To Dam or Not to Dam?by Nathan Bonnisseau
The Beam, September 3, 2018
The gigantism of these structures, and the sheer number of dams on rivers,
created problems that can become too large to handle.
Rivers and humans have a long standing history. A simple look at the human population growth over time makes it easy to see how water streams and access to clean water influence the repartition.
The oldest record of water stream alteration is located a few kilometers upstream from Amman, the capital of modern day Jordan. This also happens to be where the first premises of an agricultural civilization happened, between the two great rivers of the Tigris and the Euphrates. Before that of course, beavers had secured the technology to build their own houses and ecosystems. Fun fact: the only animal construction visible from space is a beaver dam in Canada.
Is it really a coincidence that the first recordings of artificial alteration of river streams happened where agriculture and writing were -- we believe -- developed? Probably not. Control of water flow is a life or death question for human settlements. As the most basic need of life, water drives development, not the contrary.
Water is both a blessing and a curse. A source of life when it is clean and flowing regularly, rivers can turn into a deadly disease vector when contaminated, and destroy entire areas when they transform into furious rapids in the case of flooding.
Why do we build dams?
Most dams were built during the 20th century, at a time where streams were seen as little more than power sources and garbage disposal. Dams are pretty much as old as civilization because they serve three purposes absolutely pivotal in the development and maintaining of human settlements: food, communications, and energy.
Smart usage of water and diverting of water to artificial courses was also in use in mountainous regions where agriculture demanded heavy infrastructure work such as the Chinese rice fields or the Inca aqueducts and irrigation systems. Whether it is for agricultural irrigation, or to replace animal or manpower, dams have proved a worthy ally to progress and modernity.
What is the impact of building a dam?
On the other hand, modern dams have the capacity to flood entire regions for the needs of population centers downstream. The gigantism of these structures, and the sheer number of dams on rivers, created problems that can become too large to handle.
The first visible effect was the -- somewhat logical -- disappearance of anadromous species like salmon and trout, that are born and grow in rivers, but live their adult lives in oceans. Encumbered by massive human dams, their road to reproduction and life cycle was cut off, leading salmon to disappear sometimes altogether from a region.
In regions such as the Nile delta or the Mississippi river banks, another problem quickly became a central issue. Weakened rivers could not bring the necessary alluvium and sediment downstream to counteract the relentless erosion of wind and salt water. This caused accelerated sinking of the coastal lands, and a rapid progression of the sea front.
In worst case scenarios, large dams can result in catastrophic floods. The Banqiao dam disaster of 1975 remains as the deadliest dam failure in human history killing 171,000 people and displacing 2 million more. For three days, a particularly stationary typhoon called Nina caused record breaking precipitations in the Henan region in China. This once-in-2000-years flood caused the Banqiao dam, a 500 million m3 reservoir dam to break and trigger a chain reaction downriver. The People's Republic Army Air Force was forced to destroy several other dams by airstrike to prevent further uncontrolled floodings.
Does it make sense to still build more dams?
Dams have undoubtedly helped tame the environment humans live in, prevented famines and mitigated natural disasters. Today, most dams are built for the purpose of electricity generation. In 2015 hydropower generated 16.6% of the world's total electricity and 70% of all renewable electricity. This figure is expected to increase about 3.1% each year for the next 25 years, with renewable energies jumping from 20% to more than 50% of the output worldwide.
There are 48,000 dams in operation in the world, and more are being built each year. Dams have considerable advantages against other energy production sources: they are reliable, modulable, and consume no water nor emit carbon dioxide. It takes, however, millions of tons of concrete to build dams, the roads leading to it and the grid connection of these superstructures. The Hoover dam, a mid-sized dam built in the '30s in the US, took the equivalent of two highways between New York and Los Angeles (that's 12,000 km back and forth) to build.
In the context of risk aversion in a world of unpredictable catastrophic weather event, multiplied by the development of cheap local and decentralized power, do we still need superstructures to provide our societies with electricity?
The sustainable transition is a pervasive movement that is not limited to measuring CO2 emissions or providing a given amount of clean energy. It is above all a redefinition of the relationship between humans and nature. A relationship that tries to avoid altering natural settings and limit the impact of human-made structures on the livelihoods of ecosystems.
The proliferation of dams worldwide represents a period of carelessness in the history of humanity. The balance of nature cannot be disrupted on this scale without provoking unwelcome side effects, such as the functional extinction of the Yangtze river dolphins, or the disappearance of salmons for a century from English rivers (they're back in some parts though).
Plan A and RiverWatch are leading a campaign against the installation of dams on the Balkan river system. By organizing lawsuits and local action, we delay the start of these potentially illegal constructions, and protect this region famed for its natural beauty and remoteness.
These large-scale development projects alter regions for a few hundred years into the future. Some even say that dams will be the last buildings standing when humans go extinct. Until, like everything, they eventually break from the relentless push of water and gravity. Dams are not a fatality, nor is this technology a problem in itself, but we should think of how to slowly move away from them, before we are moved by them.
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