(April 18, 2011) Chinese geologists warn that hydropower development on the Nu River will pose grave risks to those living downstream.
By Zhang Ke
China Business News (Diyi caijing ribao)
Originally published 24 February 2011
Translated by Probe International
Xu Daoyi, senior researcher for the Institute of Geology, China Seismological Bureau, and his old classmate Sun Wenpeng, senior researcher for BRIUG (Beijing Research Institute of Uranium Geology), sat in an office in the Institute of Geology, China Seismological Bureau. They both looked extremely concerned. Although these two geologists were both over seventy years old, they expressed their thoughts quickly and clearly on the proposed large-scale hydroelectric development in the Nu River when interviewed by reporters from the China Business News.
“It would be unconscionable if we didn’t ask the younger generation to stop,” Xu Daoyi told the author, when asked about building dams on the Nu. Having accidentally found out about the power company’s plans for large-scale development of the Nu River, they said, “Once we learned about it, our first reaction was to immediately write a letter to the central government to express our opinions.”
“Our views originate in our understanding of the fault belts and seismic activity in the area, and have a purely academic focus. Our opinions do not reflect having been requested by anyone to carry out this investigation. We are simply doing this through our own spontaneous initiative,” Xun Wenpeng said.
Later, Sun Wenpeng and Xu Daoyi gave the reporter a copy of the letter they had written to the central authorities. Signatories on the letter also included Professor Li Dongxu of the China University of Geosciences, Han Meng, researcher from the Economic Research Institute of the Chinese Academy of Social Sciences, and Zhu Ming, research fellow from the Geology and Geophysics Research Institute in the Chinese Academy of Sciences.
The two senior geologists told the reporter that the letter had already been sent and that over the years, they had sent more than twenty letters containing similar recommendations to the authorities, few of which had received responses.
At the end of January this year, Shi Lishan, the deputy head of the New and Renewable Energy Division of the National Energy Bureau (of the National Development and Reform Commission), said that preliminary evaluations of damming the Nu River were in progress and that the river would definitely be exploited. This was the first clear declaration of intent to dam the Nu River by the National Energy Bureau.
In 2004, the National Development and Reform Commission sent a report titled “Report on Hydropower Plans for the Middle and Lower Reaches of the Nu River” to the State Council. At that time, leaders in the State Council declared that “in large scale hydropower projects such as this, which attract a high level of public attention and differing views about its environmental impact, we should investigate with great care and make decisions on a scientific basis.” Potential hydro projects on the Nu River were shelved because of this.
The original proposal submitted to the NDRC was to build 13 dams on the main channel of the Nu River with a total installed capacity of 21,320 MW, and annual electricity generation of 102.96 TWh.
“We recently made a special trip to the area of the Nu River where we did an on-the-spot examination of the geological conditions along the river banks, of the topography, landforms, the mud and rock flows and also of the tunnels in the vicinity of the dam sites,” said Sun. “Considering the unique complexity of its geological background, the severity of its geological disasters, and the possible effects that staged hydropower stations could have, we have concluded that it would be geologically extremely risky to build dams on the Nu River,” added Sun Wenpeng.
Sun Wenpeng went on to explain that many experts in academic circles agreed that the Nu River area is uniquely geologically fragile and unstable (new fault movements have been intense and there is a high level of fracturing), that the Nu River fault belt, in particular, is extremely active, and that the Nu River (the section of it in Yunnan Province) flows along a fault line.
That fault belt along which the Nu River flows is the main fault in the entire river system. It is the main geological factor limiting the options for staged hydropower dam sites and affecting decisions about the safety of the staged electricity stations. “Those formulating the plans for hydropower development have not demonstrated sufficient caution. Their risk evaluation—performed by the dam planners—has focused primarily on a narrow evaluation of each dam site in isolation.”
Sun Wenpeng and Xu Daoyi are of the opinion that if public safety were a priority, the following key factors would be considered very seriously.
- The Nu River is an area where intense new tectonic movements and high magnitude earthquakes (7-8 on the Richter scale) are taking place with a high level of frequency.
- It is an area where many geological disasters such as mud-rock flows occur.
- Recent tectonic movements have intensified and earthquakes and geological disasters have markedly increased in strength.
- The interaction of extreme climate events[i], tectonic movements and earthquakes has led to an increase in the likelihood of geological catastrophes.
Xu Daoyi says that in the last 200 years, and especially in the last 60 years, there have been frequent earthquakes inChina’s southwest region. These have included:
- 8.6 magnitude earthquake in eastern Tibet near the Nu River in 1950;
- 7.3 Longling earthquake in Yunnan in 1976;
- 7.4 Lancang-Mekong River earthquake and the 7.2 Gengma earthquake in Yunnan in 1988;
- 7.3 earthquake on the Sino-Burmese border in 1995;
- 7.0 Lijiang earthquake in Yunnan in 1996.
All of these have occurred on the Nu River or in nearby areas. The 20th Century saw an increase of seismic activity in Yunnan (including the Nu River area) with periods of frequent large-scale earthquakes.
Xu Daoyi said, “We think that large earthquakes in the southwest and powerful earthquakes in Yunnan in particular have significantly increased in the last hundred years. It is a fact that can’t be ignored when one examines the geological stability of the area and the seismic trends.” He said that to date he does not know of any geologists or seismologists who deny that large earthquakes will occur in the Nu River area in the 21st Century (and they will be much larger than those which have occurred in the last few decades).
As for the question about the banks of the Nu River being the location of frequent geological disasters, Xu Daoyi said that while doing their investigation, they found dangerous sections in reservoirs everywhere; sections that were crumbling or experiencing mud-rock slides and landslides. This was the case for the Songta hydropower station in the upper reaches of the Nu River inside Tibet to the Guangpo hydropower station (also on the Nu) near the Sino-Burmese border (The only exception was the Bingzhongluo pumped water power station).
According to the 1995 publication “Scatter Diagrams of Chinese Geological Disasters,” the section of the Nu River from Liuku to Maji was considered as an “area of severe incidence,” predominantly of mud-rock flows. The Nu River is an area with a high potential for complex natural disasters.
“We are very concerned, and wonder if this important information has been mentioned in the relevant authority’s (Nu River Hydropower Development) plans or reports?” Xu Daoyi said. The Yunnan Nu River Lisu minority group autonomous prefecture covers an area of 14,703 square kilometers, 98% of which is comprised of high mountains and gorges with frequent landslides and mud-rock flows. After the Puladi mud-rock flow happened in Gongshan County on August 18, 2010, Duan Yueqing, the prefectural committee secretary, admitted that the Nu River prefecture also had 762 other areas with landslides and mud-rock flows at that time.
“The third key fact is that, at present, the whole world is going through a period of frequent geological upheaval and seismic activity.” Xu Daoyi said that at the beginning of the 21st Century we entered a period of strong seismicity, geological disasters, and unusual climatic conditions (extreme weather), which has not abated yet. In recent times the global occurrence of many large, magnitude 7 to 8 earthquakes, including the 2008 Wenchuan earthquake, is evidence of a trend of increasing tectonic movement around the globe.
The author notes that there has been a long history of debate about hydropower development on the Nu River, but this is the first time that a core group of experts, such as Sun Wenpeng and Xu Daoyi, have taken a strong public stand.
“We would also like to emphasize that the Nu River has some very distinctive geological problems. Its geological disasters are particularly hazardous precisely because it is a geologically unique and unusual area,” Sun Wenpeng told this reporter.
Satellite pictures show that the Yunnan fault area lies within an especially strong and intense rupture zone of new tectonic activity. Construction of a cascade of hydropower stations and large dams that interrupt the flow of the river will of necessity span the fault rupture zone (or lay within the rupture zone). But the fault along which the Nu River flows is still active. According to the statistics, the large fault on the Nu River and two or three other faults over 100 meters in width are clearly visible in numerous cross sections of the Nu River valley. In addition there are up to thirty small ruptures. The whole fault zone is between 400 to 1000 meters in width, and is very hazardous.
Rainfall in the Nu River basin area is plentiful and concentrated in the rainy season, in particular from June to August. Sudden torrential downpours in areas with numerous geological faults, steep valleys and crumbling river banks can turn into huge floods.
“Development of staged dams on the Nu River could exacerbate the risk of large geological disasters.” The two geologists said that to build staged dams that obstruct the river, there must be a thorough understanding of the above mentioned characteristics and geological risks. Even if an earthquake happened at a distant location, it could still trigger an unimaginable geological catastrophe in this area, such as mountain collapses, landslides and mud-rock slides.
“We cannot ignore the existence of a composite series of serious problems along the river: climatic, geological, engineering and many different kinds of issues, that when linked together could turn into a chain of tragedies, magnifying the destructiveness of the original disaster.
What would the basic effect of this destruction be? Xu Daoyi thinks:
One possibility is that if there were an accident such as catastrophic dam failure in one large dam that would cause many other downstream dams to collapse. If one of the dams (especially one on the upper reaches) were damaged, billions of cubic meters of river water carrying large quantities of mud and rock would flow straight down in torrents along an essentially narrow and straight river valley which has a steep gradient, causing devastating destruction in the lower reaches of the river.
Another possibility is that a high level of water could destabilize the banks of a reservoir, leading to large-scale landslides. These would in turn result in huge waves on the reservoir which could constitute a threat to the dam structures and to earth embankments. It could also pose a threat to water conservancy or irrigation works as well as the lower reaches of the river. The huge mudslide that took place in Zhouqu is an important lesson for the authorities who are currently considering the geological risks involved in hydropower construction on the Nu River.
The debate over hydropower dams will continue
In their letter to the higher authorities the geologists wrote, “The fault displacement cannot be prevented along the Nu valley, no matter how solid the reinforced concrete on the dam is; neither will anyone be able to prevent the massive collapses, landslides and mud-rock flows which have been occurring along the banks of the Nu River.”
Technological success in building enormous dams over the last decade in China should not make people complacent about constructing a large hydropower dam across a river right on an active fault with ongoing seismic activity. There has been no successful precedent in human history for constructing dams in a tectonic environment such as this.
In recent years, disasters such as the large Wenchuan and Yushu earthquakes (which claimed 2200 lives) and the huge Zhouqu mud-rock slide have come just as we are being warned that we are going through a period of frequent massive geological upheaval and extreme weather conditions. Xu Daoyi said that the probability of unprecedented geological disasters and earthquakes occurring in the area of the Nu River in the first half of the 21st Century would still be extremely high, even without the additional problems caused by man-made environmental destruction.
The two senior geologists suggested, “The danger of earthquakes and geological calamities happening in the Nu River area is a particularly important issue which should be discussed more widely, with more experts invited to investigate and research the issue.” They think that relevant leaders and authorities should develop a more scientific approach by encouraging different opinions to be heard and debated among a wider audience and at higher levels. Unless the issue is thoroughly debated and scientifically researched and investigated, any form of dam construction without prior approval should be prohibited.
Other experts, hydropower developers, and local officials in the Nu River region, meanwhile, dismiss the warnings and suggestions made by the two senior geologists.
Lu Youmei, former general manager of the company called Three Gorges Group, indicated that hydropower development in the Nu River has the following advantages: the water volume from the main channel of the Nu River is plentiful and steady, the gradient of the river bed falls steeply, topographical and geological conditions are good for hydropower development and there are few migrants to be relocated. In his opinion, building hydro power stations in the Nu River could be a win-win situation for natural resource development as well as for environmental conservation, as long as the environmental issues are taken seriously and a scientific approach to development is adopted.
Pan Jiazheng, former chief engineer of the former Ministry of Water Conservancy and Electric Power said that a few power stations built on the Nu River will not change the magnificent sight of flood water roaring and surging forward. The beautiful scenery of snow covered mountains, steep slopes, grasslands and torrents of water in the Nu River Gorge will still be there and the diversity of the geology, biology and scenery in the area where the three rivers merge will not be lost either.
In 2007, when the author was conducting interviews along the Nu River in Yunnan, he met the head of Nu River Prefecture, Hou Xinhua, who explained that the prefecture would resolutely follow the strategic plan to build a national hydropower base in the Nu River to become an “economically powerful prefecture rich in minerals and electricity.”
He said, “The people of Nu River earnestly hope to shake off their poverty and become better off. They are beginning to have the capacity to improve their homeland. Nobody has the power to deprive them of their right to build a new countryside.”
According to Hou Xinhua, the prefecture put forward a proposal in early 2007 called “Three Big Goals”: to build a national hydro power base, to build a national non-ferrous metal base and to develop tourist sites such as the Nu River Gorge and the area where the three rivers meet.
“However this doesn’t mean that one can go blindly developing hydropower in areas where there are serious geological risks,” said Xu Daoyi.
“Nevertheless,” says Xu Daoyi, “this doesn’t mean that one can go blindly developing hydropower in areas where there are serious geological risks.”
[i] Such as heavy rains causing flooding and subsequent landslides and mud-rock slides.
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Categories: Three Gorges Probe