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China’s evaporating wetlands

Ponds and marshes are drying up around the country. Land is reclaimed for agriculture and industry, while reservoirs and dams disrupt the flow of rivers. The wetlands are in trouble, writes Jiang Gaoming.

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News came from my hometown earlier this year: the local government had decided to spend 50,000 yuan (about US$7,300) sinking new wells to combat shortages of water for irrigation. The site used to be wetland; back in the 1960s, people used to grow rice there. But when the drilling team started work in April they sank a 200-metre-deep shaft and found no sign of water. In May they were forced to give up.

How was it possible that no water could be found under a former wetland? The locals were astonished. The story started back in the 1980s, when land reforms encouraged farmers to raise their own crops, causing a shortage of land. Wetlands were reclaimed and trenches dug to drain water away; springs were blocked with sand and covered with soil. The wetlands dried out to make way for more arable land. Surrounding villages followed suit; ponds and waterways were covered over and riverside vegetation cut back. Even centuries-old graveyards were used to raise crops. In rural areas, anywhere that once held water was flattened; in and around the towns, they were tarred or concreted over. Farmland increased, but the wetlands were lost and the weather got drier. Now you cannot find a drop of groundwater.

The national situation is even more worrying. The northern province of Hebei lost 90% of its wetlands in the last 50 years; 80% of what is left is polluted. In Shaanxi province the 30 counties in the Guanzhong area have seen up to 10,000 ponds disappear. Poyang Lake, China's largest freshwater lake, now shrinks to as small as 50 square kilometers, down from 4,000 at its peak. The loss of wetlands has meant aridity spreading from the north to the country’s fertile south. In 2007, tens of millions of people living around Poyang Lake suffered drinking water shortages. Wetlands in arid and semi-arid regions are not faring any better. Alashan, in Inner Mongolia, is seeing wetlands dry up due to water abstraction from the Hei River upstream. Water flowing into this traditionally green area has dropped from 900 million cubic metres to 200 million, leading to the disappearance of hundreds of lakes and ponds. The creation of new farmland around the upper reaches of the Tarim River, in Xinjiang autonomous region, has lead to a 350 kilometre-stretch of the river drying up, with deserts appearing where lakes once were.

Many are quick to blame the loss of wetlands on climate change. Global factors and a lack of precipitation do, to a certain extent, present a threat to wetlands, particularly in areas which are already arid or semi-arid. However, we cannot ignore human activity in rural areas. In most areas the loss of wetlands is not a natural disaster, but a manmade problem.

First, the reclamation of land from lakes, rivers and the sea has directly replaced wetlands with dry land. Land shortages mean that in rural areas any type of wetland – ponds, marshes, the banks of lakes – have been targets for appropriation. During the Great Leap Forward in 1958, a large number of farmers in Hunan province were moved into the Dongting Lake region to reclaim the land, with dykes used to push back the waters of lakes, shrinking it to a fraction of its former size. Hubei, known as the province of a thousand lakes, has gradually transformed its lakes into farmland. What remains is inadequate to mitigate the effects of flooding and drought. The area affected by flooding and drought consequently grew from 460,000 hectares in the 1950s to 1.7 million hectares in the ‘80s. Land shortages are even more severe in coastal areas; the enthusiasm for creating new land remains in Shanghai, Xiamen and other cities. The city of Xiancheng, in Jiangsu province, used to have 582 kilometres of coastal wetlands; now it has only a 50-kilometre “core area” as a habitat for the red-crowned crane and other wildlife. Areas that were once wide expanses of coastal wetlands have been replaced with factories, paper mills, farms and salt pans. Some polluting industries that are no longer welcome in southern China, including chemical plants, printing, dyeing and paper-making factories, have relocated here and represent a potentially fatal threat to the local environment.

Second, reservoirs are cutting off rivers, which means wetlands downstream are shrinking or disappearing entirely. China has more reservoirs than any other nation, with almost 86,000 at the end of 2006. Once a reservoir has been built the downstream areas will only receive water that is not wanted further upstream. The wetlands, which rely on this water, are then at risk. The threat is particular grave to wetlands in arid and semi-arid regions. Ten reservoirs have been built on the 8 tributaries of the Heyang River, in Gansu province, leaving downstream Minqin county severely short of water. It may even meet the same fate as Lop Nur and dry up completely.

Third, the construction of large dams is exacerbating the disappearance of wetlands. There are 22,000 large dams in China; 45% of the world’s total and more than in any other country. The debate continues over the effect of these dams on the environment, but nobody denies that the disruption of water flow causes the loss of wetlands. When the Xiaolangdi reservoir, in Henan province, went into operation on the Yellow River, water levels fell downstream and wetland areas decreased, clearly seen in both shallows and wetlands upstream from Kaifeng. Remote sensing data puts the area of wetlands in the lower reaches of the Yellow River at 724.3 square kilometres in 1997, decreasing to 651.6 square kilometers by 2003. The Three Gorges dam also caused river water levels to drop and drew water out of lakes. In summer 2006 some areas on the upper reaches of the Yangtze River saw the worst droughts since 1949.

Over-extraction of groundwater also causes the loss of wetlands. Aridity, upstream reservoirs and pollution meant that surface water proved inadequate for needs of the public, so they turned to the groundwater hundreds or thousands of metres under their feet. Over-extraction of groundwater in the Hai River basin affects an area of 90,000 square kilometers: 70% of the total area of the plains. At one time, 40% of Tianjin's land area was wetland, now this has decreased to 7%. Lake Baiyangdian, known as the “pearl of the north”, has dried up on seven occasions since the 1960s, once for five years. Extracting groundwater also causes subsidence, with ground levels dropping by up to three metres in parts of Tianjin. One area of eight square kilometres now lies below sea level.

Pollution is also destroying China’s wetlands. Wetlands can clean up a certain amount of pollution, but there are limits beyond which they are at risk of destruction. All of China's seven major river systems – the Liao River, Hai River, Huai River, Yellow River, Songhua River, Pearl River and Yangtze River – are severely polluted. The Xiaoqing River in Shandong was once famous for the clarity of its waters, but they now run closer to black. There are 110 waste-water outlets flowing into this river in Jinan city alone, with eight large factories pumping out industrial effluent. Avoiding responsibility for its own pollution, one well known paper manufacturer 50 kilometres away is unloading its waste into the river.

Wetlands are sometimes called the kidneys of the world. Losing them means losing their ability to regulate the climate, absorb floodwaters and clean up pollution; it may worsen droughts and floods and mean the loss of natural habitats for wildlife. We should waste no time in saving China’s wetlands.


Jiang Gaoming is a professor and Ph.D. tutor at the Chinese Academy of Sciences’ Institute of Botany. He is also vice secretary-general of the UNESCO China-MAB (Man and the Biosphere) Committee and a member of the UNESCO MAB Urban Group. He is known for his concepts of “urban vegetation” and allowing damaged ecosystems to recover naturally.

Homepage photo by mke1963

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评论通过管理员审核后翻译成中文或英文。 最大字符 1200。

Comments are translated into either Chinese or English after being moderated. Maximum characters 1200.

评论 comments

Default avatar
匿名 | Anonymous



An empty talk

It is a bare fact that we are losing the wetlands, many people have already realized this problem. Now the important thing is how to protect them during the survival and developemt of the mankind. To develop all kinds of industries is the main path to improve the economy of provinces, counties and cities. If we don't have the power of economy, protecting the wetlands is just an empty talk. May I ask what do you think of this, Mr. Jiang?

This comment was translated by Lijin Zeng

Default avatar
匿名 | Anonymous




The comment on Lake Poyang is misleading. Poyang Lake’s water levels naturally rise and fall every year. They are not steady at all. It is a mistake to say that the lake shrank from 1400 sq km to 50 sq km; it is unscientific. The lake has passed the period when its surface area is 1400 sq km. Now it is time for the dry period, when it is 50 sq km. diovedo

(Comment translated by Michelle Deeter)

Default avatar
匿名 | Anonymous



本评论由tom tang翻译

Regarding comment 2

I agree that the comment is misleading, because the Poyang Lake’s water levels are supposed to rise and fall, and that is not mentioned in the article.

Still, despite these flaws, the article has merit. We need to worry about Lake Poyang because the lake levels are lower than normal. Tan Guoliang, director of the Hydrological Bureau in the Jiangxi Province, reported that the water surface was 300 to 500 square kilometers last winter. (see http://tinyurl.com/6pq2bo) Therefore, it would be silly to expect the lake to be 4000 sq km in winter. But 50 sq km is still too small.

Default avatar
匿名 | Anonymous



The Depth of Poyang Lake

Thanks for reminding me of the questions above. And according to the status of environment department website(English Version), waterline of rainless period is 300-500 sq.km. However, evaporating wetlands of Poyang Lake is still a problem. Jiang Gaoming

This comment was translated by Stacy Xu.

Default avatar
匿名 | Anonymous




Opposite Opinion

I didn't deny the crisis of vanishing wetlands in China. However, in this article, it is quite misleading that the way the author described Poyang Lake. This example, to some extent, is unproper and ulterior-motived so that the effect is remarkable.(The figure 4000-50,everyone is shocked!) In fact, the problem in such a small water area cannot be regarded as a crisis mentioned by the author, not even a problem at all. In 2006, this situation is caused by the less current from upper reaches of Changjiang River. Poyang Lake supplied numerously to Changjiang River and its waterline declined rapidly; while in 1998, it was the opposite situation. Because of the abundent current from upper reaches of Changjiang River, Poyang Lake received a lot of water so that its water area had increased by 5000 sq.km. Using such unproper emample first would devaluate the article. Also the author's knowledge of specific field would be questioned. Take one example of the article, the joke of name Chao Lake of Zhujiang River, I believe that no one would like to read it in an environmental article.

This comment was translated by Stacy Xu.

Default avatar
匿名 | Anonymous



Continuing the discussion

The shrinking of Poyang Lake is the truth. However,the main reason (or you can say,the whole reason) is to do with the water level of the upper reaches of Yangtze River. How much water comes from the upper reaches? We cannot only attribute that to human activities. I don't quite understand the connection between the contribution of the Three Gorges dam and the drop of river water levels, which is suggested by Mr. Jiang in this article.

Firstly, that would only happen when the reservoir is about to store water. As soon as the water in the reservior reaches the required level, normally,the water level will be the same for the upper and lower reaches.In that case, a drop in water level won't happen. Secondly,the capacity of the reservoir should not be a big issue in comparison with the volume of water coming down from the upper reaches.

I also question Mr.Jiang's description of the Xiaolangdi reservoir. The purpose of its contribution is to improve water and soil condition. As is known, the sediment problem of Yellow River is quite severe. It is threatening the river and residents' life and production. The beautiful wetland mentioned by Mr.Jiang will turn to hell for people living along Yellow River when it floods.

This comment was translated by Si Meng

Default avatar
匿名 | Anonymous



Response to Comment 5

Comment 5 is truly funny, why was there less water flowing from the upper reaches in 2006? You must know, because precipitation in the Yangtze River basin is very low in winter, the water reservoirs in the Yangtze's upper reaches only store water for generating electricity, there is no output. I am not sure that the reservoir of the upper reaches of the Yangtze Rivera main is a main reason for the drop in the water level of the Poyang Lake, but at least it is one of the reasons. (Translated by David Vance Wagner)