Academician: the Three Gorges Project and the south to North Water Diversion Project is a huge disaster for ecology! (2)
Release date: November 5, 2019 14:45:36
Oriental weekly: after the completion of the Three Gorges project, the largest water conservancy project in the Yangtze River Basin is the south to North Water Diversion Project. How do you see its impact?
Cao Wenxuan: for inter basin water transfer in the upper reaches of the Hanjiang River, one third of the water volume of the Hanjiang River should be transferred to the north. In addition to the first phase of the Middle Route Project of the south to North Water Diversion Project, there is also the project of "diverting water from the Han River to the Wei River". Therefore, the water volume in the middle and lower reaches of the Hanjiang River is greatly reduced. In the dry season, especially in January and February, the Yangtze River water may flow back into the Hanjiang River.
According to the plan, the cascade reservoirs of Hanjiang River have been built to Xiangfan. At the same time, the Tangbai River, which is seriously polluted by the upstream tributary, flows into the Hanjiang River. With the sluggish water flow in the middle and lower reaches of the Hanjiang River, eutrophication will occur in the middle and lower reaches of the Hanjiang River, resulting in a large number of algae growth and water blooms, thus threatening the water source of Hankou water plant. In order to solve these problems, it is decided to implement "diverting water from Yangtze River to Hanjiang River" and transfer the Yangtze River water from Shashi to Xinglong.
After the implementation of "diverting water from the Yangtze River to the Han Dynasty", it will certainly affect the Dongting Lake. Therefore, Dongting Lake proposed to build a sluice in Yueyang to stop the water, otherwise the dry season of Dongting Lake would be greatly advanced.
The west route of South to north water transfer will have a greater impact on the ecological environment of the upper reaches of the Yangtze River. Relatively speaking, the ecosystem in the upper reaches of the Yangtze River is more fragile, and the production and life of the water diversion area will be affected, which needs to be treated carefully.
In the future, the second phase of the middle route of South to north water diversion is still difficult to say. Shaanxi Province has also transferred a lot of water from the Han River to the Wei River. Now there is not much water in the Hanjiang River. Hubei Province will also strive to protect the Hanjiang River. However, as far as the eastern route of the south to North Water Diversion Project is concerned, the impact on the Yangtze River is not so obvious. The Middle Route Project of South to North Water Transfer Project has great influence.
Looking at Oriental weekly: what is the situation of the discharge of domestic sewage and industrial sewage along the Yangtze River?
Cao Wenxuan: now, the state attaches great importance to sewage treatment and has built many sewage treatment plants. But the daily sewage treatment needs to consume a lot of electricity, some places do not have enough operating funds, only symbolic operation when the leaders come to check.
The pollution problem of the Yangtze River is mainly reflected in the coastal pollution zone. Generally speaking, the sewage pollution of the Yangtze River is still controllable, because it is the drinking water source of cities along the Yangtze River. However, the safety of drinking water should not be underestimated, and toxic pollutants should be strictly controlled. For example, in the 1970s and 1980s, a sign was erected next to the Yangtze River sewage outfall of Shashi pesticide factory in Hubei Province, which said "no drinking for human and livestock within two kilometers". However, the fish passing by did not know the water quality here, and many passing fish were poisoned here.
In response to drinking water pollution, we should start to prepare water sources for combat readiness. Ecological restoration of some lakes and reservoirs should be put on the agenda to keep the water quality clean. I once suggested that Liangzi Lake should be used as the water source for war preparedness in Wuhan.
Some lakes have become stagnant
Oriental weekly: how about the ecological environment of lakes in the middle and lower reaches of the Yangtze River?
Cao Wenxuan: originally, many lakes in the middle and lower reaches of the Yangtze River, such as Dongting Lake, Poyang Lake, Honghu Lake and Donghu Lake, are connected to the river, and the lakes are rich in bait. After spawning in the high water period of the Yangtze River, the fry float to the lake to hatch and grow. After half a year, the fry can grow to more than 1 jin, and the larger fish can exceed 3 jin. At present, the Yangtze River is connected with rivers and lakes, and the construction of sluices blocks the communication between the Yangtze River and lakes, and affects the hatching and growth of juvenile fish. This is one of the important reasons for the rapid decrease of fish resources in the Yangtze River.
Due to climate change, the impoundment of the Three Gorges from September to October, riverbed erosion and other reasons, the water level of the Yangtze River has dropped and the dry season of lakes has been advanced. Poyang Lake has long been in the situation of "a large area in flood season and a line in dry water". It is necessary to build sluices at the places where the water flows into the Yangtze River. The sluice is opened in flood season and blocked in dry season. In this way, the lake water is controlled at 12 meters in December, which is conducive to the habitat of migratory birds. In 2007, Jiangxi initially planned to store water to 27 meters. After the plan was revised, the highest water storage was 16 meters in September and 12 meters in November.
In the past, we were opposed to building sluice gates for water storage in lakes, but later we realized the favorable side of water storage. For example, 99% of the white crane winters in Poyang Lake. They feed on the underground stems of Vallisneria angustifolia. The water storage protects the wetland and the migratory birds living here. In addition to the habitat of migratory birds, it is also conducive to the survival of finless porpoises.
The largest group of finless porpoises is in Poyang Lake, with 450 in 2012 and 90 in Dongting Lake. If the water level is too low in winter, the finless porpoise can hardly survive
It is not necessarily a bad thing to build sluices and store water. But I have repeatedly stressed that fishermen should be transferred to other industries. Fishermen in Poyang Lake use the "enchantment array" to fish, and small fish are not let go. Some people use electric fishing, which causes serious damage to fish resources. It is very difficult for finless porpoises to find fish to eat. If they enter the "enchanting array", they will be trapped in it. At the same time, we should strictly ban the fishing gear and fishing law that destroy the fish resources according to the "Fisheries Law".
Oriental weekly: it is said that the ecosystem of the East Lake is facing a very serious challenge.
Cao Wenxuan's ecosystem is worse. In the past, there were a lot of wild ducks and waterfowl wintering in Wuhan East Lake, but now they are not. The reason is that there is no food such as fish, shrimp and bitter grass.
After graduating from university in 1955, I was assigned to work in the Institute of aquatic biology, Chinese Academy of Sciences. Now it has been 58 years. I have witnessed the changes of the East Lake.
In the early 1960s, there were 83 species of aquatic plants belonging to 53 genera and 29 families in Donghu Lake. By the early 1990s, the number of aquatic plants decreased to 52. In 2013, there were only 14 species of aquatic plants in the lake. In the 1960s, there were 79 species of fish in Donghu Lake, and now there are less than 20 species.
The ecosystem of Donghu Lake was destroyed, the biodiversity decreased, and the water self purification function was also lost. At present, there are many organic pollutants in the sediment of Donghu Lake. Donghu Lake, which used to be the water source of six waterworks, can't even swim now. Now the East Lake is a stagnant water.
In order to restore the original vitality of the East Lake through ecological restoration, it is particularly important to restore the connection between the lake and the lake and restore the seasonal fluctuation of water level. In winter, the lake water is drained to the Yangtze River to lower the water level, so that the lake bottom can be better exposed to sunlight. The organic pollutants in the lake bottom can be degraded by ultraviolet radiation, so that aquatic plants can recover. In the second year, the plants at the bottom of the lake germinate and grow again, so as to absorb more nitrogen, phosphorus and other elements, so as to alleviate the eutrophication of water quality.
At the same time, we should give up fishing products and do not raise a large number of one or two kinds of fish. After restoring the connectivity between the lake and the lake, the fish in the lake will form a natural community structure, which can develop the fishing industry. In addition, the sewage discharged by enterprises and institutions around the East Lake should be separated and drained away by sewage pipes, which can not be discharged to the East Lake.
On the other hand, the ecosystem of Taihu Lake is not optimistic for two reasons. First of all, the industry in Taihu Lake area is relatively developed, especially township enterprises discharge a large amount of sewage into Taihu Lake; in addition, fish farming in fences has seriously damaged the original ecosystem of Taihu Lake.
There is no fish in the Yangtze River now
Oriental weekly: what is the invasion of alien fish species in the Yangtze River system?
Cao Wenxuan: there are more and more alien species invading, but they are different in different places. For example, in Dongting Lake, some foreign fish compete with native fish for food, and some fish eggs and juveniles are also eaten by alien invasive fish. There are many kinds of foreign fish, which have a great impact on the living environment of local fish. Alien fish invasion is a very serious problem.
Now the Yangtze River system has found sturgeon and Amur which belong to Heilongjiang River Basin, as well as Russian sturgeon, Siberian sturgeon and hybrid sturgeon introduced from abroad. The reason is that most of these sturgeons are not listed as protected animals. Some people breed in the Yangtze River water system. When some cages have problems, they run out into the Yangtze River. What worries me most is that we may hybridize with these sturgeons, which are endemic to the Yangtze River, and change the genetic nature of the species.
Oriental weekly: during the construction of the Three Gorges project, a national nature reserve for rare and Endemic Fishes in the upper reaches of the Yangtze River was established. What is its situation?
Cao Wenxuan: during the construction of the Three Gorges project, a National Nature Reserve of rare fish in Hejiang Leizhou band in the upper reaches of the Yangtze River was built. Later, due to the construction of Xiluodu and Xiangjiaba hydropower stations on the Jinsha River, the nature reserve was further adjusted to the lower part of Xiangjiaba, and the Chishui River was added to the mouth of the masang River in Chongqing. In 2007, Chongqing wants to build Xiaonanhai hydropower station, which is more than 20 kilometers from Xiaonanhai to Mashang River Estuary. This was originally an experimental area, and the river section below the Mashang river mouth needs to be adjusted into a protected area. The central government has basically agreed to the adjustment here. The Ministry of environmental protection has defined the boundary, which has not yet been drawn up. In the process of adjustment, the core area of rare and endemic fish nature reserve has not been adjusted.
Only in the first adjustment of the nature reserve, the state allocated 382 million yuan. Guizhou, Yunnan, Sichuan and Chongqing all took the money, especially Guizhou. However, some people got the money to buy boats, cars and houses, and the management was not in place. The phenomenon of catching endemic fish in the nature reserve has been banned for many times. How to "protect"?
In fact, in the past 20 years, with the development of water resources in the Yangtze River, a lot of work has been done, such as the implementation of the Yangtze River water resources protection plan, the establishment of a fishing ban period, and so on. However, in my opinion, the effect is not very good, and fishing gears that destroy fish resources can not be well prohibited.
Jialing River and Hanjiang River are basically electric fish boats, and the "enchanting array" of fishing in Dongting Lake and other places is widespread. Due to the extinction of Baiji dolphin and Acipenser Acipenser, the population of finless porpoise has dropped sharply. The basic reason is the lack of food.
In recent years, the state releases fry in the Yangtze River every year. In 2010, a total of 710 million yuan was invested to release economic species, including 250 million yuan from the Yangtze River. According to the data, the fish production in Hubei, Hunan and Jiangxi provinces in the middle reaches of the Yangtze River is increasing every year, but the fishing yield is not optimistic.
Hubei released 570 million fry in 2010, which should be reflected in the yield in 2011. However, in 2010, the freshwater aquaculture output was 3.2672 million tons and the fishing output was 263600 tons. In 2011, the freshwater aquaculture output was 3.3562 million tons, and the fishing output was 205900 tons. The fishing output decreased by 57700 tons.
Representative are also known as the Yangtze River's "three fresh" shady fish, swordfish, dark line Oriental, they are extremely endangered.
In the 1960s, the output of shad was stable, with annual output between 300 tons and 600 tons. In the 1970s, the output fluctuated greatly. In some years, the output was less than 100 tons, and in some years it was more than 1600 tons. In the 1980s, the average annual output was only 79 tons, and in 1986 it was only 12 tons. At the end of the 1980s, there was no fish flood.
At the end of spring and the beginning of summer every year, shad head up from the sea to Ganjiang River in Poyang Lake system to lay eggs. After half a year of growth in Poyang Lake, the young fish will swim back to the sea. Fishermen will cast nets around the mouth of the lake to salvage the young fish, which will be dried in the sun to feed poultry. In this way, the shaddock in the Yangtze River Basin is extinct.