Dams are major driver of global environmental change

May 17, 2017
The Roman dam at Cornalvo in Spain has been in use for almost two millennia. Credit: Wikipedia/ CC BY-SA 2.0

Water reservoirs created by damming rivers could have significant impacts on the world's carbon cycle and climate system that aren't being accounted for, a new study concludes.

The study, conducted by researchers at the University of Waterloo and the Université libre de Bruxelles, appears in Nature Communications. It found that man-made dam reservoirs trap nearly one-fifth of the organic moving from land to ocean via the world's rivers.

While they can act as a significant source or sink for carbon dioxide, reservoirs are poorly represented in current climate change models.

"Dams don't just have local environmental impacts. It's clear they play a key role in the global and therefore the Earth's climate," said Philippe Van Cappellen, a Canada Excellence Research Chair in Ecohydrology at Waterloo and the study's co-author. "For more accurate climate predictions, we need to better understand the impact of reservoirs."

There are currently in excess of 70,000 large dams worldwide. With the continuing construction of new dams, more than 90 per cent of the world's rivers will be fragmented by at least one dam within the next 15 years.

The study's researchers used a novel method to determine what happens to organic carbon traveling down rivers and were able to capture the impact of more than 70 per cent of the world's man-made reservoirs by volume. Their model links known physical parameters such as water flow and reservoir size with processes that determine the fate of in impounded rivers.

"With the model used in this study, we can better quantify and predict how dams affect carbon exchanges on a global scale," said Van Cappellen, a professor in Waterloo's Department of Earth and Environmental Sciences.

In similar recent studies, the group of researchers also found that ongoing dam construction impedes the transport of nutrients such as phosphorus, nitrogen and silicon through river networks. The changes in nutrient flow have global impacts on the quality of water delivered to wetlands, lakes, floodplains and coastal marine areas downstream.

"We're essentially increasing the number of artificial lakes every time we build a dam," said Taylor Maavara, lead author and a PhD student at Waterloo. "This changes the flow of water and the materials it carries, including nutrients and carbon."

Explore further: Study finds rivers and streams release more greenhouse gas than all lakes

Related Stories

Better dam planning strategies

January 7, 2015

When dams are built they have an impact not only on the flow of water in the river, but also on the people who live downstream and on the surrounding ecosystems. By placing data from close to 6,500 existing large dams on ...

Recommended for you

Supervolcanoes: A key to America's electric future?

August 16, 2017

Most of the lithium used to make the lithium-ion batteries that power modern electronics comes from Australia and Chile. But Stanford scientists say there are large deposits in sources right here in America: supervolcanoes.

Climate change will cut crop yields: study

August 15, 2017

Climate change will have a negative effect on key crops such as wheat, rice, and maize, according to a major scientific report out Tuesday that reviewed 70 prior studies on global warming and agriculture.

How friction evolves during an earthquake

August 15, 2017

By simulating earthquakes in a lab, engineers at Caltech have documented the evolution of friction during an earthquake—measuring what could once only be inferred, and shedding light on one of the biggest unknowns in earthquake ...

4 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

Joker23
2 / 5 (8) May 17, 2017
Listening to and reading articles like this tell me the Author(s) consider the Human Race to be the cause of everything bad that happens in the world. We're bad because we want dams to generate electricity, and coal to Generate electricity. The animals we eat use up resources and generate greenhouse gas. After listening to each article one's eyes glaze over and the credibility of the articles are perceived as over reaction by people with an agenda and it destroys credibility. What is the solution? Wind energy.........? what happens when we FINALLY discover that, aside from killing millions of birds, the wind generators are disrupting the wind patterns of the world and THAT is what is causing Global Warming? Start building your grass thatch huts and rendering fat for candles.
SamB
3 / 5 (2) May 17, 2017
So, that means we should drain the great lakes (and any other lakes for that matter) so that all that organic carbon can get out to the ocean. Or are 'natural' lakes somehow blessed?

If man dams a river or a landslide dams a river, I really don't see how this organic carbon would know the difference.
antialias_physorg
5 / 5 (5) May 17, 2017
Listening to and reading articles like this tell me the Author(s) consider the Human Race to be the cause of everything bad that happens in the world.

Then you should probably read it again, because none of what you claim is said by the author(s).

what happens when we FINALLY discover that, aside from killing millions of birds, the wind generators are disrupting the wind patterns of the world and THAT is what is causing Global Warming?

Since global warming was happening before we started to put up wind generators in numbers: what are you babbeling about?
(Hint: Warming is a result of putting excess energy from sequetered sources into the system, wind generators are taking it out of the system and the use of that energy is putting it back. Windpower is a close to a zero sum game)
mtnphot
not rated yet May 20, 2017
If man dams a river or a landslide dams a river, I really don't see how this organic carbon would know the difference.

A lot of the ocean's nutrients come from rivers. if they are dammed the carbon may be sequestered, along with phosphorus and other nutrients required to fix carbon in the ocean.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.