of land, water and other resources in the catchment areas upstream of the reservoir that can cause greater accumulation of silt , and changes in the amount and quality of the reservoir water and river.

References

•   Dixon, J.A., L.M. Talbot, y G J M Le Moigne. 1989. Dams and the Environment Considerations in 3 World Bank Proijects. Documento T6cnico del Banco Mundial 110. Washington D.C.: Banco Mundial.
• Banco Mundial. 1989. "Environmental Policy for Dam and Reservoir Projects." Directriz Operativo 4.00, Anexo B. Banco Mundial, Washington D.C.
• http://es.wikibooks.org/wiki/Impactos_ambientales/Proyectos_hidroel%C3%A9ctricos.