Academician: the Three Gorges Project and the south to North Water Diversion Project is a huge disaster for ecology!
Release date: November 5, 2019 14:45:36
In today's China, water conservancy experts and ecological experts seem to have become natural enemies. In 2013, the issue of "Yangtze River ecosystem collapse" triggered this confrontation again.
The Yangtze River, as the largest river in China and Asia, nurtures the Chinese nation. The development of the Yangtze River has also reached its peak in recent years. In addition to the Three Gorges Project and the South-to-North Water Transfer Project, it is also directly reflected in the upstream cascade development of the Jinsha River.
Recently, Wang Dongfang weekly interviewed Cao Wenxuan, a researcher at the Institute of aquatic biology of the Chinese Academy of Sciences and academician of the Chinese Academy of Sciences, on the ecological problems of the Yangtze River. He is one of the oldest Yangtze River Ecosystem experts in China and a major advocate of the 10-year ban on fishing in the Yangtze River. This policy is considered to be the last chance to protect the ecology of the Yangtze River.
In recent years, he has not listed a series of "great conservation effects" of Baiji in the Yangtze River, but he has not listed a specific protection function of Baiji in a series of national conservation efforts.
In addition, the population of the Yangtze finless porpoise, a second-class protected animal, has also decreased sharply: from 1800 in 2006 to 1040 in 2012, the degree of endangerment has increased.
In his opinion, how to balance the demands of different interest groups is the real key to solve the ecological problems of the Yangtze River.
The relationship between the lake and the lake has been greatly affected
Oriental weekly: Recently, there is a saying that the Yangtze River ecosystem is on the verge of collapse. What do you think of this problem?
Cao Wenxuan: great changes have taken place in the ecosystem of the Yangtze River system, including the great impact of the Three Gorges Project on the ecology of the Yangtze River.
Generally speaking, the most direct and important factor affecting the ecology is the overfishing of cool fish. Fishing gear and fishing methods such as "enchanting array" and "electric fishing" are far more harmful to fish resources than the "jedu net" in the ocean. Other factors include water conservancy and hydropower project construction, river and lake barrier, lake reclamation, industrial and mining wastewater discharge, agricultural non-point source pollution, etc. The change of ecological environment caused by dams is irreversible. The development of water elevator in the upper reaches of the Yangtze River will have a superimposed impact on the ecosystem of the Yangtze River. Its future impact on the ecosystem and biological survival of the Yangtze River can not be foreseen.
When we wrote the environmental impact report of the Three Gorges Project in 1989, we predicted that the completion of the Three Gorges reservoir would lead to changes in hydrological characteristics such as water temperature and flood process of the Yangtze River. The spawning period of "four big fishes" (black carp, grass carp, silver carp and bighead carp) will be postponed, and the spawning period of the four big fishes will be postponed from the end of April to the beginning of may now; the spawning period of Chinese sturgeon was originally from late October to early November, but now it has been postponed to late November.
When the spawning time is delayed, the food of plankton, aquatic grass and other fish will change, and the ecological factors will change, which will have a great impact on the growth of fish fry, which is not conducive to the continuation of the species. This problem is very serious.
Taking Jinsha River as an example, it is now in the trend of cascade development. Four hydropower stations, such as Xiluodu downstream, are very high dams, some of which are more than 200 meters high. A total of 13 hydropower stations are planned to be built in the middle and upper reaches of the Jinsha River.
Influenced by the East Asian monsoon, the runoff of the upper reaches of the Yangtze River varies greatly in the wet season and dry season, and the water level difference in some river valleys is more than 20 meters. The form of cascade development of upstream hydropower stations has changed the ecology of river waters. The river water changed from a torrent to a slow flow, which not only changed the hydrological characteristics such as flow velocity and flow pattern, but also changed the spatial and temporal distribution pattern of runoff and affected the survival of endemic fish in the basin.
In particular, there are many fishes in the upper reaches of the Yangtze River that are suitable for living in the rapids. These fishes eat benthos in the shallow beaches. After the completion of the dam, the flow velocity will slow down, the river will become deeper, the illumination will be insufficient and the sediment will deposit, which will result in a large number of benthos unable to grow, which will not provide enough food for fish, which will have a great impact on the survival of more than 120 species of endemic fish in the upper reaches of the Yangtze River.
If the Jinsha River, Yalong River, Dadu River, Minjiang River and other rivers are built with less than two dams in the construction of hydropower stations, a lot of fish and many species can be protected by setting up protection zones together in the rivers and their tributaries of the river without dam construction.
However, this kind of assumption is more difficult now. They are all fighting for territory. For example, the Jinsha and Yinjiang hydropower stations under construction in the middle reaches of the Jinsha River are not included in the hydropower planning of the Yangtze River Basin. It is the local government of Panzhihua that is constructing them. This is wrong. The construction of these two non planning hydropower stations will probably make the last habitat and breeding ground of the fish disappear.
After the completion of the Three Gorges Dam, the backwater area of the reservoir has reached more than 600 kilometers, which has been traced back to the Xiaonanhai above Chongqing. The survival of some endemic fish, such as the round mouth copper fish and the rock carp, which are difficult to survive in the still water, has been severely challenged.
With the climate change, the water quantity is reduced, the glaciers shrink, the frozen soil degenerates, and the water storage capacity of the frozen soil decreases; at the same time, after the dam is built, the water surface area of the reservoir increases and the evaporation capacity increases obviously. For example, after the completion of Xiluodu and Xiangjiaba, the runoff of local rivers decreased by 3%.
Compared with the Three Gorges Hydropower Station in recent years, the average runoff of Yichang hydropower station is more than 50 billion cubic meters. The decrease of Yangtze River runoff will lead to the advance of dry season and lower water level in Poyang Lake and Dongting Lake.
Chain reaction of South to North Water Diversion Project
Oriental weekly: the Yangtze River water conservancy development did not start from the Three Gorges Project. What was the impact of the past projects?
Cao Wenxuan: in the late 1960s and early 1970s, when the impact of Gezhouba was demonstrated, it was mainly the barrier to the Chinese sturgeon.
The impact of the Three Gorges Dam on the Yangtze River ecosystem is reflected in many aspects. 95% of the fish larvae discharged from the sluice gate of the Three Gorges dam are dead fish.
In terms of sediment, more than 70% of the sediment is deposited in the Three Gorges Reservoir area, and clear water is coming down. Clean water is not necessarily a good thing, because sediment can absorb a lot of pollutants. Without sediment, pollutants can not be absorbed, and river pollution will be aggravated.
Moreover, due to the scouring of clear water, the riverbed of Jingjiang river reach is washed deep, resulting in the water level of the Yangtze River falling. When the water level of Chenglingji falls to 23 meters, the water in Dongting Lake is drained out, and the lake enters the dry season ahead of time.
In addition, the coastal wharf will also be rebuilt. For the water ecology, many of the river's central banks have been scoured down. The coastline of Chongming Island and Changxing Island in the estuary of the Yangtze River is shrinking due to the impact of clear water scouring. In addition, the erosion of the Yangtze River dyke.