Is The Three Gorges Dam on the Brink of Collapse?

[ronwagn + 6,290]

https://www.theepochtimes.com/chinas-largest-dam-on-the-brink-of-collapse-as-flooding-ravages-country-expert_3401097.html

China and the U.S.A. both have a lot of problems right now. It would be better if they just got along and dealt correctly with their own problems rather than act like two raging bulls hitting heads. Is fairplay out of the question?RCW 

 

China’s Largest Dam on the Brink of Collapse as Flooding Ravages Country: Expert

BY EVA FU

 

June 24, 2020 Updated: June 24, 2020

 

 

 

[Marcin2 + 726]

@ronwagn Could you Please insert the whole article. The site requires sign up to read it.

[SUZNV + 1,197]

https://www.asiatimesfinancial.com/flood-alert-at-three-gorges-dam

Flood alert at Three Gorges Dam

China faces its worst floods in 70 years after weeks of heavy rain; disasters have been declared in 24 areas, including the upper reaches of the Yangtze; 7,300 homes have collapsed and damage exceeds 20.7 billion yuan

by Chris Gill

 

An aerial view of Three Gorges Dam, which has a reservoir 170 metres deep, in Zigui county, Yichang city, in central China's Hubei province. File photo taken in October 2019: Wang Gang / ImagineChina via AFP.

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(ATF) A flood alert has been raised near China’s famous Three Gorges Dam after the country suffered its heaviest rainfall in 70-80 years. Torrential rain has been causing chaos throughout China’s southwest this month, with many rivers overflowing and mass evacuations.

 

Heavy rains over the past three weeks have led to disasters being declared in 24 provinces and municipalities, especially near the upper reaches of the Yangtze River and the Three Gorges Dam.

This is reportedly the largest flooding since 1949 and has caused serious challenges to the world's largest dam.

In Chongqing, authorities dredged 100,000 tonnes of silt overnight as levels rose.

Three Gorges is located in Sandouping Town, near Yichang City in Hubei Province in central China. It is 38 kilometres from the downstream Gezhouba Water Conservancy Project at the eastern end of the Three Gorges Reservoir. 

Qijiang Online, the media outlet in the area, quoted Zhao Yunfa, deputy chief engineer of the overflow dispatch communications centre at the Three Gorges Project, who said: "The flood storage capacity of the Three Gorges is limited. Do not pin your hopes on the Three Gorges Dam."

Zhang Shuguang, director of the Three Gorges Corporation Hub Management Bureau, also said that flood control measures for the entire Yangtze River Basin could not rely on a Three Gorges Dam to dominate the flood.

Construction on the dam began in 1994 and ended in 2006 after total investment of about 95.5 billion yuan (US$13.5 billion). The dam itself is 2,335 metres long and has an elevation of 185 metres. The second part of the scheme was a water diversion project. The dam has 32 turbine generator units and power generated by its hydropower station exceeded 100 billion kilowatt hours in 2018, a world record for a single facility.

The dam caused considerable controversy as it displaced over a million people and submerged large areas of the Qutang, Wu and Xiling gorges for about 600km – creating a deep reservoir that ocean-going freighters can navigate for 2,250km inland from Shanghai on the East China Sea to the inland city of Chongqing. 

The heavy seasonal rain this month has swamped 24 provinces and municipalities in southern and central China, affecting more than 85 million people and causing damage put at 20.7 billion yuan so far.

Zhang warned that the largest flood since 1949 may occur this year, as rainfall in the dam's catchment area – it has a reservoir up to 600km long – upstream of the dam poses a serious challenge.

Many plateaus in southwestern Sichuan Province have experienced heavy rain for 24 hours since June 16, and this was expected to continue in some parts of Sichuan until the 23rd (today).

Heavy rain in the upper reaches of the Qinhuai River in Jiangsu Province over the past few days totalled about 280 millimetres, which is equivalent to about 280 litres per square metre (or 11 inches on the old scale). This prompted authorities to issue strong rainfall warnings.

The State Flood Control and Drought Relief Headquarters, which is in charge of national flood control and drought relief work, said that from the 15th, floods had struck 852 provinces, autonomous regions, and municipalities in Guangdong, Guangxi, Hunan, Jiangxi, Guizhou, and Chongqing, causing 7,300 houses to collapse.

The Ministry of Water Resources said that 148 rivers had exceeded warning levels. For the first time in history the Chongqing section of the Qijiang River Basin issued a red warning, signifying a flood of more than 10 meters.

An estimated 400 million people live downstream of the Three Gorges Dam.

[Dan Warnick + 6,100]

Hogwash! 

I have stood at the base of that dam, on both sides of it.  I have been inside the power turbine tunnels.  I have walked in the overflow channels, driven/walked in the ship elevator, log and debris release, sludge abatement areas, and on top of it.  I did all of that during its construction and my host was the CEO of an Chinese/Italian/German/American/British consortium that had over 700 expat families living and working on site for the duration of its construction.  The designs were the result of many great minds from around the world coming together.

All of the "threats" that are being trumpeted now are exactly what the dam was designed and built to not only withstand, but far exceed.  It is not lost on me that mixed among the rhetoric about the dangers of the flooding right now are the mentions and reminders of the "great ecological damage"  and "human displacement" the dam was responsible for when it was constructed.  I have to ask myself why these complaints would be raised again during a time of political stress both within the country and around the world.

Hogwash!  That dam is as safe or safer than any dam in the modern world.

[LiamP + 168]

What's the deal with that year 2009/year 2018 split pic? Has someone just made it look all wobbly in photoshop to try to suggest it's about to collapse?? Lol!

Edited June 25, 2020 by LiamP

[Marcin2 + 726]

Since 2008 China builts a lot of other dams on Yangtze river and tributaries including huge Xilodu dam. China is super safe against any flood. The Article ( as usual at epoch) is just nonsense.

[Eyes Wide Open + 3,555]

1 hour ago, LiamP said:

What's the deal with that year 2009/year 2018 split pic? Has someone just made it look all wobbly in photoshop to try to suggest it's about to collapse?? Lol!

Elastic cement? Brave new world but then again there was the Russian/Trump event...go figure.

[Ward Smith + 6,615]

3 hours ago, Dan Warnick said:

Hogwash! 

I have stood at the base of that dam, on both sides of it.  I have been inside the power turbine tunnels.  I have walked in the overflow channels, driven/walked in the ship elevator, log and debris release, sludge abatement areas, and on top of it.  I did all of that during its construction and my host was the CEO of an Chinese/Italian/German/American/British consortium that had over 700 expat families living and working on site for the duration of its construction.  The designs were the result of many great minds from around the world coming together.

All of the "threats" that are being trumpeted now are exactly what the dam was designed and built to not only withstand, but far exceed.  It is not lost on me that mixed among the rhetoric about the dangers of the flooding right now are the mentions and reminders of the "great ecological damage"  and "human displacement" the dam was responsible for when it was constructed.  I have to ask myself why these complaints would be raised again during a time of political stress both within the country and around the world.

Hogwash!  That dam is as safe or safer than any dam in the modern world.

The article posted doesn't mention collapse at all. I'm sure it's designed so the spillway will allow the excess rainfall to proceed downstream. I think this is another example of an editor misnaming an article for click bait reasons. 

Edited June 25, 2020 by Ward Smith

[Enthalpic + 1,496]

Obviously you would just let the water go (even if it floods areas downstream) before letting the dam collapse.

[Ward Smith + 6,615]

Looks like the problem is with Google Images.

[ronwagn + 6,290]

All I know is the article and the comments. I certainly hope it doesn't fail. The Tennessee Valley Authority fought the same battles but within the country, not damaging other nations interests. 

Our Oroville Dam, near Sacramento, has had major problems and it was supposedly well engineered, as was the Titanic. The U.S.A. has hundreds of dams that are at risk of failing. Most have probably never been dredged either. 

[Marcin2 + 726]

36 minutes ago, ronwagn said:

All I know is the article and the comments. I certainly hope it doesn't fail. The Tennessee Valley Authority fought the same battles but within the country, not damaging other nations interests. 

Our Oroville Dam, near Sacramento, has had major problems and it was supposedly well engineered, as was the Titanic. The U.S.A. has hundreds of dams that are at risk of failing. Most have probably never been dredged either. 

Ron, Society of American Civil Engineers graded US Dams : D

in their infrastructure report card of 2017.

Their is lack of maintenance , dams are not repaired.

Theire is imminent danger that ( unlike in China) some of them would collapse.

Look, China built dams on Yangtze: one the largest rivers ever dammed, larger than Mississippi. They are super safe as Dan stated.

[Marcin2 + 726]

10 hours ago, Dan Warnick said:

Hogwash! 

I have stood at the base of that dam, on both sides of it.  I have been inside the power turbine tunnels.  I have walked in the overflow channels, driven/walked in the ship elevator, log and debris release, sludge abatement areas, and on top of it.  I did all of that during its construction and my host was the CEO of an Chinese/Italian/German/American/British consortium that had over 700 expat families living and working on site for the duration of its construction.  The designs were the result of many great minds from around the world coming together.

All of the "threats" that are being trumpeted now are exactly what the dam was designed and built to not only withstand, but far exceed.  It is not lost on me that mixed among the rhetoric about the dangers of the flooding right now are the mentions and reminders of the "great ecological damage"  and "human displacement" the dam was responsible for when it was constructed.  I have to ask myself why these complaints would be raised again during a time of political stress both within the country and around the world.

Hogwash!  That dam is as safe or safer than any dam in the modern world.

I am really jealous that you had an Opportunity to visit 22.5 GW power plant. The largest I was touring as part of my job was only 5 GW.

[Coffeeguyzz + 454]

As of this posting - late evening, Thursday the 25th - the weather forecast is calling for non stop rain over the next 9 to 12 days (commencing tomorrow evening) totalling 250+mm (10+ inches).

The videos coming out of China showing the raging flooding/mudslides are simply astonishing.

As is to be expected in these crazy times, hyper political input seems to be  rearing its familiar head.

Setting aside the 3GD status for the moment, it is becoming clear that a large, destructive event is imminent due to the massive flooding already underway.

[Eyes Wide Open + 3,555]

41 minutes ago, Coffeeguyzz said:

As of this posting - late evening, Thursday the 25th - the weather forecast is calling for non stop rain over the next 9 to 12 days (commencing tomorrow evening) totalling 250+mm (10+ inches).

The videos coming out of China showing the raging flooding/mudslides are simply astonishing.

As is to be expected in these crazy times, hyper political input seems to be  rearing its familiar head.

Setting aside the 3GD status for the moment, it is becoming clear that a large, destructive event is imminent due to the massive flooding already underway.

One must admit we live in a world of extreme casualty. On one had China is facing a watershed event amd at the same time the US is about to expect a desert spawned dust storm from 4000 miles away.

 

 

[Marcin2 + 726]

I think conspiracy theorists at this thread need to understand how flood control works.

There are many dams, huge dams on Yangtze and tributaries, each with large flood capacity. Three Gorges has 22 km3 of flood capacity.

When there are large rains in upper Yangtze and the flood is expected, the water level in the dam goes down from 165-170 to 140 meters. And when large flood wave hits, the dams can decrease this wave ( as a system of many). For example at major floods it keeps up to 40,000 m3 per second, inflow could be 110,000 m3 catastrophic for downstream China, but outflow is kept at a safe 70,000.

40,000 m3 per second kept in the dam is like 2.5 Mississipi average flows, just that you know the scale.

And dam can withstand such a wave for a few days ( it never happened but dam is built for one in 10,000 years flood plus 10%)

[SUZNV + 1,197]

I don't actively go to the epoch time for sources simply because it is advocate as if Ancient China culture was the center of the world  and has great traditional values, god (not Christian god) vs  CCP. From my point any country in the  past have its glory time and hell time, greatest and worst values and don't like the idea of God chose China (I think its copy from Jews are chosen people), Boost one ego to go against another. But as the freedom of speech, it keeps on remind people events CCP wants to erase or rewrite. Most of Western media tried to avoid these issues.

I don't think it is the emergency matter because of  the flood/earthquake or image from the satellite. I see nothing bad with the number in the water level.This year has too many thing with the Covid19, AntifFA, North Korea, FBI unmasked, Oil War  etc and everything seems targeting on the US election this year.

But the accumulated mud overtime and the deform after 40 years from now will make it a big technology debt. The geo formation was shaped by the same flow for that last thousands years. Then Geologists analyzed it and based on that to construct reinforcement base on that data but the flow changed. The river is a living thing, not like the great wall.

Mao didn't want to build it. He said something about can you sleep with a water bucket on your head. Deng and Lee and Jiang advocated for it yet if I recall correctly, no high ranking officials (no Lee no Jiang)  attended  the celebration when it finished.

When I was in uni around 2007 in NZ, I mentioned its Capacity in an essay and the tutor who interviewed me seemed didn't believe in its size and keep asking me "are you sure" or suggested me to  drop some 0s without even bothered to check it himself.  It is an compulsory Engineer course about risk, responsibility, professional development.  One of the video in one lecture were about the sea level claimed NY  in 2018 from CNN.

It is not about China or CCP. We know anything has its age. Off course  there are people want it to collapse and count that is a crime/stupidity /arrogance of CCP but I wouldn't trade a disaster for a CCP collapsing. But the dam with no disaster still has pros and cons. The pros sides were emphasized for investment and political decision, the cons sides , besides risk of a disaster, was never fully explored as each river has its own characteristics.  

There is flooding season in South Vietnam. When I was young I keep wondering why people kept living there if they know there will be floods. Later on I learned that a long with the flood is the fertilization from the sediments. No flood and you will have to put more chemical fertilizer ---> more chemical productions ---> more pollution. 

The clear  river in Mekong in Thailand is very less nutrition:

https://www.nytimes.com/2020/02/15/world/asia/mekong-river-dams-thailand.html#:~:text=NONG KHAI%2C Thailand — The water,beautiful but it means death. 

Secondly the 2 purposes of the dam conflicts to each other. Regulate floods and make electricity. In the drying season, the damn have to release its water for agriculture and because of that, less electricity is generated and need some other sources to meet the electrical demand while in the flood season it will be the reverse. The downstream will say we have too much water already while the upper stream will say we cannot stop, we need to make electricity. Kind of the classical  renewable resources' problem : a back up power source.

In the United States roughly 900 dams were removed between 1990 and 2015, with another 50 to 60 more every year. I read somewhere it was the same trend in West and  Northern Europe while many developing countries keep building theses. 

I would say this and deforestation and chemical & waste pollution on rivers and seas  is bigger issue than the sea level rise or CO2. Less water down the river will have consequence in the sea salt invasion and reduce the agriculture land which has been effected much because of the urbanization and real estate bubbles.  In Vietnam, the government don't worry much because it gave them a chance for pocketing aids + charity and become the evidence of the sea level rising with salty invasion farm land. It seems a win win situation for every politician all over the world but nature and the most affected people were ignored. No initiative to solve the problem at all. I doubt these costs were calculated in the building planning.

I don't like massive dams, I think it should be splited to many many small dams for the flexible controls. Just like in IT from big server to services and micro services and to  serverless. The bigger the dams, the more flavor to nuclear power plants, the same level of safety in design and if take the disaster out of the equation, nuclear have much less consequences and unexpected side effects. 

Edited June 26, 2020 by SUZNV

[ricardo2000 + 1]

I don't believe this dam will collapse, but as the responsible authorities at the dam said, 'Flood storage capabilities are limited.' Meaning the dam is reaching capacity and might have to allow a storm surge of up to 10 metres to be released.

[footeab@yahoo.com + 2,194]

On 6/24/2020 at 10:01 PM, ronwagn said:

 

On 6/24/2020 at 10:01 PM, ronwagn said:

 

 

I'm disappointed.  Normally you do not post sensationalist Bull Shit...  Obviously the photo is doctored or manipulated.  If any part of any dam moved that much the entire thing would have blown wide open.  Concrete shatters, it does not bend. 

[ronwagn + 6,290]

On 6/25/2020 at 12:56 AM, Marcin2 said:

@ronwagn Could you Please insert the whole article. The site requires sign up to read it.

China’s Largest Dam Draws Scrutiny for Structural Flaws as Flooding Ravages Country

BY EVA FU

 

June 24, 2020 Updated: June 26, 2020

 

 

Print

✉

China’s controversial Three Gorges Dam, the largest hydropower project in the world, has drawn scrutiny for its structural flaws and environmental damage ever since its construction was first proposed in the 1950s.

As torrential rainstorms are currently sweeping through half of China, a hydrology expert warns that the dam could collapse under the added pressure, endangering the lives of millions who reside nearby.

Widespread flooding has affected at least 11.2 million people in 26 Chinese provinces and municipalities across central and southern China since heavy rainfall began wreaking havoc in early June. More than 9,300 houses have tumbled and 171,000 others have sustained damage. The financial damage has surpassed 24.1 billion yuan ($3.4 billion), according to local authorities.

The record rainfall is forecasted to continue for another 10 days.

In Guizhou, a mountainous province in China’s southwest, the stormwater at one point rose to 16 feet higher than acceptable thresholds.

The flooding in Yanhe County caused water to cascade over a bridge and wash away houses underneath.

“It’s a hotpot in water,” Mr. Liu, a resident of Qijiang County, in the southwestern city of Chongqing, said in an interview. The flooding, he said, is “sounding a warning to the rest of China.” If the nearby Three Gorges Dam cannot withstand the water right now, the lower reaches of the Yangtze River, one of the country’s most fertile and populous regions, would be in serious trouble, he predicted.

‘Pressed From Both Ends’

Built with the stated objective of taming the flood-prone Yangtze River and generating clean energy, the massive 180 billion yuan ($25.4 billion) project has been plagued by corruption and environmental costs. Authorities’ forced relocation of over 1 million residents further fueled public anger.

A worker collects floating rubbish at Three Gorges Reservoir Region in Chongqing, China, on July 22, 2018. (Getty Images)

“Whether the Three Gorges can play a role in preventing flooding in the current situation, or if the Chinese government has deceived the Chinese public from the beginning—this has been made pretty clear for people throughout the years,” Wang Weiluo, a Chinese hydrologist who is currently residing in Germany, told The Epoch Times.

The Yangtze River runs through 11 Chinese provinces and regions in central and western China, including Tibet, Sichuan, Chongqing, Hubei, and Shanghai. Many regions have a water level below that in the dam’s reservoir, placing them “directly under the water currents” during times of flooding, Wang said.

Authorities have for years hushed voices critical of the dam.

Reached by The Epoch Times on June 23 about the Three Gorges, Fan Xiao, a senior engineer in the state-owned Sichuan Bureau of Geological Exploration and Exploitation of Mineral Resources, said his superiors had instructed him earlier in the day “not to take any foreign media interviews.”

Fan did, however, write extensively about issues surrounding the Three Gorges Dam. One article in 2004, for example, explored the issue of reservoir-induced earthquakes and landslides. Another, in 2016, questioned the dam’s “net capacity” in flood mitigation, after accounting for the cost of destroying local habitats.

There’s also a fundamental conflict between people in the upper reaches and the lower reaches, Wang said. When there’s heavy rain, the former wants the water discharged, while the latter cannot deal with the additional flooding.

“The Three Gorges is pressed from both ends,” he said. Currently, the reservoir has kept a water level lower than normal to ensure the dam’s safety.

In a picture taken on June 16, 2011, a resident looks out at the site where last October, a huge chunk of hillside broke free in Badong, in Hubei province, on the Yangtze River. (Peter Parks/AFP via Getty Images)

Systemic Issues

A glance at Chinese media reports over the years conveys a diminishing sense of confidence in the dam.

In 2003, an article headline from state media Xinhua said the dam could withstand a once-in-a-10,000-year flood; the wording was changed to 1,000 years in 2007, then 100 years in 2008; and in 2010, a TV anchor at state broadcaster CCTV cited the Changjiang Water Resources Commission, which has direct oversight over the Yangtze River Basin, saying that people “cannot place all their hopes on the Three Gorges Dam.”

The structural integrity of the dam itself triggered widespread debate last year after a satellite image of the dam purportedly showed a curvature, raising fears that it may break.

While the operating company of the Three Gorges dam has dismissed the concerns by pointing to potential inaccuracies with Google satellite images, it later admitted in a social media post that the dam had moved by up to 1.05 inches. The company said it was within acceptable margins.

Authorities said they are discharging floodwater at around 980 water reservoirs along the Yangtze River, while they have hesitated to release the water inside the Three Gorges Dam, despite the level reaching a two-meter excess (6.6 feet)—citing concerns about sudden flooding. But netizens recently circulated a video accusing authorities of secretly discharging the dam water without giving advance notice, worsening their plight.

Wang is urging people living near the dam to prepare emergency kits to protect themselves. “The Chinese Communist Party will never take responsibility for it … Every death is just a number” to the regime, he said.

Mr. Chen, a resident of Sichuan Province, worries that something more catastrophic could befall China in the future under the regime’s mismanagement.

“The government made this [dam] a show project,” he told The Epoch Times’ sister media NTD. “After the disastrous consequences, commoners always foot the bill.”

Follow Eva on Twitter: @EvaSailEast

[ronwagn + 6,290]

https://vietreader.com/world/2438-massive-flooding-in-south-china-three-gorges-sanxia-dam-at-risk-of-collapse-any-time.html

http://www.globaltimes.cn/content/1192443.shtml Says no problem.

https://agrdailynews.com/2020/06/25/flood-alert-at-three-gorges-dam-asia-times/

Edited June 26, 2020 by ronwagn
added reference

[Strangelovesurfing + 737]

Looking at google earth there seems to be some warping but nothing near the split picture shown up top here. I hope that dam holds, a lot of ordinary people will pay the price if not.

One big issue, what happens if an earthquake hits while so much water is being dealt with?

Scary stuff.

Edited June 27, 2020 by Strangelovesurfing

[ronwagn + 6,290]

For now it seems that the real concerns are more about other dams and the flooding. There is potential danger from earthquakes and if flooding becomes common. Millions of downstream people are concerned. 

[Dan Warnick + 6,100]

On 6/26/2020 at 10:58 AM, ronwagn said:

All I know is the article and the comments. I certainly hope it doesn't fail. The Tennessee Valley Authority fought the same battles but within the country, not damaging other nations interests. 

Our Oroville Dam, near Sacramento, has had major problems and it was supposedly well engineered, as was the Titanic. The U.S.A. has hundreds of dams that are at risk of failing. Most have probably never been dredged either. 

The article leaves out sooo many details about what this dam was built for, and what it can sustain.  Such as the fact that it was constructed to replace a number of dams built over centuries that were too old and at risk of failing, and currently ineffective at doing an acceptable job.  That the dam's main, number 1, overriding reason for being built was to alleviate annual flooding downstream that consistently wiped out agriculture, property, and human and animal life.  2nd, although very important, was/is power generation.  The reason for the power generation is obvious in their expanding society and development, but the 1st reason not as much.  The 1st reason, to stop annual flooding, was/is to break the chain of flooding which inhibited agriculture downstream to contribute to and sustain the population with food and other agricultural products consistently.  "Downstream" of the 3 Gorges is a huge landmass that floods almost every year.  There is obvious financial impact to those losses but more importantly China simply cannot afford to have any kinks in its production of food, and this was a big one.

The 3 Gorges is designed with all of the world's old dam's problems and shortcomings in mind.  There was a quote in the article that was telling: In Chongqing, authorities dredged 100,000 tonnes of silt overnight as levels rose.

The reason I say it is telling is because it sounds like it was some sort of emergency response.  It was not.  The dam has silt dredging built into it. One of those things learned and technologies designed to control and alleviate.  If you think about it, silt is not only dangerous to the dam's structure, but it can compromise other working sections of the dam as well.  This dam and at least one other major dam they have built have this silt removal technology built in.

[Dan Warnick + 6,100]

On 6/26/2020 at 12:00 PM, Coffeeguyzz said:

As of this posting - late evening, Thursday the 25th - the weather forecast is calling for non stop rain over the next 9 to 12 days (commencing tomorrow evening) totalling 250+mm (10+ inches).

The videos coming out of China showing the raging flooding/mudslides are simply astonishing.

As is to be expected in these crazy times, hyper political input seems to be  rearing its familiar head.

Setting aside the 3GD status for the moment, it is becoming clear that a large, destructive event is imminent due to the massive flooding already underway.

In bold, above.  There are some impressive videos, but most of them show areas of China that are very far away from the 3 gorges.  I mean, they don't show any flooding at the dam; the dam is simply showing higher levels. 

And as far as mudslides, they are a problem and have been a problem ever since Mao caused the defoliation of most of the country, not to mention the hillsides and mountains, by giving orders to melt all metal in China to falsely show that steel production in China was more than England.  In order to accomplish this idiotic goal, fires to melt every piece of cutlery, belt buckle and every other item made of metal were kept lit and going all over the country, 24/7.  Fuel for the fires?  Trees from every surface not already cultivated for agriculture.  China has aggressively planted trees over the past years, but in many areas trees with substantial root systems don't have enough soil to claw into and hold, so you get a lot of trees with shallow root systems that are themselves easy to wash away.