ACADEMIC

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An Assessment of the Economic Losses Resulting from Wetland Disturbance and Destruction in China

by Ning Datong

Wetlands in China

Size and Distribution of Chinese Wetlands

Wetlands include marshes, swamps, salt marshes, parts of streams, shorelines, and flood plains.1 At present, wetlands in China cover over 25 Mha, representing 2.6 percent of the country’s entire area. The wetlands of China consist of marshes (11 Mha); natural and artificial lakes (12 Mha); shoals (12 Mha); and salt marshes (2.1 Mha). Approximately 80 percent of the wetlands in China (20 Mha) are of the fresh water variety.2

Distribution of China’s wetlands is as follows:

1) North-east China:
a) Possesses the most extensive freshwater marshes in the country, with the Sanjiang Plain alone accounting for 1.12 Mha of freshwater marshland.
2) North-central China:
a) Along the southern edge of the Gobi desert, this region includes several large saltwater lakes and salt marshes.
3) East China:
a) Along the middle and lower reaches of Yellow and Yangzi River basins, this region includes a number of fairly large wetlands, and China’s largest concentration of large freshwater lakes.
b) Starting from Hangzhou bay in Zhejiang province and moving northward along the coast, this sandy and muddy region (other than a few rocky areas on the Shandong peninsula) constitutes the majority of China’s 2.1 Mha of coastal marsh-land and shoals.
c) The coastline starting at Hangzhou bay in Zhejiang province extending southward, is rocky for the most part, with the exception of a few wetlands at river mouths and along deltas such as the Zhujiang delta in Guangdong province and the Minjiang delta in Fujian province.
4) South China:
a) A number of wetlands are dispersed throughout the provinces of Yunnan, Guizhou and Sichuan.
5) North-west China:
a) The desert regions of Xinjiang province include a number of large saltwater lakes and salt water marshes.
b) The remote north-west Tian and Alti mountain ranges contain some large freshwater lakes and wetlands.
6) West China:
a) Along the Qinghai-Tibetan Plateau countless lakes and marshes are dispersed.

Basic Characteristics of Chinese Wetlands

Lakes and marshes constitute the majority of Chinese wetlands. Of China’s 217 recognized wetlands, 95 have been declared nature reserves. Despite such efforts to protect wetlands, it is estimated that 40 percent of China’s important wetlands have been disturbed by human activities and face moderate to serious threats of deterioration. These threats take the form of lake pollution, excessive fishing and hunting, and conversion of wetlands into farmland.

The Impact of Development on Chinese Wetlands

Actions by both humans and nature affect China’s wetlands. Natural influences are generally limited to climactic changes, whereas human influences are artificial, and include such activities as land reclamation for cultivation purposes and dam construction. As a result of such human activities, China’s wetlands have been shrinking steadily. In the early 1950s, there were 24,880 natural lakes of various dimensions in China, with a total area of 83,000 km2.3 Over the past thirty years, lake area in the entire country has decreased by more than 12,000 km2.

Exemplifying the decline of wetland area is the changing status of lakes over 1 km2. In the 1950s, China had 2,848 such lakes, with an aggregate area of 80,645 km2. By the beginning of the 1980s, the number of lakes over 1 km2 had decreased to only 2,305, with an aggregate area of 70,988 km2.4 We estimate that 543 lakes over 1 km2 in size either contracted or completely disappeared throughout the entire country in the last thirty years. Table 1 presents statistical data on the reduction of lake-area in China.5

Table 1: Reduction of Lake Area Per-Lake Group from the 1950s to the 1980s (km2)
Lake Group Lake Area
Early 1950s		 Lake Area
Early 1980s		 Reduction
in Area		 Reduction
in Area (%)
Qinghai-Xizang
Plateau		 38,700 36,889 1,811 4.7
Eastern Plain 22,900 20,842 2,058 0.004
Mongolia-Xinjiang
Plateau		 16,400 9,411 6,989 42.6
Plain-Mountainous
Region of
Northeastern China		 3,800 2,366 1,434 37.7
Yunnan-Guizhou
Plateau		 1,200 1,108 92 7.7
Total 83,000 70,616 12,384 14.9

According to this Table, from the 1950s to the 1980s, the total area of natural lakes in China decreased by 12,384 km2. The Mongolia-Xinjiang Plateau and the Eastern plains are the sites of the largest decreases in lake area. The smallest decreases in lake area occurred on the Yunnan-Guizhou Plateau. Exemplifying the decrease of lake area are Poyang lake, where area decreased by 3.21 Mha, and Dongting lake, where area decreased by 160,000 ha6 An additional example is Taihu lake which decreased in size by about 160,000 ha between 1969 and 1974.7 Finally, between the 1950s and the 1980s, the number of lakes over 50 ha on the Jiangshan Plain declined by 49.36 percent, with total lake area decreasing by 43.67 percent.8

Table 2: Analysis of Economic Gains and Losses Arising from Altered Wetlands in China
Main Contents Cost (-) and Benefit (+)
Conversion to Farmland a) Grain output +
b) The decline of flood control ability –
c) The loss of fishery yields –
d) The loss of deposition –
Silt Deposition in Lakes and Reservoirs a) The decline of irrigation ability –
b) The decline of flood control ability –
Drainage to Create Farmland a) Reducing disease +
b) Destruction of habitat –
c) Destruction of mangrove forests –
Other Respects a) Unsuitable hunting and fishing –

Conversion of Lakes and Marshes into Agricultural Land

The soil along the edge of lakes is deep, and rich in the nutrients (e.g., nitrogen, phosphorous, potassium) essential to high-yield agricultural production. According to studies conducted in the Poyang Lake region, newly converted lake-shore land produces high yields for up to three years without the introduction of organic or chemical fertilizers. In the Dongting lake region, water conservation works undertaken since the 1950s have resulted in the expansion of farmland from 400,000 ha to 580,000 ha. As a result, agricultural yields in this region reached 3.25 billion kg in 1974, one fifth of the total output for the entire province. The land required to achieve this output was only one fifth of the total farmland in the province.9

In addition to creating additional farmland, draining marshes contributes to a reduction of disease. However, large scale lake-shore and marshland conversion for cultivation purposes has also caused a rapid reduction of both the area and the number of lakes and marshes. For example, over the past 30 years, Dongting Lake has decreased in size from 4,350 km2 to 2,740 km2, a rate of approximately 50 km2 per year.10

Furthermore, approximately 1,000 lakes of various sizes, along the middle and lower reaches of Yangzi River have vanished as a result of conversion for cultivation purposes. Since 1954, water storage capacity in this region has declined by about 12,000 km2. Assuming that 1.5 meters is the average depth of coastal waters, we deduce that 18 billion m3 of fresh water resources have been lost, the equivalent of one half of the annual flow of the Huai River.11

Silt Deposition in Rivers, Lakes and Reservoirs

Between 1951 and 1978, the annual average deposition of silt in Dongting Lake was 101.7 million m3. Assuming that the area of Dongting Lake is approximately 2,740 km2, silt deposits raised the lake-bed by approximately 3.7 cm each year.12

The annual silt load of the Yangzi River, as measured at Hukuo station, is 10.522 million tons.13 Silt deposits along the length of the Yangzi River, its tributaries and lakes, have contributed to a decrease in the absolute number and length of navigable waterways.

Notes to Summary:

  1. Ma Xuegin, et al. (eds.), Marsh swamp of China (Science Press, 1991). Also see: Li Rongao et al., Assessment and Management of Land Resources (China Environmental Sciences Press, 1993).
  2. Lu Jianjian (ed.), Chinese Wetlands (East China Normal University Press, 1990).
  3. Jin Xiangcan, et al., Lake Eutrophication in China (China Environmental Sciences Press, 1990).
  4. Ibid.
  5. Ibid.
  6. Compilatory Board of Poyang Lake Study, Poyang Lake study (Shanghai Science and Technology Press, 1988). Also see Gu Dinxi, “Prevention and Exploitation of Lakes,” Collected Works on China’s Nature Conservation (China Environmental Sciences Press, 1990).
  7. Compilatory Board of Poyang Lake Study, Poyang Lake study.
  8. Hu Angang, and Wang Yi, Survival and Development (Science Press, 1989). Also see Compilatory Board of Essentials of China Natural Conservation, Essentials of China nature Conservation (China Environmental Sciences Press, 1987).
  9. Institute of Geography and Limnology (ed.), An introduction to China’s Lakes (Science Press, 1989).
  10. Gu Dinxi, Collected Works on China’s Nature Conservation.
  11. Institute of Geography and Limnology (ed.), An introduction to China’s Lakes.
  12. Zhang Kaiming, “Present Situation and Conservation Efforts of Aquatic Resource for China’s Fresh Water,” Collected Works on China’s Nature Conservation (China Environmental Sciences Press, 1990). Also see Jin Xiangcan et al., Lake Eutrophication in Chin., and Li Rongao et al., Assessment and Management of Land Resources.
  13. Compilatory Board of Poyang Lake Study, Poyang Lake study.

Project on Environmental Scarcities, State Capacity, & Civil Violence