Slightly Less Dammed

Nov. 8, 2016
Ec Jk Blog

We’ve covered the pros and cons of dam removal projects in the past, but less so the consequences of building dams; one exception is this account of a writer’s trip to China during the construction of the Three Gorges project.

The main reason, of course, for building large dams has been to generate hydroelectric power, which is often hailed as a clean and renewable source of energy, despite the environmental damage such projects can cause. Brazil, which relies on hydropower for most of its electricity, is trying a new approach. In the past it built large dams on the Amazon River that—much as the Three Gorges and other large hydroelectric projects have done—flooded large areas and displaced tremendous numbers of people. To avoid the widespread destruction of such projects, Brazil is now turning to run-of-river dams, a series of smaller dams that flood much less area. This approach has been widely used in Canada and elsewhere.

Rather than creating huge reservoirs, run-of-river projects use the river’s natural flow to turn turbines. Dozens of these smaller dams are planned for the Amazon over the next few decades. The problem, the government is finding, is that run-of-river projects are less effective than traditional massive dams, and the energy they produce fluctuates seasonally as river flows increase or decease during rainy and dry seasons. A prolonged drought could spell disaster for energy production.

In light of these problems, and because of fears that climate change might cause increasing periods of drought, some Brazilian officials are advocating a return to traditional large-reservoir dams, even with their attendant environmental and social consequences. Others believe alternate sources of energy like solar and wind will gradually replace hydroelectric power. Still others favor the use of natural gas, which, as this article from The Economist notes, is produced as a by-product of pumping oil from offshore wells and is therefore relatively cheap.

Have you dealt with the consequences of dam building or dam removal projects? What do you think of the trade-offs of the run-of-river approach?

About the Author

Janice Kaspersen

Janice Kaspersen is the former editor of Erosion Control and Stormwater magazines.