Environmental Impact Assessment of Dams at Construction and Operation Phases

Environmental impact assessment (EIA) in the projects of civil engineering, was not being considered by many countries until recent years. However, in recent decades of 20th century and after observing environmental impacts of some of the projects, it was stated that the environmental factors played a noticeable role in speeding and directing of projects. Dam construction as one of the important civil and developing projects have positive and negative effects on environment. The environmental impacts can be categorized based on different criteria e.g. short and long term, impacts on surface and the ecosystem of the region, upstream and downstream side of dam, and social and economic impacts. Whereas dams have positive effects, it is necessary to minimize the negative impacts of dams toward stable development. At the same time, it is known that the consequences and impacts are different during construction and operation period in terms of intensity, importance and extent. In this paper, at first, the effectible geophysical factors related to river and reservoir water, vegetation and animal, social, economic and cultural factors are studied. Then, as a case study, Gotvand dam for quantifying the environmental impacts using the Iranian matrix are presented.