Polski
Large hydroelectric dams have played a key role in the global economy and environment over the years, providing energy, drinking water, helping to irrigate fields and protecting valleys from flooding. They also supported the development of the local economy. The world‘s best-known dams, such as the Three Gorges Dam in China and the Hoover Dam in the United States, continue to impress with their scale and technical sophistication, but in recent years we have seen a change in trends in the context of the construction of such reservoirs, which may suggest the coming of the end of their era.
Problems associated with major hydroelectric dams
Large hydroelectric dams, while considered beneficial in many respects, also bring with them a number of problems. By partitioning valleys, artificial water reservoirs are created, which undoubtedly have a negative impact on the environment. The social costs of building such facilities are also significant. Displacement of local communities, such as the displacement of 90% of the population as a result of the construction of Garrison Dam on the Missouri River, the impact on their culture and heritage are common consequences of such projects.
Finally, economic costs, including the high cost of dam construction and maintenance, are also significant. Often these projects are accompanied by the risk of budget overruns, affecting their profitability and social and environmental consequences. An example is China, where the decline in interest in dam construction is linked to rising costs and changes in energy policy.
Alternatives to large dams
As the search for “replacements” for large dams continues, it is becoming increasingly popular to invest in renewable energy sources such as solar, wind and geothermal power. Water efficiency technologies are also an important aspect. These include smart irrigation systems and other conservation technologies and the use of closed-loop circuits. The alternatives help develop more sustainable and environmentally friendly energy sources and efficient water resource management.
Cases of abandonment of large dams and demolition of existing dams
Brazil – policy change in construction of mega-dams in the Amazon
In 2018. The Brazilian government has announced an end to its policy of building mega-dams in the Amazon. The decision came in response to hardline resistance from environmentalists and indigenous groups. Concerns focused on the environmental impact of reservoir construction and the rising social, environmental and financial costs.
Chile – HidroAysén project
In 2014. The Chilean government has canceled a plan to build five dams on Patagonia’s rivers. The reason for the cancellation was concerns about the environmental impact of the investment, destruction of ecosystems and changes in river flow. The project encountered strong resistance from the public and the international environmental community, which contributed to the government’s final decision.
Myanmar – Myitsone Dam project
In 2011. President Thein Sein announced the suspension of construction of the Myitsone Dam. The reasons also included concerns about environmental impact, displacement of people and destruction of ecosystems. The project was met with strong public opposition in the country, which influenced the authorities’ decision.
Little by little, demolition of existing structures is becoming more common. The world’s largest completed dismantling project was two hydroelectric dams (64-meter-high Glines Canyon Dam and 32-meter-high Elwha Dam) on the Elwha River in the US, which were dismantled between 2011 and 2013. Another significant project in the US – the dismantling of 4 dams on the Klamath River – is likely to begin soon.
The common reasons for abandoning the construction of large dams or dismantling existing ones in the cases mentioned are precisely concerns about environmental impact, destruction of ecosystems, changes in river flows and population displacement. Undoubtedly important, therefore, is the growing public awareness of the consequences of building huge reservoirs. On the other hand, however, it can no longer be said to be a widespread trend. In Europe, a total of 342 dams were dismantled between 1996 and 2019, of which about 95% were actually very low barriers, and in the US, only 2.3% of the dams dismantled were 7.5 to 15 meters high, and only 2.0% were higher than 15 meters.
The largest hydroelectric dams – what does the future hold?
So has the era of large dams come to an end? In recent years, we have seen a reduction in the number of new dam projects, which may suggest a change in the approach to energy and water management. Rising construction and maintenance costs, negative environmental impacts, growing public resistance, and the development of alternative energy sources such as solar and wind power are influencing these trends. Cases of large dams being abandoned or even demolished are mainly due to concerns about environmental impact, ecosystem destruction and population displacement.
In the long term, energy transition and climate change, will undoubtedly have an impact on reducing the development and importance of large dams. The growing popularity of wind and solar power, encouraging regulations in this area and their lower environmental impact are making these technologies more common.
