2020-07-16

Yangtze River Flood Control in the Post-Three Gorges Era:Beware of major floods in the entire basin

By yqqlm yqqlm
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On July 2, the outflow of the Three Gorges Reservoir was controlled at an average daily rate of 35,000 cubic meters per second. Figure/Zhongxin

The Yangtze River flood control system in the post-Three Gorges era

Journalist/Yang Zhijie

The Yangtze River’s first flood red warning this year appeared in Poyang Lake.

At 13:00 on July 10th, the Hydrology Bureau of the Yangtze River Water Conservancy Commission (hereinafter referred to as the Yangtze River Commission) of the Ministry of Water Resources upgraded and released the Poyang Lake Hukou near the river section, Poyang Lake area red flood warning, this is the highest level of flood warning signal. One day later, the red alarm sounded again, and the Hydrological Bureau of the Yangtze River Commission continued to issue red early warnings for floods in the section of the middle and lower reaches of the Yangtze River from the Jiujiang to Hukou and Poyang Lake areas at 12:00 on July 11. The warning was quickly verified. At 7:00 on July 12, the water level of the Poyang Station of the Rao River in Jiangxi exceeded the 1998 water level by 0.13 meters, breaking the historical extreme value since the hydrological record, and the flood control work of the whole province of Jiangxi entered a wartime state.

Poyang Lake is the last large-scale”reservoir” before the Yangtze River entered the lower reaches. If the Poyang Lake is lost, the Yangtze River floods will be discharged directly, which will bring great pressure for flood control in the lower Yangtze River. But now, this”reservoir” has been growing bigger and bigger. The National Satellite Meteorological Center has recently cooperated with the Jiangxi Meteorological Bureau to conduct scientific monitoring and assessment of the changes in the main body of Poyang Lake and the surrounding waters in Jiangxi Province, using satellite remote sensing monitoring results for nearly 10 years since 2010 and combining meteorological observation data for nearly 60 years. The results showed that the main body of Poyang Lake and the surrounding water area reached 4206 square kilometers, the largest in the past 10 years.

The flood control pressure of cities in the lower reaches of the Yangtze River is also increasing as the area of ​​Poyang Lake expands. This year’s torrential rains are extremely extreme and break through historical records, and are still prevalent in the middle and lower reaches of the Yangtze River. This inevitably raises worries. Will there be a flood in the Yangtze River similar to that in 1998? It was the worst flood in China in the past three decades, causing 4,150 deaths and leaving a very profound mark on China.

On July 13th, the Ministry of Water Resources introduced at the State Council’s policy briefing that the current water level below the Jianli River and Dongting Lake, Poyang Lake and Taihu Lake below the Jianli River Still in the state of super alarm. Numerous predictions indicate that there will still be a large river basin flood this year, and the Yangtze River flood control system will once again face a severe test.

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On the morning of July 12, Youdun, Poyang County, Shangrao City, Jiangxi Province In the streets and towns, many villages were immersed in the flood, and some houses were washed away. Figure/People’s Vision

Beware of floods throughout the basin

Poyang Lake is China’s largest freshwater lake, and plays an important role in flood control and storage in the Yangtze River Basin.

The five major rivers in the Poyang Lake Basin merge into Poyang Lake, and after being stored, they are injected into the Yangtze River from the estuary. At the same time, during the flood period of the main stream of the Yangtze River, Poyang Lake accepted that the Yangtze River floods poured into the lake, stored the Yangtze River floods, and relieved the upstream flooding pressure.

In the afternoon of July 7, Poyang Lake experienced the first river backwatering this year. At the foot of Shizhong Mountain at the intersection of the Yangtze River and Poyang Lake, the north of the lake turned into the south of the river, and the water of the Yangtze River poured into Poyang Lake. Chen Xianping, deputy director of the Hukou County Emergency Management Bureau, explained that the water level of the Yangtze River in Poyang Lake has risen rapidly by more than 40 centimeters due to heavy rainfall in recent days. Due to the large amount of incoming water from the Yangtze River, the Poyang Lake has been affected by the water level of the Yangtze River. The phenomenon of backflushing.

Inverted irrigation of river water will inevitably cause the water level of the Poyang Lake area to rise. According to the latest statistics from the Jiangxi Provincial Flood Control and Drought Relief Headquarters, as of 17:00 on the 11th, torrential rains, floods, waterlogging and other disasters have caused more than 5.21 million people in the Poyang Lake Basin, more than 430,000 people were resettled and 455 thousand hectares of crops were affected.

Zhou Jianjun, chief researcher of the Institute of River and Ecology, School of Civil and Hydraulic Engineering, Tsinghua University, told China News Weekly that it is normal for rivers to be backfilled during the flood season in Poyang Lake. The backflushing situation is not serious compared with previous years. He explained that the total water level of the Yangtze River is higher than the water level of Poyang Lake when backflow occurs. However, this year’s data seems that the water level of Hankou upstream and downstream Datong water level, which are closer to the lake mouth, are still about one meter away from the guaranteed water level, and the water level of the lake mouth has approached the guaranteed water level, which shows that only the single-point water level of the lake mouth is higher. The water level at the upstream and downstream observation stations has not exceeded the guaranteed water level.

At 16:00 on the 12th, the water level of the Poyang Lake Hukou Station was close to the guaranteed water level of 22.50 meters. In response, the National Defense General Administration decided to upgrade the flood response level III emergency response to level II. A day ago, on July 11, the Jiangxi Provincial Flood Control and Drought Relief Headquarters upgraded the flood control level II emergency response to level I, which was also the first time that Jiangxi initiated the response since 2010.

An expert on finger defense in the province said that in the face of rising floods, it is necessary to request the support of troops, armed police and other fresh troops in advance if necessary. Make preparations for organizing the transfer and resettlement of personnel in flood storage and detention areas, and blasting at flood diversion outlets. Activate flood diversion channels and flood storage detention areas in a timely manner. Once the commissioning order is issued, floods are immediately distributed to ensure the relief of pressure on important dikes. In response to the local government’s demand for troops, the Jiangxi Military Region coordinated a certain army unit in the eastern theater, and 1,500 officers and soldiers arrived in Poyang County on the evening of July 11. In addition, the Rocket Army, Armed Police and Reserve Forces who have come to the rescue successively have gathered thousands of troops along the Poyang Lake.

“The tension in the Poyang Lake area must definitely be taken seriously, but at present it seems that the main stream of the Yangtze River will not have too serious problems.” Zhou Jianjun told”China News””Weekly”, the Hukou station has not exceeded the guaranteed water level, and the increase in the flow rate in the Poyang Lake area is also slowing down. More importantly, the water level of Datong in the lower reaches of Poyang Lake is still more than 1 meter lower than the design water level,”This shows that the lower reaches of the Yangtze River (flood discharge) There is room for problems in Anhui, Nanjing, Jiangsu and other places at present.”

But he reminded that what is most worrying now is the sudden rainstorm in the upper reaches of the Yangtze River. If the Three Gorges are not successfully intercepted and the upstream and downstream floods are superimposed, problems will easily occur. According to the weather forecast, from July 13th to 16th, the main heavy rainfall area will move southwards after a short northward movement, and then come to the middle and lower reaches of the Yangtze River again, with a large degree of coincidence with July 4th to 7th heavy rainfalls. At that time, heavy rain may still hit the Poyang Lake Basin. In this regard, Zhou Jianjun believes that even if there is heavy rainfall, as long as it does not overlap with the upstream flood, it will not be too serious. The Yangtze River channel below Datong can pass 80,000 cubic meters per second of flow, and the water beyond Poyang Lake can flow into the tributary of the Yangtze River. , Can also be safely discharged.

The Yangtze River Water Conservancy Commission once predicted in April that the overall deviation of the meteorological year in the Yangtze River Basin in 2020 is likely to cause regional major floods in the Yangtze River. Large river basin floods may occur. In early July, the Yangtze River Commission stated that it still maintains this judgment based on the current status of meteorology and hydrology and supplementary analysis.

Cheng Xiaotao, member of the Expert Committee of the National Disaster Reduction Committee and former director of the Institute of Flood Control and Disaster Reduction of the China Institute of Water Resources and Hydropower Research, explained to China News Weekly, usually There are many manifestations of the major floods in the Yangtze River Basin:one is called”lower flood”, the rain belt is mainly distributed in the middle and lower reaches of the Yangtze River, usually in June; the other is called”upper flood”, mainly in Sichuan on the upper reaches of the Yangtze River , Chongqing area, generally occurred in July and August.

There is another kind of great flood in 1998. The time of”lower flood” was postponed to July, and the”big flood” met, forming a complete Flood in the basin.”Floods also have multiple manifestations. One is that the peaks are extremely large and last a long time, such as the 1954 flood. The flood peaks of the 1998 flood were not that large, but they were one peak after another, eight consecutive.” Cheng Xiaotao said.

“The latter half of the month is very important.” Zhou Jianjun said that the flood season in the Yangtze River is more prone to “seven times and eight times”. At present, flood development is mainly concentrated In the middle and lower reaches of the south of the Yangtze River, it moved to the north and upstream of the Yangtze River in early August. This means that the upper reaches of the Yangtze River may still have worse flood conditions. The most important thing at present is to stabilize the upper reaches.

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July 13th, Wuhan, Hubei, citizens are about to be Take photos in front of the submerged Wuchang Huanghuaji Pavilion. Figure/People’s Vision

Excessive dependence on the Three Gorges?

In order to reduce downstream pressure, the Yangtze River Commission dispatched the Three Gorges Reservoir>> span> Since July 11, the average daily outflow will be reduced from the current 25,000 cubic meters/second to 22,000 cubic meters/second, to reduce the pressure of flood control in the middle and lower reaches as much as possible. Nevertheless, Chen Guiya, deputy chief engineer of the Yangtze River Water Conservancy Commission of the Ministry of Water Resources, said that because the mouth of the Poyang Lake is far from the Three Gorges Reservoir, and the water from the Poyang Lake system is relatively large, the Three Gorges Reservoir Regulation has a great effect on the water level of the Poyang Lake. limited.

Zhou Jianjun further explained that the Three Gorges will block or release floods to a certain extent and will have little impact on the downstream. Even if the Three Gorges mostly passes through 10,000 cubic meters of water flow, because the distance is too far below Wuhan, the flow will not increase too much. It cannot be understood that the upstream flow rate is shifted down. For example, the flow rate that was originally 80,000 cubic meters per second is now superimposed to 90 million cubic meters per second.

“Objectively speaking, the middle and lower reaches of the Three Gorges Gang must have reduced certain burdens, but whether this is appropriate is still debatable.” According to Zhou Jianjun, according to the Three Gorges’ Dispatching regulations, the Three Gorges should not control the downstream, but only intercept large floods, mainly to keep Jingjiang safe. The Jingjiang River is another name for the Chenglingji section of the Yangtze River from Zhicheng City, Hubei Province to Yueyang County, Hunan Province, with a total length of about 360 kilometers.

In May 2010, the National Flood Control and Drought Relief General Headquarters pointed out in the”Response to the Three Gorges-Gezhouba Hydro Project’s 2010 Flood Season Dispatching and Operation Plan”,”When When small and medium floods occur in the upper reaches of the Yangtze River, according to real-time rain conditions and predictions and forecasts, the Three Gorges Reservoir does not yet need to implement flood control compensation and dispatch for the Jingjiang or Chenglingji Reach, and when it is fully assured to ensure the safety of flood control, the Three Gorges Reservoir can be dispatched by camera”.

As of July 12, the water level of the Three Gorges was 152.16 meters. In principle, the water level of the Three Gorges Reservoir will be controlled according to the flood control limit water level of 145 meters during the flood season to ensure sufficient flood control reservoir capacity. Zhou Jianjun worried that the dispatch of the Three Gorges was a waste of flood control capacity. Although the current floods are mainly concentrated in the middle and lower reaches of the south of the Yangtze River, they will generally move to the north and upstream of the Yangtze River in early August. The upper reaches of the Yangtze River may still increase in flood conditions and cause major floods.

Before that, as an important part of the Yangtze River flood control system, the Three Gorges Reservoir has started flood control work. On June 29, the Three Gorges Dam opened its flood gates for the first time this year to free up storage capacity to meet the possible floods in the near future. On July 2,”Yangtze River Flood No. 1 in 2020″ flowed into the Three Gorges Reservoir. At 14 o’clock that day, there was a peak flow of 53,000 cubic meters per second. After interception, the peak cut rate reached 30%. Cheng Xiaotao believes that Hongfeng No. 1 on the Yangtze River has reached the critical point of 50,000 cubic meters per second. After interception, the downstream safety will be greater.

Zhou Jianjun does not deny the role of the Three Gorges Project in flood control of the main stream of the Yangtze River, but he believes that from the water situation on the 2nd day, there is no safety problem downstream, The Three Gorges should not stop floods.

“The Three Gorges are used to prevent the Jingjiang River from flooding and prevent possible devastating disasters.” Zhou Jianjun believes that according to the Three Gorges flood control plan, the upstream water flow is low At 56700 cubic meters per second, the Three Gorges Reservoir does not need to be intercepted, and discharges directly according to the incoming water flow. Over 56700 cubic meters per second, the Three Gorges Reservoir can start flood storage. He believes that the”Yangtze River No. 1 Flood” did not reach the standard. Such small and medium-sized floods should not be blocked by the Three Gorges at all. As long as the flood control standards and requirements are met in the middle and lower reaches, the floods can be resolved without particularly serious consequences. .

Zhou Jianjun once undertook scientific research projects such as sediment, flood control, ecological environment, dispatching operation and flood control of the Three Gorges Project. He has repeatedly called for safe floods in the middle and lower reaches of the Yangtze River to operate in accordance with the standards of the Three Gorges Plan. But in his view, the reality is,”In these years, we have very high requirements in the construction of water conservancy projects. We must raise the flood control standards to more than one hundred years or even more than one thousand years. Both are eliminated. Not only can the flood control target not be achieved, but also the river ecology is greatly damaged.”

Zhou Jianjun believes that this situation is caused by some middle and lower reaches. The city does not understand professional knowledge. A popular concept is that the Three Gorges interception of small and medium floods can reduce the local flood control pressure, resulting in local over-reliance on the Three Gorges Reservoir. In addition, the Three Gorges intercepting small and medium floods can ensure the economic benefits of dam power generation.

However, the storage of small and medium floods will occupy the flood storage capacity of the Three Gorges.”Whether the floods in the whole basin will come, no one is sure. If you really encounter the kind of big flood of 1954, the current flood storage capacity of the Three Gorges is very stretched.” Zhou Jianjun said.

In addition, he reminded that blocking small and medium floods throughout the year will not only increase the risk of flood control in the Three Gorges, but because the middle and lower reaches have not been flooded for a long time, the river will shrink and further Increase the risk of flood discharge. In the high water level of the dike of the Yangtze River, 4 to 5 meters of dikes have not been exposed to water for a long time. They need to go through safe flooding to allow the dikes to withstand certain tests and timely find hidden dangers and repair them in time. This is an effect that cannot be achieved by instrument detection. The so-called safe flood is the flood that is close to the design flow, often passing this kind of flood can guarantee the flood discharge capacity of the river.

Zheng Shouren, an academician of the Chinese Academy of Engineering and the general director of the Three Gorges Project Design, also said that the discharge of small and medium-sized floods will be less than 45,000 cubic meters per second during the flood season each year. It may lead to the shrinkage and degradation of the middle and lower reaches of the flood channel. If conditions are met, a discharge of 55,000 cubic meters per second should be taken at intervals of several years to comprehensively test the embankment and flood discharge capacity of the Jingjiang reach to prevent the channel from shrinking.

In Zheng Shouren’s view, the Three Gorges Reservoir is not unconditional in blocking small and medium floods. In order to avoid the risk of flood control, the Three Gorges Project must be used to store small and medium floods, and three principles must be followed:First, the Three Gorges Reservoir is required to store small and medium floods to reduce disaster relief; Second, based on real-time rain conditions and forecasting, the Three Gorges Reservoir does not need to implement the Jingjiang or the city. The flood control compensation dispatch will be carried out in the Lingji area; the third is not to reduce the established flood control effect of the Three Gorges Project on the Jingjiang area and ensure the safety of the hub. Only when these conditions are met can the Three Gorges Project be able to activate the storage and storage function.

In Cheng Xiaotao’s view, different scholars will have different views, which is normal. But the factors to be considered in the Three Gorges flood control are many, not just the reference flow.”Complexity also depends on one reason. The Yangtze River still has the problem of bank collapse. The levee basically depends on the Yangtze River. In case of bank collapse, even if the water level is not so high, it will threaten the safety of the levee.”

Therefore, Cheng Xiaotao believes that sometimes other factors such as flow rate may be considered, not just an indicator of flow rate. He agrees that too much interception of small and medium floods and smoothing out all of them will indeed cause the above problems.”The key is one degree.”

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Fragile”last insurance”

In the early morning of July 13, Jiangxi Province’s Flood Control and Drought Relief Command The Ministry issued an emergency notice requesting that all single dike polder dikes in the Lake District must be opened on July 13 to clear the weir and flood storage.

Chen Yunxiang, director of the Jiangxi Provincial River and Lake Management Bureau, told the media that the water level of the Poyang Lake area and the five rivers exceeded the warning water level, and the water level at Xingzi Station even exceeded The historical extreme value and the flood control situation are more severe than in previous years. This year, measures were taken to clear the weir and store floods of all 185 single-retreat dikes.

Flood storage and detention areas are the”actively affected areas” that the country has to demarcate to protect key areas from flooding. Most of them are depressions and lakes. In the 1950s and 1960s, when rivers lacked dams, they shared the pressure on the river. Flood control in the middle and lower reaches of the Yangtze River is mainly achieved through three systems:dikes, flood storage and detention areas, and reservoir groups. Embankments are fundamental. However, in the face of major floods or excessive floods, reservoir peak cuts and flood storage and detention are required to distinguish flood digestion. At present, there are 42 flood storage and detention areas in the main stream of the middle and lower reaches of the Yangtze River, with a total area of ​​about 12,000 square kilometers and an effective flood storage volume of 58.97 billion cubic meters.

Flood storage and detention areas are the”last insurance” in the flood control system. For a long time, they have always been the weakest link. Zhou Jianjun noted that according to the Three Gorges plan, there are currently nearly 28 billion cubic meters of flood storage capacity in the vicinity of the Yangtze River’s Lingji.

In 2016, Shen Huazhong, deputy director of the Flood Control and Drought Relief Office of the Yangtze River Commission, told the media that the middle and lower reaches of the Yangtze River are subject to the requirements of the State Council [1999] No. 12 document. Approximately 10 billion cubic meters of flood storage and detention areas should be built near Chenglingji, and 22.6 billion to 29.8 billion cubic meters of important and general flood storage and detention areas including Chenglingji, Wuhan and Hukou areas should also be built. . The construction of important flood storage and detention areas was originally planned to be completed by 2020, but due to inadequate investment, the progress was obviously lagging behind.

Existing flood storage and detention areas also have long-term management problems. At the end of August 2016, after the flood disaster in Anhui, Cheng Xiaotao, as the former executive deputy director of the Technical Research Center for Flood Control, Drought Relief, and Mitigation of the Ministry of Water Resources, led a team to investigate the severely affected areas. He noticed that after 1999, there were no major floods in the local area for 17 years. The flood prevention awareness of the people in the polder area was weak. The construction of the polder and the construction of new polders occupied the flood channel and the storage capacity of the lake.”The water system of rivers and lakes is crowded and blocked, and the drainage capacity of tributary rivers and the flood storage capacity of the inner lake are reduced, which was an important reason for the severe floods and disasters in the Huwei area of ​​Anhui Province.” Cheng Xiaotao said.

Many flood storage and detention areas have long been reclaimed into fields by the people. After the 1998 flood, the state called for returning farmland to the lake, which was divided into”single retreat” and”double retreat”.”Single retreat” means that the land is not reclaimed, the people move out of the polder area, and the land can be cultivated, but flood gates should be opened during the flood period.”Double retreat” is to retreat people from the fields and restore the natural flood storage capacity of flood storage and detention areas.

In the disaster-stricken area, Cheng Xiaotao found that many”double retreat” became”single retreat”, even in the”single retreat” area, when encountering floods At that time, none of the gates was opened, and the policy was difficult to advance.”The common people think that my place did not collapse during the flood in 1998 (the dam). As long as you persist, you can keep it. Why do you need to open the gate to release the water?”

” The same polder area is now flooded differently than in the past.” Cheng Xiaotao explained that in the past a polder area was flooded, which contained a few acres of land, lost one season of crops, the government has relief, civil affairs has insurance, and social donations, ordinary people can Soon, production will be resumed and homes will be rebuilt. However, now that the young and strong laborers have left the countryside, the land has begun to be intensively operated, and the initial investment in planting or breeding is very large. Once the disaster occurs, the losses are in the order of hundreds of thousands or even tens of millions, and it is difficult for civil relief and agricultural insurance to help these people get through Hardship.

Furthermore, the compensation methods for flood diversion and storage areas are also prone to wrangling.”Nuclear disasters first require nuclear capital and nuclear production. At the beginning of the year, the crops were not yet produced. After the flood, the government proposed to compensate for crops such as rice, but the people said that the crops are grown here as the yield is higher. Therefore, compensation methods for flood storage areas can no longer be done in accordance with the regulations of 20 years ago, and must be adjusted.” Cheng Xiaotao told China News Weekly.

Dr. Yaowei of the Water Conservancy Planning Institute of the Yangtze River Survey, Planning and Design Research Institute wrote:The flood storage and detention area lacks a strict management system. Due to the low compensation standards for resettlement and the relocation of the people Due to problems such as weak willingness, it is difficult to control the population and economic development of flood storage and detention areas, and it is difficult to meet the requirements of”dividing into, storing, and withdrawing”. Once the flood distribution operation has huge losses, it is difficult to use it when flood distribution is needed.

Zhou Jianjun once counted that there are more than 50 million agricultural populations in such areas of the country with poor conditions and high security risks. This is also an important shortcoming to achieve a comprehensive well-off this year.

In 2016, when the flood situation was severe, Anhui also had a place to actively enter the flood. In the”Report on the Investigation of Flood Disasters in the 2016 Yangtze River Basin in Anhui Province” completed by the team of Cheng Xiaotao, it was mentioned that in the flood control and flood control of Anhui, four active flood dikes have played the role of flood protection and embankment, but compared with 129 The number of dikes on the dike and the number of dikes on the initiative to enter the flood are still small. When the flood waters receded, these places pumped water out, but instead resumed production more quickly.

“We have a discussion with the local government. Everyone thinks that taking the initiative to enter the flood is the long-term solution, but no one will take the initiative to choose this plan.” Cheng Xiaotao told””China News Weekly”, such a long dike in the lower reaches of the Yangtze River, no one wants to be specific about which dike. The reason is that, in the interest of local governments, it is better for local governments to take the initiative in flooding, rather than raising the entire embankment to get more funds from the state.

In Cheng Xiaotao’s view, the construction of an eco-environmentally friendly flood control system is a systematic project that requires the mandatory implementation of regulatory systems and the implementation of local governments’ promotion. There must also be strong support from scientific and technological means. Today, 4 years later, in the face of a new round of floods, these problems are still hidden dangers of the Yangtze River flood control. Once it breaks, the consequences will be more serious than ever.

The short board of the Yangtze River flood control system

This year’s flood season exam Prior to the arrival, on May 28, the Ministry of Water Resources organized the 2020 Yangtze River Flood Control Dispatch Exercise. The flood control operation exercise is based on the Yangtze River flood in 1954. The content involves key decision-making processes such as joint operation of reservoir groups, operation of high water levels of dikes, and use of flood storage and detention areas in the middle and lower reaches. An important goal of the exercise is that it hopes to give full play to the joint dispatching of the upper and middle reaches of the Yangtze River Reservoir with the Three Gorges Reservoir as the core, cooperate with flood storage and detention areas and other engineering applications, and make the best possible efforts to mitigate the loss of floods and floods by rationally tapping the flood control potential of the engineering system.

In fact, after the historic floods in 1998, with the completion of the Three Gorges Project in 2006, the Yangtze River flood control system was continuously strengthened.

The Vice Minister of Water Resources Wei Shanzhong mentioned in the”General Strategy for Flood Control and Disaster Mitigation of the Yangtze River in the New Era” published in February 2017 34000 kilometers. Among them, more than 3,900 kilometers of main levees in the middle and lower reaches of the Yangtze River basically reached the planned flood control standards; in order to ensure the safety of flood control in key areas, 42 flood storage and detention areas that can store excess floods of about 59 billion cubic meters were arranged in the main stream of the middle and lower reaches of the Yangtze River. In the ten years of flood control construction, the middle and lower reaches of the Yangtze River have basically formed a comprehensive flood control and disaster mitigation system based on embankments, the Three Gorges Project as the backbone, other main and tributary reservoirs, flood storage and detention areas, river regulation projects and non-flood control measures.”

However, Wei Shanzhong also pointed out that although the flood control capacity of the middle and lower reaches of the Yangtze River has been greatly improved, there are still many problems in the middle and lower reaches of the flood control, including:The contradiction between the safety discharge of the downstream channel and the large peak height of the Yangtze River flood is still outstanding. Although the Three Gorges Project has a flood storage capacity of 22.15 billion cubic meters, the flood storage capacity is still insufficient compared to the huge excess flood volume in the middle and lower reaches of the Yangtze River. In the case of the 1954 major flood, there will be 34 billion to 40 billion cubic meters of excess flood in the main stream, which needs to be properly arranged.

In addition, the flood control capacity of the tributaries and lakes in the middle and lower reaches is low, especially the levee input is small, and most of them do not reach the standard; after the use of the controlled reservoirs in the Three Gorges and the upper reaches of the Yangtze River, The discharge of”clear water” has led to long-term erosion and silting adjustment of the middle and lower reaches of the main river channel, and the problem of bank collapse in some sections of the river is prominent, endangering the river situation and dyke safety; the management of small and medium-sized rivers and the prevention of mountain flood disasters are still in their infancy; there are many small and dangerous reservoir sites It is also extensive and urgently needs to be removed and reinforced.

In July 2008, the State Council officially approved the”Flood Control Plan for the Yangtze River Basin” (hereinafter referred to as”Planning”). After the”Planning” was approved, large-scale flood control projects were launched in the Yangtze River Basin. However, many experts realized that in 2016, 505.8 million people were affected and 121 people were killed by heavy rains and floods in the middle and lower reaches of the Yangtze River, which revealed that there are still many shortcomings in the Yangtze River flood control system.

Zhong Zhiyu, chief engineer of the Yangtze River Water Conservancy Commission of the Ministry of Water Resources, proposed at the two national conferences in 2019 that the main problems of the current Yangtze River flood control and disaster reduction are:lack of new planning guidance The construction and management of flood storage and detention areas in the middle and lower reaches of the Yangtze River lag behind, the bank collapse of the main stream in the middle and lower reaches of the Yangtze River has intensified, and the flood control and security issues of the Zhoutan civilian embankments in the middle and lower reaches of the Yangtze River are prominent.

“As the Three Gorges and other upper reaches of the Yangtze River are successively built, the flood control situation in the middle and lower reaches of the Yangtze River has undergone new and profound changes.” Zhong Zhiyu pointed out that a systematic analysis is required The shortcomings of the Yangtze River flood control and disaster mitigation, re-examination of the flood control standards of the Yangtze River Basin, redistribution of the flood control system, and formulating forward-looking plans.

Zhong Zhiyu suggested that we should accelerate the adjustment and construction of flood storage and detention areas in the middle and lower reaches of the Yangtze River, strengthen bank collapse control and emergency rescue in the main stream of the middle and lower reaches of the Yangtze River, and introduce them as soon as possible Guiding Opinions on Conservation and Utilization Management of Chaotic Beach Embankments in the Middle and Lower Reaches of the Yangtze River

People can never eliminate the flood. How to coexist with the flood is an eternal topic. Cheng Xiaotao believes that at present, these problems are no longer achieved by simply adjusting the management methods of flood storage and detention areas, but the entire”Flood Control Law” must be adjusted. He admitted that the”Flood Control Law”, formulated in the 90s of the last century, responded to the flood characteristics of traditional agricultural society, and it has been seriously lagging behind and must be revised as soon as possible.