Dams have been used for centuries to ensure adequate flow of fresh water. However, during the twentieth century, large dams were built at an accelerating rate. By some estimates more than 47,000 dams were built throughout the world. Dams were not only water resources for food production and energy generation they were also perceived as symbols of modernity. The initial enthusiasm about dams was lost with the rise of concerns regarding their environmental and social impacts. Therefore, dam construction to mitigate water scarcity, exacerbated by climate change particularly in arid and semi-arid regions, became a controversial decision. It is imperative that dams impact assessments are conducted and the results are incorporated into decisions regarding building new dams and managing the established ones. We reviewed the available research on socio-ecological impacts of dams particularly in developing countries and also conducted an AHP-SWOT analysis of a dam in a dry region. Our goal was to conduct a sustainability assessment of dams impacts and to offer insights for their construction and management.
Our tentative findings indicate that based on the pillars of sustainability theory the impacts of dams can be classified to environmental, social, economic and institutional. Dams have both positive and negative consequences. On the positive side time-stable fresh water supplies, power generation and flood control, have resulted in numerous social and economic benefits including stabilized national food prices, and supply of clean energy. However, the negative consequences include a range of issues some of which are location specific and others are more general which can be observed across different projects. The negative environmental impacts consist of erosion of resilience, loss of grazing area and fish habitat. Socio-economic impacts include increased vulnerability of downstream population, increased inequality due to changes in water access, reduced food security, migration, changes in rural economy and employment structure, and changes in non-material or cultural aspects of life. The AHP-SWOT analyses indicate that experts perceive that negative factors (weakness and threats) of the studied dam are relatively more important than positive factors (strengths and opportunities). Among the negative factors, threats, have the highest weight due to uncertainty caused by climate change. We conclude that, despite significant benefits, dams have serious negative environmental, social and economic consequences. Such impacts can make sustainable management of dams a challenge and building of new ones unjustifiable.