Technology innovation 新技术 创新

Earthquakes

“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.

Three Gorges dam

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.

Dam scheme

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.

Tectonic_map_of_China

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?

Dredge

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

* Francois de la Chevalerie

Port of Shanghai

China Clean harbour and Sustainable Development : the sea mud topic ! *

François de la Chevalerie jùn mǎ 俊 马

In outer harbours, rejections, waste and sand constitute an ungrateful material sometimes called “sludge” or “sea mud”. It could retain hydrocarbon, nitrogen, phosphorus, and heavy metals.

Sea mud could represent a real danger for environment as well as atmosphere emissions. All ports are concerned, small or big one, in particular, arsenals. In addition to natural erosion, the traffic expands sediments accumulation.

Port of Tianjin

Each day, expensive dredging operations gave access to navigation.

Then sea mud has to be rejected in dedicated sea areas with unknown ecosystem consequences.

Sometimes sea mud’s awfully contaminated take place in ground storage. If the sea mud is not buckled in tight boxes, it could have also ecological consequences. In one case or the other, those solutions have nothing to do with the idea of “a clean port”.

How to think the sea mud differently?

Today sea mud treatment is rare and always related to small volume, mainly contaminated sediments.

Once decontaminated, sea mud is rejected into the sea. A better answer consists in the transformation of the sea mud into Eco-building materials (roads embankment, kerbs, breeze blocks, moulded, flagstones, bricks).   

Port of Tianjin

All over the world, the stake is crucial.

Actually, we experienced an increasingly shortage of aggregates from alluvial materials. In the same way, the careers close. Considered polluted, sometimes dangerous, their time is counted.

The sea mud constitutes an alternative, a “renewable material”!

Today Chinese develop projects of valorisation.

According to reports, the methods remain artisanal, but the Chinese has decided to make it a major industrial project.

Already, in southern China, bricks are manufactured. In northern China, roads embankment integrates sea mud.

Dam

François de la Chevalerie jùn mǎ 俊 马 and Professor Levacher (University of Caen)

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, it is structured around a reservoir with a surface area of 1084 km2.

Bigger than the Itaïpu Dam (Brazil), 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.

D

Sometimes quoted as a sustainable development project, the Three Gorges Dam suggests anxiety.

In addition to pollution and Eco system damage, the 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 permit landslides. Coupled with land overuse, sediment decreases the water velocity. Each year, 500 million tons are deposited in the river gorges, including the retention lake. At the work achievement in 2009, the pressure affected already its hydroelectric potential up to 50%.

Furthermore, sediments accumulation exerts a strong pressure on the structure and 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. In the event of a large-scale one, the Dam breaking could happen.

Downstream the river, sediment played before a role of natural fertilizer. Because of their decrease, agrochemicals use should be now required. So it will intensify water pollution. Already levels of phosphorus and nitrogen are twenty times higher than the standards. In addition, the sediment reduction may push back the River delta. Moreover, in winter, it accelerates saline groundwater within the delta.

three gorges dam

To challenge this situation, the solution could imply the sediment removal.

Given their volume, it requires considerable resources. Downstream the river sediment transportation looks like a titanic operation, quite impossible to manage.

Another answer is to valorise 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 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 have agreed with a 1.5 billion $ a budget to grant an efficient solution to the sediments future.

Dam’s issues

François de la Chevalerie jùn mǎ 俊 马

Obviously, a dam main duty is to control floods downstream of a river flow or a tide. Frequently, it supports the cultures irrigation. Sometimes it moderates natural flood disasters.

Under constraints conditions, it authorizes electricity production. In history, dam’s construction was often celebrated as “a revenge on nature”.

“Our country will never be the same!” proclaimed President Roosevelt while launching the New Deal dams project. “China shall overcome the Chang Jiang (Yangtze)!” expressed today Chinese officials.

Dam’s issues

With nature, arrogance is a poor adviser.

A dam is not a neutral infrastructure. Hustling the environment, it modifies the sediments distribution. Trapped into artificial lakes or tanks, sediments accumulation gives birth to serious problems.

Concerning the coastal dams, it affects the navigation channels and the fisheries areas. Deposits worsen water quality, entropic activities and in a latter future lead to strongly climate change.

In France, congested sediments into the tide Rance dam had been deteriorating its estuary since many years. Sediments into the Arzal dam in Brittany are up to 22 million m3, nearly 50% of that existing in the entire France harbor.

In China, the newly Three Throats dam could severely damage the ecosystem because sedimentary evolution remains unknown. In addition, sediments constitute a real danger in case of seismic trouble. In large cities, underground water quality could be also contaminated. So, it is not exaggerated to affirm that dam future depends on sediments solutions treatment.

D

However, it is quite impossible to settle down a scientific model for all sedimentary layers. Each dam maintains a specific relation with its environment.

For each, a sedimentary hydro examination could eventually model it. One option consists to transport sediments outside the dam area.

But immersions operations couldn’t be carried out without taking into consideration ecosystem safeguarding laws. In land, deposits evacuation is not easy as well as very expensive.

The solution could come from China. Confronted with vast sediments quantities inside harbor and estuaries, China brings an industrial answer with the sediments valorization into eco building materials (roads embankment, kerbs, breeze blocks, molded, flagstones, bricks).

The so-called sludge project associates building companies, universities and research centers. For several years, genius civil departments have worked on sediments mechanical performances.

Little by little, technique improves. Recently, the Popular National Assembly has outlined that now China will become a world-engineering laboratory. Construction huge market meets that challenge. In Europe, increasing concern, related to serious sediments problems, impose also a radical solution to preserve the ecosystem.