The Three Gorges Project. Part X:
Ecological & Environmental Concerns.
(3) TGP will significantly affect the fish species in the upper and middle
reaches of the Yangtze River.
The fish resources of the Yangtze River are quite abundant. There are
196 fish species in the upper reach, among which 90 belong to special
species . The effects of TGP to the fishery in the upper reach of the river
are mixed. Because TGP will significantly reduce the flow speed and
aggravate siltation in the reservoir, it will change the natural habitat (e.g.,
the food composition) of these fish species. A number of special species may
not be able to adapt to the new environment and may suffer a dramatic reduction
in numbers. It is estimated that TGP will reduce the habitat area of more than
10 special species by 20-25%. However, the amount of native fishes is
expected to increase in the reservoir.
TGP will seriously affect the fish species in the middle reach of the
Yangtze River, which is a major breeding area for the four Chinese native
fishes. During flood season, the breeding of these native species requires a
certain rise of the water level as well as the water temperature to be above
18 degrees (in Celsius). Because TGP will dramatically reduce the downstream
water temperature and the rise of water level during flood season, it will delay
the breeding period of these species by 7 (for the 150-meter scheme) to 20 (for
the 180-meter scheme) days. Some species may even disappear. The dam
will also keep most of the fry bred in the upper reach from flowing
downstream, and seriously affect the fishery of Hubei and Hunan provinces.
It is estimated that TGP will reduce 3.5 billion fry catches in these areas.
Last but certainly not least, TGP may speed up the extinction of the
rare species, such as Chinese sturgeon (Zhong1 Hua2 Xun3) and Chinese
paddlefish (Bai3 Ji4 Teng2), which are only inhabited in the middle and
lower reaches of the Yangtze River. TGP will change the natural
environment of the middle reach, which may seriously affect Chinese
sturgeons. The breeding of this species has already been affected by the
Gezhouba project. Chinese paddlefish, which has only about 300 in numbers,
is currently inhabited at some 1,600 kilometers between Yichang and the
estuary of the river. TGP will reduce its habitat by 200 kilometers and
speed up the extinction of this species.
(4) TGP will aggravate the drought and affect the productivity of the
farmland in the lake areas.
The Four Lakes area, especially Lake Hong, has been suffering from
drought almost every year. Usually, nearly a half of flood water in this area
is released to the Yangtze River between January and April, when the water level
of the river is lower than that of the lakes. After the construction of TGP,
in order to improve the navigation condition of the Jing Jiang, the reservoir
will release water and elevate the water level of the river by 1-2 meters
during this period. As a result, the water level of the river will be higher
than that of the lakes in March and April, which will make the spontaneous
release of excessive water in this area impossible. Similarly, TGP will also
aggravate the drought in the lake areas further downstream, such as Lakes
Liangzi and Zhangdu. It is estimated that TGP will turn 20,000 hectares of
farmland in this area into marshland.
(5) TGP will terminate the land formation process and aggravate the
saltwater intrusion at the estuary.
Every year, the Yangtze brings more than a half billion tons of silt to
its estuary. About 50% of the silt ends up as sediments near the estuary,
which has been extending the coastline further into the sea by about 50
meters every year. As a result, the treasure of Sichuan, i.e., the soil brought
down by the river, has been moved to the estuary, creating a rich delta plain.
A direct result of TGP is to trap nearly 70% of the silt behind the dam,
which, besides silting up the reservoir and the waterway, will deprive the
estuary of the sediment material for the land formation process. In fact, TGP
will reverse the current equilibrium of the land formation. The clean water
downstream of the dam will cause not only coastal erosion in the lower
reach, but also the retreat of the coastline during October every year.
On the other hand, saltwater intrusion has already become a serious
problem for the estuary and the Huangpu Jiang. During dry season (i.e.,
March, April, May, October and November), salty sea water may come up to
Wusong, a suburb county of Shanghai, in the southern branch and Liuhekou
in the northern branch of the estuary. During the 243 days from the winter
of 1978 to the spring of 1979, a record-breaking dry period for the estuary,
Wusong had been surrounded by saltwater for 215 days, Yangshupu for 151
days, and Minhang for 73 days. The maximum chloride value had reached
3,950 parts per million (ppm) at the water factory of Wusong and 3,820 ppm
at Zhabei, while the normal value for drinking water should not exceed 250
ppm. It had caused an economic loss of 14 million yuans to Shanghai. The
controversial Baoshan Iron and Steel Plant, located in a suburb of Shanghai,
had to spend 120 million yuans to build a special reservoir in order to
reduce the chloride value to be below 200 ppm, as required by the imported
Salinization has also caused large losses to the agriculture. Nearly
200,000 hectares of farmland in Nantong and 35,600 hectares in Shanghai
have been seriously eroded by saltwater. They account for 42% and 10%,
respectively, of the total farmland in the two areas.
Because TGP will increase the downstream flow between January and
April, it will reduce saltwater intrusion during this period. However, the
reservoir will start to store water in October, when saltwater intrusion is
severe. As a result, TGP will reduce the river flow and aggravate the sea
water intrusion during October in every year. It is estimated that, unless
proper measures are taken in time, a total area of 2,000 square kilometers
can be affected (mostly located in the northern branch of the estuary).
About 60,000 - 100,000 hectares of farmland will be eroded by saltwater, which
will bring down the productivity of this area by 20%. Although the
salinization of soil is a reversible process, a large amount of capital and
manpower is required to bring it under control.
 The data in this and the last articles were taken from the Chinese
Academy of Science, 1988.
(the end of the series!)