◇Fan Zhongyan's "Kidney of the Yangtze River", "Kidney of the Yangtze River", which "holds distant mountains, swallows the Yangtze River, and lays endless bounds", is overwhelmed by the accumulation of silt.

The "sandalization" and "fragmentation" are becoming more and more intense, and problems such as "difficult water in the water nest" and "water dullness, dirty water and smelly water" occur frequently

  ◇On the 1:300,000 "Dongting Lake Water Conservancy Engineering Map", the reporter saw that on this map that is almost half a person tall, the East Dongting Lake is only as big as a palm, while the West Dongting Lake is about the size of a few fingernails.

The rest of the "Dongting Lake area" is actually land with a vertical and horizontal water network

  Dongting Lake swallows the Yangtze River and accepts the four major rivers of Xiangjiang, Zijiang, Yuanjiang and Lishui, and is called the "Kidney of the Yangtze River."

Its huge flood regulation and storage capacity has turned floods into danger for countless times in history, and has ensured that the vast areas of the middle and lower reaches of the Yangtze River turn from danger to safety.

  A reporter from "Liaowang" Newsweek conducted research in Yueyang, Yiyang, Changde and other places around the Dongting Lake area and learned that due to the accumulation of sediment and the changes in the relationship between the rivers and lakes, the vast and endless Dongting Lake in the past has now become fragmented. .

Among the fragmented water surfaces, many connected rivers have also been blocked.

In recent years, the Dongting Lake area has repeatedly encountered phenomena such as "high water level at the same flow, high water level with small flow, and extended maintenance time of medium and high water levels" in the flood season, which has increased the pressure of flood control and flood resistance; while in the dry season, there is "difficult water in the water nest". And the ecological problems and people's livelihood problems caused by "water staying, dirty, smelly".

  "If large-scale dredging is not implemented,'Eight Baili Dongting' may become a historical term." Some interviewed experts screamed that the accumulation of siltation over time caused the "kidney of the Yangtze River" Dongting Lake to suffer from "kidney stones".

After the related diseases are getting worse, Dongting Lake may face "kidney weakness".

It is recommended to implement large-scale dredging and auxiliary construction engineering measures to fundamentally restore the "kidney function" of Dongting Lake, improve the water environment of Dongting Lake, and achieve comprehensive effects such as flood control, ecology, drought resistance, and shipping.

 Weakening of water storage and water passing capacity

  During the high flood level this summer, the reporter took a small boat from the West Dongting Lake Nature Reserve Administration Bureau to the depths of the Great Lake for interviews.

The boat travels on the lake, looking around the water and the sky.

But the driver held the steering wheel tightly and drove carefully, not daring to "drive a boat" on the wide lake.

  Liu Kehuan, president of the West Dongting Lake Wetland Conservation Association, who is familiar with the water conditions in this area, told reporters that in flood season the lake looks like a "broad ocean", but in many places "the water is only deep in the back of the foot".

If you run the boat slightly carelessly, accidents such as collisions with underwater obstacles and grounding can easily occur.

  During the flood season, the reporter saw on the bank of Songhuhongdao in Anxiang County and Muping Lake Embankment in Nanzui Town, Yuanjiang City, the key areas of Dongting Lake flood control. The roofs of the two-story buildings in the villages inside the embankment are almost the same as the height of the surging Dongting Lake outside the embankment. The trend of "hanging lake" is shocking.

  At the national key flood reporting station-Chenglingji (Qilishan) Hydrological Station, Chen Jianxiang, director of the Yueyang Branch of the Middle Reach Bureau of the Yangtze River Committee, believes that the same flow of high water level, small flow high water level, medium and high water level maintenance time is prolonged, etc. The problem of declining water storage and water passing capacity of the Dongting Lake water system has become increasingly prominent.

  Many water conservancy experts in the lake area reported that flood control in the Dongting Lake area has experienced a phenomenon of "rapid rise and slow decline" in flood control in recent years.

Take Anxiang County, which has a levee of 420 kilometers, as an example. In less than 10 days in early July, all 16 hydrological stations in the county exceeded the warning water level, and some even exceeded the guaranteed water level.

Hydrological statistics show that from late June to mid-September this year, Dongting Lake maintained a high flood level for a long time.

Since Chenglingji Station reached the alert water level at 18:00 on July 4, the water level over-alert process in the Dongting Lake area lasted for 60 days, second only to the length of the Dongting Lake area over-alert time in 1998 and 1954.

  Pan Qunfang, chief engineer of Yuanjiang Water Resources Bureau, and Liu Wenxiang, chief engineer of Anxiang County Water Resources Bureau, told reporters that during this year's flood season, local water conservancy experts and cadres and the masses guarded the levee day and night for a long time, and there was a lot of work to inspect the levee. Dangers occur frequently, and the human, material, and financial resources for flood fighting are very expensive.

  Cadres from many places in the Lake District also reported that the flood fighting in recent years has changed from the past "short-term assault warfare" to "protracted warfare", "positional warfare" and "tug-of-war".

  "During the flood this summer, there was no danger of bank collapse in the Dongting Lake area. It seems that the'external injury' is not serious, but the'internal injury' is not light." A cadre from the lake area told reporters: "Because of the high water level, the slow receding water, and the long-lasting attack During the war, the lake area consumes a lot of manpower and material resources every day. At most, some prefecture-level cities invest as much as millions of yuan a day, and the local financial burden is heavy, which has a great impact on the production and life of the people in the lake area."

Endangering flood control and ecology

  Water conservancy experts in many places in the lake area told reporters that factors such as long-term sedimentation have reduced the area of ​​Dongting Lake from 6000 square kilometers in the mid-19th century to the current 2,625 square kilometers.

The siltation of Dongting Lake, which is shrinking amidst the changes in the "vicissitudes of life", is still giving birth to "riverization of lakes, shoalization of river channels, and landization of shoals."

  "In some years, if you look at Dongting Lake in winter from satellite imagery, you can barely see the water surface, leaving only the Xiang, Zi, Yuan, Liweilu river channels and the Caowei River and Xiangjiang River into the lake." A water conservancy expert opened the drawing in recent years. 1:300,000 "Dongting Lake Water Conservancy Engineering Map", the reporter saw that on this map, which is almost half a person tall, the East Dongting Lake is only as big as a palm, while the West Dongting Lake is about the size of a few fingernails.

The rest of the "Dongting Lake area" is actually land with a vertical and horizontal water network.

There are many white areas in the hinterland of limited lakes in the picture. They are the beaches that have developed in recent years. Except for the "sea" when the flood comes, most of the rest are "mulberry fields"...

  Water conservancy experts pointed out that the siltation problem of Dongting Lake has accumulated year by year. In addition to increasing flood control pressure, there are also multiple negative effects:

  One is the weakening of storage capacity.

  Shen Xinping, director of the Dongting Lake Water Conservancy Affairs Center of Hunan Province, said that the sediment transport data of the hydrological station showed that from 1956 to 2019 the sedimentation of the Dongting Lake area was 5.215 billion tons, of which the average annual sedimentation volume before the completion of the Three Gorges Project was 114 million tons.

It is particularly obvious that the average annual flow of the Yangtze River into the Dongting Lake from the Yangtze River to Dongting Lake has been changed from the fifth of the 20th century due to the sedimentation of the "four mouths" water system and the discharge of clear water after the impoundment of the Three Gorges. The 133.2 billion cubic meters in the 1960s decreased to 47.9 billion cubic meters today. The flood diversion ratio of the peak flow during the flood season was reduced from 40% to about 25%, and the flood diversion function of the "Kidney of the Yangtze River" was significantly weakened.

  Shen Xinping told reporters that the volume of Dongting Lake in 1949 was 29.3 billion cubic meters, but now it is only 16.7 billion cubic meters, which is only twice that of Dongjiang Lake Reservoir, a large reservoir in Hunan Province.

In contrast, Fuxian Lake in Yunnan Province is only one-tenth the area of ​​Dongting Lake, but its volume is about 20 billion cubic meters.

"Dongting Lake looks like a large area, but in fact the water is very shallow, its capacity is very small, and its capacity for regulation and storage is getting weaker and weaker," he said.

The second is the attenuation of river and lake water systems.

  The reporter learned from the Dongting Lake Water Affairs Center of Hunan Province that changes in the relationship between rivers and lakes and sedimentation have caused the Yangtze River to fail to enter and store water in Dongting Lake during the dry season. The water level of rivers and lakes decreases, seasonal droughts and dry-flow water shortages are increasing. Highlight.

Especially in the "four mouths" water system areas, the rivers are severely cut off.

Except for the Songzi West Branch, other rivers were dry-off for 137 to 272 days per year. The Ouchi West Branch was dry-off for 336 days in 2006, which affected the irrigation and drinking water of 3 million mu of arable land and 2.8 million people.

 The third is the deterioration of the ecological environment.

  At present, in some places of Dongting Lake during the dry season, the phenomenon of "water staying, dirty, and smelly" can easily lead to diseases such as schistosomiasis and various stone diseases.

Some wetland beaches have degraded functions, such as Lake Luma, a natural spawning ground for fish with an area of ​​30,000 mu.

In addition, the vegetation in some areas of the lake area has succeeded from a wetland type to a mesotropic meadow, and the trend of wetland fragmentation has become increasingly obvious.

With the decline of biodiversity, the ecological environment in some places in the Dongting Lake area is not conducive to the survival and migration of wild aquatic animals and plants, and the water environmental capacity of the inner lake, the Yahe River and the outer rivers has decreased.

 Fourth, industry development is limited.

  Many places in the "land of fish and rice" rely on the development of agricultural production such as rice and shrimp industries to make ends meet.

Today, the poor water quality and lack of water in the lake area have become the main constraints.

Seasonal water shortages, water quality-type water shortages, and regional water shortages. In some parts of the lake area, long-distance cross-regional water transfer and multi-level water extraction are required. The economic development cost is very high, and sometimes even human and livestock drinking water is tight.

 Fifth, the general aviation guarantee rate has been reduced.

  Affected by the shrinkage of the Dongting Lake area and the lowering of the water level in the lake area during the dry season, the navigation conditions of the main waterways in the Xiangjiang River, Yuanshui Weilu, Songhu-Lizi Waterway and other lake areas have deteriorated. Ships stranded, blocked, and beach hazards worsened during dry seasons, causing inconvenience to ship navigation, and accidents happen from time to time.

  Not long ago, Hunan was approved to establish a free trade zone. Among them, the Yueyang area on the banks of the Yangtze River and East Dongting Lake will assume the important task of Hunan's economic and trade hub.

  However, a shipping expert in Yueyang told reporters that due to the blockage of the channel, the 10,000-ton ship could not maintain navigation throughout the year in the waters of Dongting Lake near the Yueyang area.

Deeper in the lake area, the navigation capability is weaker.

This situation constitutes a serious constraint on the development of Hunan's shipping economy.

  "Cracking Stones" and "Removing Stones" Simultaneously Save the "Kidney of the Yangtze River"

  Many water conservancy experts in Dongting Lake District, counties and cities believe that large-scale river and lake dredging in the Dongting Lake area is a major strategic measure to fundamentally improve the water environment of Dongting Lake.

One is river dredging.

  Dredging the "four ports" entrances and flood channels, implementing "diversion from the river to the lake", and simultaneously digging and storing water and diverting water into the lake.

Through the dredging of rivers and lakes, the flood discharge section will be increased in the wet season, the flood water level will be reduced, and the flood control pressure will be reduced; in the dry season, the water storage capacity will be increased, the cut-off time will be shortened, and the water shortage will be relieved; the navigation capacity will be improved to form a Yueyang city The large Dongting Lake shipping hub system with Lingji as the center allows large-scale passage of ships of more than 5,000 tons, reviving the advantages of Dongting Lake water transportation logistics.

  The second is engineering assistance.

  It is recommended to build gates to control some key nodes in the Dongting Lake water system to give full play to the functions of flood discharge during the flood season and water storage at the end of the flood season.

Through natural and artificial means, the construction of rivers and rivers, rivers and lakes (reservoirs), and lakes and lakes (reservoirs) and other connection projects, maintain the connection and circulation of water bodies in different regions.

It is also recommended to open up the flood channels, branch rivers, canals, plain reservoirs and inner lakes of Dongting Lake.

Shen Xinping believes that the construction of sluices to control the upstream and downstream branches of branch rivers such as the Catfish in the Ouchi River system, the Chenjialing River and the western branch of the Ouchi River, and the Dahukou River in the Songzi River system. Water shortage during dry season.

  Lake area water conservancy experts believe that the implementation of large-scale Dongting Lake dredging projects and related projects can significantly change the water environment of the Dongting Lake area and significantly improve the water security capacity of residents in the lake area and for industrial and agricultural production; the sediment generated during dredging is used to reinforce the first-line flood control dikes. It will also greatly improve the flood control standards of the Dongting Lake embankment.

For this project that benefits the country and the people, it is recommended that the state incorporate the "14th Five-Year Plan" and the special plan for river and lake dredging management, and establish and implement the project as soon as possible.

(Reporter Su Xiaozhou Zhou Nan)