A damming trend

A damming trend
Hundreds of dams are being proposed for Mekong River basin in Southeast Asia. The negative social and environmental consequences -- affecting everything from food security to the environment -- greatly outweigh the positive changes of this grand-scale flood control, according to new research by Michigan State University. Credit: Michigan State University

Hundreds of dams are being proposed for Mekong River basin in Southeast Asia. The negative social and environmental consequences—affecting everything from food security to the environment—greatly outweigh the positive changes of this grand-scale flood control, according to new research by Michigan State University.

The results, published in the current issue of Scientific Reports, are the first to tackle the potential environmental changes that the overall basin could experience from harnessing the region's hydropower.

"The Mekong River is one of the few large and complex river systems that remains mostly undammed," said Yadu Pokhrel, assistant professor of civil and environmental engineering and the study's lead author. "However, the rapid socio-economic growth, increasing energy demands and geopolitical opportunities have led to basin-wide construction of large hydropower dams."

In the basin's upper portion, dozens of mega dams are in the process of being built. In the lower region, hundreds of tributary dams are planned, and some larger ones also are being constructed.

While there are many positive effects of flood control, the researchers focused on the reduction of monsoon-driven floods that would be held back by the dams. These annual pulses provide much-needed water and nutrients to downstream regions.

"Any major alterations of the seasonal pulses could easily change the area's floodplain dynamics," Pokhrel said. "This could severely affect a wide range of ecosystems and undermine regional ."

One waterway in particular, the Tonle Sap River that connects the Mekong River and Tonle Sap Lake, is one of the world's most-productive freshwater fisheries. Monsoons flood the Tonle Sap and actually reverse the river's flow each year. This brings water and sediments from the Mekong River into the Tonle Sap River as well as Tonle Sap Lake.

During the dry season, the flow normalizes and the lake drains into its namesake river, which eventually dumps into the Mekong River.

"Flow regulations could disrupt the flood dynamics of the Tonle Sap River," Pokhrel said. "In fact, our models indicate that TSR flow reversal could cease completely if the Mekong River pulse is dampened by 50 percent and delayed by one month."

The team of MSU scientists who were part of this study included Sanghoon Shin, Zihan Lin and Jiaguo Qi. Dai Yamazaki, from the University of Tokyo, also contributed to this research.

Explore further

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More information: Yadu Pokhrel et al. Potential Disruption of Flood Dynamics in the Lower Mekong River Basin Due to Upstream Flow Regulation, Scientific Reports (2018). DOI: 10.1038/s41598-018-35823-4
Journal information: Scientific Reports

Citation: A damming trend (2018, December 14) retrieved 18 September 2019 from https://phys.org/news/2018-12-trend.html
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Dec 14, 2018
And since these poor Chinese have no civil or even human rights, this will proceed no matter the human cost.

Dec 14, 2018
This could...undermine regional food security

Um..., dams usually are accompanied by irrigation systems that distribute water from the reservoir behind the dam to farmers which...wait for it...INCREASES food security. Dramatically. Instead of waiting for seasonal floods to irrigate (or wash away) their fields, farmers can get a controlled flow of water for their crops over a much longer period of the year.

Dams provide numerous benefits to humans like flood control and reliable power and irrigation that vastly outweigh the consequences of changing the floodplain dynamics. Humans are remarkably adaptable. If river fishing is negatively impacted, they will quickly develop other systems of food production and distribution to replace it.

Contrary to the bizarre ideals of environmentalists, dams are a good thing. 21st century agriculture and power production are preferable to those of the 2nd century.

Dec 14, 2018
In reality the greenies will only classify hydroelectric power as renewable when it is part of a solar pumped storage system. The renewable industry will stop at nothing in order to maximize their control of our power sources.

Dec 14, 2018
This will probably go ahead anyway; but at least they were warned and can't say nobody told them what it would cost.

Dec 14, 2018
The Aswan High Dam's silt retention seems to have caused collapse of the coastal fishery, and the lack of sediment at the coast is allowing erosion and subsidence...

Good for archaeologists as erosion unearths long-buried stuff, bad for the locals...

Dec 15, 2018
Asians don't care about the environment. Coal-burning, land pollution, air pollution, billions of tons of plastic being dumped or flushed into the oceans. Most of all of this from Asia. Why should they care about the negative impact of dams?

Dec 15, 2018
@ThorazineBoi shows its racism.

Dec 15, 2018
Yeah, the tb is quite the hypocritical bigot. Considering the agitprop from the tb's cult of the atomic priesthood?

Accusing anyone else of poisoning the Earth's Biosphere is an exercise in self-ridicule.

I suspect tb is just jealous that the Chinese might be more competent at poisoning the World, than his claque of suicide.

Dec 15, 2018
billions of tons of plastic being dumped
See - those dirty Asians - they dump all their plastics - cuz they are just like animals (sarcasm). The fact that the west has been using China as a dumping ground for waste plastic - is of course not a fact in the book of Conservative dogma - https://www.nytim...ban.html

Lots of youtube on the subject - https://www.youtu...mhmLVL9U

Dec 16, 2018
Doesn't flood control generally INCREASE food security?
They argue that the floods also being 'sediments' that I assume they imply boost food production but then you must measure that up against with the potential damage floods do to crops and the fact floods aren't essential for food production because elsewhere in the world floods aren't needed for food production thus is would surely be just a trivial task to change and adapt the farming practices and food production to work just fine without such floods.
Thus their assertions seem to me to be based on flawed thinking.
They should reassess the effects of dams but this time take into account that farmers aren't complete morons and will adapt.

Dec 16, 2018
Rice is kinda funny that way. I hadn't actually thought about that; perhaps this has impacts the researchers haven't considered on rice cultivation, depending on the exact techniques in use. Perhaps more consideration should be given to this. The paper is open source; I'll review it and see if this has been taken into account by the authors.

Dec 16, 2018
OK, I had a look at the actual paper and these guys don"t have their act together. They mention rice one time in the whole paper and I don't get the impression they did anything but skim the literature and take a figure they found somewhere. Nor that they understand the importance of rice in Asian cultures, not just as a cultural thing but as a main source of food for many Asians. So overall I'm not impressed. The authors seem to think that hydroelectric power is the only justification, but it seems rice growing is also a goal of these projects. This looks like politics invading science.

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