Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Small dams on Chinese river harm environment more than expected, study finds

29.05.2013
A fresh look at the environmental impacts of dams on an ecologically diverse and partially protected river in China found that small dams can pose a greater threat to ecosystems and natural landscapes than large dams.

Although large dams are generally considered more harmful than their smaller counterparts, the research team’s surveys of habitat loss and damage at several dam sites on the Nu River and its tributaries in Yunnan Province revealed that, watt-for-watt, the environmental harm from small dams was often greater—sometimes by several orders of magnitude—than from large dams.

Because of undesirable social, environmental, and political implications, the construction of large dams often stirs controversy. Current policies in China and many other nations encourage the growth of the small hydropower sector. But, “small dams have hidden detrimental effects, particularly when effects accumulate” through multiple dam sites, said Kelly Kibler, a water resources engineer who led this study as part of her PhD research while at Oregon State University in Corvallis. “That is one of the main outcomes of this paper, to demonstrate that the perceived absence of negative effects from small hydropower is not always correct.”

She and Desiree D. Tullos, also a water resources engineer at Oregon State and Kibler’s PhD advisor, report their findings in a paper accepted for publication in Water Resources Research, a journal of the American Geophysical Union. Kibler now works as a researcher at the International Centre for Water Hazard & Risk Management in Tsukuba, Japan, and as an Associate Professor at Japan's National Graduate Institute for Policy Studies in Tokyo.

To compare the impacts of small and large dams, Kibler investigated 31 small dams built on tributaries of China’s Nu River and four large dams proposed for the main stem of the Nu River. She assessed the environmental effects of these dams in 14 categories, including the area and quality of habitat lost, the length of river channel affected, the amount of conservation land impacted, and the landslide risk. Because information regarding large dams is restricted under the Chinese State Secrets Act, Kibler modeled the potential effects of the four large dams using publically-available information from hydropower companies, development agencies, and academic literature.

After evaluating data from the field, hydrological models, and Environmental Impact Assessment reports about the small dams, Kibler and Tullos concluded that impacts of the small dams exceeded those of large dams on nine of the 14 characteristics they studied.

One particularly detrimental impact of the small dams observed in this study is that they often divert the flow of the river to hydropower stations, leaving several kilometers of river bed dewatered, Kibler explained.

From its headwaters in the Tibetan Plateau, the Nu River flows through China, Myanmar (Burma) and Thailand. “While the number of small hydropower dams in operation or planned for tributaries to the Nu River is unreported,” the authors note in this study, “our field surveys indicate that nearly one hundred small dams currently exist within Nujiang Prefecture alone.”

Thirteen large hydropower dams are proposed for the main stream of the Nu River in Tibet and Yunnan Province in China. “No large dams have been built, but there have been reports that site preparations have begun at some proposed dam sites,” Kibler said.

Environmental, social, and economic factors make the Nu River basin extremely sensitive to hydropower installations. In addition to supporting several protected species, the region is home to a large proportion of ethnic minorities and valuable natural resources, the authors report in the study. Parts of the Nu River are also designated as a World Heritage site and the Nature Conservancy and Conservation International have delineated stretches of this river and its tributaries as biodiversity hotspots. But proposed hydropower projects are threatening these statuses, according to Kibler.

While large hydropower projects are managed by the central government, and both large and small hydropower projects undergo environmental impact assessments, decisions about small hydropower projects are made at a provincial or other regional level and receive far less oversight, Kibler and Tullos state in their paper.
Small dams in China “often lack sufficient enforcement of environmental regulations” because they are “left to the jurisdiction of the province,” said Guy Ziv, lead scientist for the Natural Capital Project, an organization which develops tools to assess and quantify natural resources, and a researcher for the Woods Institute for the Environment at Stanford University. This study, he added, is “an important contribution to the field of natural resource management.”

The lack of regulation paired with a dearth of communication between small dam projects in China allows for the impacts to multiply and accumulate through several dam sites, the study authors write.

In order to mitigate the detrimental effects of small dams, there is a “need for comprehensive planning of low-impact energy development.” Kibler and Tullos note.

Policies supporting growth in the small hydropower sector are often crafted at the national or international level, Kibler noted. For example, many of the small dams investigated in the new study were supported by the Kyoto Protocol, a 1997 agreement to reduce greenhouse gas emissions.

“The lack of comprehensive analysis regarding cumulative impact of small hydropower,” Kibler said, “is a significant research gap with important policy implications.”

The National Science Foundation funded this work.

Notes for Journalists

Journalists and public information officers (PIOs) of educational and scientific institutions who have registered with AGU can download a PDF copy of this accepted article by clicking on this link: http://onlinelibrary.wiley.com/doi/10.1002/wrcr.20243/abstract

Or, you may order a copy of the final paper by emailing your request to Sarah Charley at scharley@agu.org. Please provide your name, the name of your publication, and your phone number.

Neither the paper nor this press release are under embargo.

Title:

Cumulative biophysical impact of small and large hydropower development, Nu River, China

Authors:
Kelly M. Kibler Water Resources Engineering, Oregon State University, Corvallis, Oregon, United States; Desiree D. Tullos Biological & Ecological Engineering, Oregon State University, Corvallis, Oregon, United States.

Contact information for the author:

Kelly Kibler, Email: kibler55@pwri.go.jp, Phone: +81-29-879-6809

Peter Weiss | American Geophysical Union
Further information:
http://www.agu.org
http://www.agu.org/news/press/pr_archives/2013/2013-22.shtml

More articles from Earth Sciences:

nachricht Scientists shed light on carbon's descent into the deep Earth
19.07.2017 | European Synchrotron Radiation Facility

nachricht Thawing permafrost releases old greenhouse gas
19.07.2017 | GFZ GeoForschungsZentrum Potsdam, Helmholtz Centre

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

Vortex photons from electrons in circular motion

21.07.2017 | Physics and Astronomy

Topologische Quantenchemie

21.07.2017 | Life Sciences

Pulses of electrons manipulate nanomagnets and store information

21.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>