Introduction
A dam is a structure specifically constructed to obstruct the flow of moving water, and by extension raising the water level. Dams are built for various purposes, such as a means of flood control, water storage, and a source of hydroelectric power, specifically hydroelectric ones. Some dams are also used in transportation and inland navigation by acting as bridges that connect one side of a body of water to the next. In other words, dams can have many benefits for a developing society. Because of their perceived benefits, many dams have been built all over the world—at least 50,000 dams of at least 15 meters have been built around the world’s rivers. This number would be bigger if dams of a smaller size are taken into account (Bosshard).
However, even though dams seem advantageous in a general sense, the negative effects of dams should also be looked upon. There are many drawbacks that are associated in building dams, and they affect the environment negatively. For short period of time, constructing mega-dams may look a huge benefit to our life, but this causes lots of environmental issues for now and finally this will bring a bad impact on our future generation. In fact, there are many examples to prove that dams do more harm than good. As a result, dams should not be relied upon as a decent generator of electricity—dams cannot be considered as a ‘green’ source of hydroelectric power.
Environmental Impacts of Dams
In order to better understand the negative impacts of dams, it is first important how dams affect the environment. Knowing the impacts of dams in the environment is highly crucial—the effects of dams in the environment may not be readily apparent but they are guaranteed to negatively affect the environment in a long term. Furthermore, these effects prove to be irreversible and thus more severe as time passes (McCully, “River No More: The Environmental Effects of Large Dams”).
Effects on Aquatic Ecosystem. First, dams can disrupt the lives of aquatic organisms. Dams block natural fish migrations, which is a bad thing if the spawning and rearing area of the fishes differ, such as in the case of salmon. As Klein puts it, “Salmon can have a trouble to go to an ocean by concrete dams that defy even the most acrobatic cohorts” (441). They also change the state of aquatic life in a manner that is not conducible for the native species living there, such as encouraging the growth of invasive species such as algae and the like. One alarming effect of dams can be exemplified in the Yangtze River, the natural habitat of the Chinese River dolphin. There are only less than a hundred of these species known to existence, and their endangered status is further aggravated by the dams in the area (Heggelund).
Dams also have a negative effect on the aquatic ecosystem in general as well. It disrupts the water flow in the area by changing the ecosystem to a free-flowing water system to a static one. As a result, the sediments that are supposed to shift from one place to another end up getting stuck in the riverbed, causing changes in the oxygen levels which is bad news for aquatic life. Maek et al found out that the sediments trapped in dams do not only reduce oxygen state of the water, they also create methane emission hot spots which contribute negatively to the global warming condition.
Dams and Deforestation. Dams are also the cause of deforestation. In order for hydroelectric dams to be properly built, large areas of land, usually reserved for trees, need to be deforested and flooded, leading to a huge loss of trees and eventual release of greenhouse gases. In addition, people who settled in that areas need to relocate, possibly furthering the effects of deforestation elsewhere. Naomi Klein recounts a situation in which she witnessed a mining company cut down the trees in an area to build hydroelectric plants.:
“”In the skouries forest near Ierissos where our van was stopped, the catalyst was a plan by the Canadian mining company Eldorado Gold to clear cut a large swath of old-growth forest and reengineer the local water system in order to build a massive open-pit gold and copper mine, along with processing plant, and a large underground mine.”
When trees are cut down, the terrestrial organisms suffer as a result. Animals that once lived on these forests which are now cut down are forced to relocate elsewhere, and this disrupts the terrestrial ecosystem in general. If the primary sources of food in the terrestrial ecosystem—trees—are disturbed, the whole food chain suffers as a result. In other words, it can be said that dams do not only impact the aquatic ecosystem negatively, but also the terrestrial ecosystem as well.
Since dams cause trees to be cut down, it can be said that they are one of the causes of air pollution as well. As mentioned earlier, the sediments that are accumulated in dams produce methane gases, which in turn, could contribute to global warming to a possibly greater extent than greenhouse gases (Wockner).
Aside from this, the mining industry near these dams can be a source of air pollution as well by producing noxious fumes that are toxic to the environment. Naomi Kleins explains that one common tactic mining companies use is that they participate in carbon offset programs just to have an excuse for polluting the environment. Furthermore, these carbon programs force people to be displaced from their natural habitats as well (222).
The same goes for hydroelectric dams—many studies highlight the positive effect of hydroelectric dams but more often than not they fail to take into account the effects of it on global warming, not to mention the steep prices associated with it (Guegan, Madani, & Uvo).
Dams: Capitalism vs Environmentalism
All too often, dams are built for capitalist purposes. Since there are many environmental impacts of dams are shown above, the feasibility of building dams for business purposes has been extensively questioned. The effects of dams on society will be discussed below.
Roles of Dams in Developing Countries. Since developing countries rely on businesses to generate revenue which would help the economy, many businesses are built there and dams are no exception. For example, companies which utilize dams such as mining and aluminum companies are built beside dams in order to supposedly help the people by giving them jobs and to improve the economy in general. However, these have negative effects which far outnumber their advantages. For example, the supposedly cheap cost of aluminum mining does not compensate its negative effects on the environment and the lifestyles of people (Switkes).
First, dams are constructed in order to conserve water for future use. While this is a good point, the problem lies in the cost in constructing the dams itself (Imhof & Lanza). In order to construct dams, land that could have been used for agriculture will be used and many people will have to be relocated (Watkins).
Secondly, dams are used to generate hydroelectric energy by utilizing the water in order to power turbines. As with the above, the large costs associated in building dams can prove to be a major case against this factor. Costs required to run and maintain hydroelectric plants are three times larger compared to the ones needed to run thermal plants (McCully, “Expensive and Dirty Hydro”).
Dams Damaging People’s Lives. Dams can also affect people’s lives negatively. In Naomi Klein’s This Changes Everything, there are two examples of this case: the Chinese peasants and the Elwha Kallam tribe:
“Chinese peasants who rely on traditional subsistence activities like agriculture and fishing have a history of militant uprisings against industrial projects that cause displacement and disease, whether toxic factories, high-way, or mega-dams” (351).
“The lower Elwha Kallam tribe in Washington State made similar points when its leaders fought to remove two dams on the Elwha River. They argued successfully that by interfering with salmon runs the dam violated their treaty rights to fish” (375).
Conclusion
Some geoengineers and economists claims that constructing mega-dam will be a nice solution for most of our economic problems. As Naomi Klein proposed, the bad impacts from capitalism in modern society may not have visually appeared until now. However, in the long term of period, we will have several environmental issues. For example, dams can impact aquatic and terrestrial ecosystems, as well as contribute to air pollution. It also does not bode well on an economic level, as the costs for building and maintaining dams may not compensate for its effects.
Maybe it is time for people to reconsider building dams. As Naomi Klein puts it, "We deny because we fear that letting in the full reality of this crisis will change everything" (4).
Works Cited
Bosshard, Peter. “10 Things You Should Know About Dams” International Rivers. International Rivers, 27 May 2014. Web. 16 June 2016.
Guegan, Marion, Madani, Kaveh, & Uvo, Cynthia. “Climate Change Effects on the High-Elevation Hydropower System with Consideration of Warming Impacts on Electricity Demand and Pricing”. Hydropower Reform Coalition. Hydropower Reform Coalition, July 2012. Web. 16 June 2016.
Heggelund, Gorild. “The Three Gorges Dam: Taming the Waters of the Yangtze Creating Social Instability?” Mount Holyoke College. Mount Holyoke College, February 2003. Web. 16 June 2016.
Imhof, Aviva & Lanza, Guy. ““Greenwashing Hydropower: The Problems with Big Dams” ”. International Rivers. International Rivers, 15 January 2010. Web. 16 June 2016.
Klein, Naomi. This Changes Everything: Capitalism vs the Climate. New York: Simon and Schuster, 2014. Print.
Maeck, Andreas, DelSontro, Tonya, McGinnis, Daniel, et al. “Sediment Trapping by Dams Creates Methane Emission Hot Spots”. Environmental Science and Technology 47.15 (2013):8130 – 8137. Web. 16 June 2016.
McCully, Patrick. “River No More: The Environmental Effects of Large Dams”. International Rivers. International Rivers, January 2001. Web. 16 June 2016.
McCully, Patrick. “Expensive and Dirty Hydro”. International Rivers. International Rivers, February 2000. Web. 16 June 2016.
Switkes, Glenn. “Foiling the Aluminum Industry” International Rivers. International Rivers, August 2005. Web. 16 June 2016.
Watkins, Thayer. “The San-men (Three Gate) Gorge Dam on the Yellow River”. San Jose State University Economics Department. San Jose State University, January 2014. Web. 16 June 2016.
Wockner, Gary. “Dams Cause Climate Change, They are Not Clean Energy”. EcoWatch. EcoWatch, 14 August 2014. Web. 16 June 2016.
