Dam failure has a whole spectrum of consequences and creates new types of hazards: environmental, ecological, economical, financial, social, socio-economic, political, cultural heritage, resettlement of indigenous people etc.
Dam breakage generally leads to considerable human losses because the area below a dam is usually densely populated. The table below mentions some of the dam-related emergencies with largest human losses:
The environmental impact of dam breakage can be significant: flood water can cover large areas, destroying natural conditions for plants and fauna, but this is a short-term impact. Operational rules should be provided for regulating downstream flows at critical times to protect habitat.
Environmental hazards due to the erection of the dam in a river basin are even more serious as the natural water cycle can be affected. During the design of the project, mitigation measures need to be considered:
- vegetation should be cleared from the area to be flooded;
- outlet structures should optimize downstream water temperature and quality to preserve natural conditions;
- measures providing for the migration of fish and other aquatic organisms should be implemented.
Such accidents also cause substantial socio-economic losses such as loss of property, loss of production, losses due to the non-availability of the reservoir, unemployment, slow-down in economic development, etc.
Other consequences can also emerge, such as water shortage for irrigation and domestic purposes, political unrest.. Cultural heritage monuments can also be damaged as a result of strong flood waves.
Finally, the creation of a reservoir may also induce earthquakes due to the additional stress of water on the earth’s crust or the increase of pore pressure in the rocks; this effect (reservoir–induced seismicity or RIS) can be described as the triggering of a natural event by human interference.