Are the dams the cause of damaging earthquakes ?
Posté par ITgium le 27 September 2014
“The dam sustainability depends on its sediment treatment”.
jùn mǎ (俊 马) *
There is some speculation that the earthquake occurred in China’s Sichuan originate from the complicated dams issues.
The dams have deep environmental implications.
Hydropower, China’s largest source of renewable energy.
In recent years, because of the coal production reduction[1] China use of hydropower increases, now’s the largest source of renewable energy.
For the record, it is noted that the Chinese government and companies have pledged to invest $275 billion in pollution abatement by 2015.
But there has long been speculation that some of China’s deadly earthquakes were caused by nearby dams and filling of reservoirs.
A dam is not a neutral infrastructure.
Hustling the environment, it modifies dramatically the sediments distribution. Trapped into artificial lakes or tanks, sediments accumulation gives birth to serious problems.
Sediments constitute a real danger in case of seismic trouble. So, it is not exaggerated to affirm that dam future depends on sediments solutions treatment.
Located in Hubei province, near the city of Yichang, the Three Gorges Dam is the largest of the world for water control and hydropower productivity.
Built up thanks to a deviation of the Chang Jiang River, its a reservoir covers a surface area of 1084 km2. The hydroelectric power plant consists of two sections: on the left, 14 turbo generators, on the right, 12 turbo generators. The set offers a powerful 18720 MW. According to experts, the dam is expected to provide 10% of China electricity consumption.
Sometimes quoted as a sustainable development project, the Three Gorges Dam disrupts and alters the sediment cycle.
Upstream the river, crossing the Tibetan plateau, sludge inflates the Chang Jiang. Due to an intense deforestation and desertification, soil is friable. Weakened banks allow landslides. In addition to land overuse, sediment decreases the water velocity. Each year, 500 million tons are deposited in the river gorges, including the retention lake.
Furthermore, sediments accumulation exerts a strong pressure on the structure that could lead to its cracking.
Because the Eurasian and the Yangtze plate are not stable, the risk of an earthquake does exist. In recent years, low-magnitude earthquakes have produce landslides.
Areas near Hubei’s Three Gorges Dam (2012-2013), the world’s largest hydropower project placed on the Yangtze River, saw 3,400 earthquakes registered during this period.
Dam and earthquake correlation
By analyzing publicly available crude seismic data, I have found a rough correlation between the filling of reservoirs used to generate hydropower and seismic activity in the surrounding area, which bolsters existing research.
Some examples :
Ludian County earthquake (Aug. 3, 2014)
There’s great speculation as to whether this earthquake, which killed nearly 600 people, was linked to two nearby dams, Xiangjiaba and Xiluodu. Some researchers think the dams couldn’t have caused the quake because water—which can induce quakes—wouldn’t have been able to reach the initial 12km rupture; however, others said that the sheer weight of the reservoir could rupture the critically stressed fault.
Sichuan and Yongshan County earthquakes (April 20 and Aug. 30, 2013)
Caused by faults directly below the Xiluodu reservoir, these quakes are most likely to have erupted due to Xiluodu, according to geologists.
Sichuan earthquake (May 12, 2008)
With a death toll of around 70,000 people, geologists debate whether it was linked to the filling of the Zipingpu reservoir in Sichuan province. Some researchers think that the reservoir partially triggered the quake; others said it expedited the earthquake’s coming.
Should China’s government stop operating its dams to reduce life-threatening quakes, even if it requires losing an important clean energy source?
To challenge this situation, one of solution is the sediment removal.
But, given their volume, it requires considerable resources. Considering the Three gorges dam, downstream the river sediment transportation looks like a titanic operation, quite impossible to manage. Another answer is to valorize directly the sediments but they are heavily contaminated.
The dam construction has been swallowing 1300 coalmines, 178 garbage dumps, 1500 slaughter, etc. In fact, sediment offers an unprecedented variety of harmful heavy metals, toxic microorganisms, and so on. Their eventual recovery in construction materials suggests chemical treatments (for instance, their encapsulation).
Dehydrating process exists as those developed by the Franco-Chinese company Paneurochina SEDIGATE but given their enormous volume, the operation is likely unworkable.
The so-called Three Gorges sustainability depends on the sediment treatment.
Long underrated, the issue has been taken into account by the Chinese authorities, which fears the earthquake are related with that
[1] which makes up 70% of China’s energy
* Francois de la Chevalerie
Publié dans China Sediment issues, Dam & Earthquake, Earthquakes and Sediment in China | Pas de Commentaire »