Twenty-eight years ago today, on November 6, 1997 (October 7, 1997 in the lunar calendar), the Three Gorges Project carried out the river closure. On November 6, 1997, the Three Gorges Project, the largest hydropower project in the world, began to carry out the river closure after five years of construction. The river closure is a sign of the successful end of the first phase of the Three Gorges Project and an important turning point in the transition from the input period to the income period of the Three Gorges Project. In addition, after the river closure, the river water will be drained by manually excavated diversion channels, and the navigation mode will undergo major changes. Therefore, the river closure of the Three Gorges Project has attracted attention at home and abroad. The most difficult river closure project in the world is to cut off the main riverbed of the Yangtze River by building two upstream and downstream cofferdams, and then build the power plant and dam on the left bank of the Three Gorges Project on the dry riverbed of the Three Gorges Project. The first batch of power generation units planned for 2003 will be installed here. The closure of the river actually refers to the closure of the dragon mouth of the upstream cofferdam. The closure of the Three Gorges is currently the most difficult closure project in the world's water conservancy projects. The design flow rate selected during the closure of the Three Gorges interception is 14,000 cubic meters to 19,400 cubic meters per second, which is 1.75 times the maximum interception flow of the world hydropower project so far - Brazil Itaipu project; it is the largest interception flow in China - 2.9 times the interception flow of Gezhouba. The maximum water depth of the Three Gorges interception is 60 meters, which is the largest interception water depth of the world hydropower project - 1.3 times the interception water depth of the Dales project in the United States, and 40 meters deeper than the interception water of Gezhouba. Due to the rapid surge of the Three Gorges water, the underwater geological conditions are very complicated. Interception under deep water and large flow conditions, preventing cofferdam collapse and solving the problem of anti-seepage will be the first world-class technical problems faced by the Three Gorges Project since the start of construction. According to Lu Youmei, general manager of China Three Gorges Project Development Corporation, the key technical issues involved in the closure of the Three Gorges have been overcome, and a relatively complete construction plan has been formed. The interception in early November is fully guaranteed both technically and in terms of construction preparations. The interception is advanced during the construction period. Generally speaking, the interception time of hydropower projects should be selected in the dry season with small flow and drop, which can reduce the difficulty of interception. According to hydrological data, the driest flow of the Yangtze River at the Three Gorges Dam site is generally from late January to late February, and the flow during this period is generally only 3,000 cubic meters to 6,000 cubic meters per second. Why should the interception of the Three Gorges be carried out in early November, when the water level is high and there is a possibility of large floods? It is understood that the reason why the closure time is advanced is because the construction period of the second-phase cofferdam is extremely urgent. Considering the requirements of safe flood control, after the closure and closure of the river, the cofferdam must be filled to the elevation required for safe flood control before the arrival of the Yangtze River flood season in May 1998, and a seepage wall with a total area of 72,000 square meters must be built, otherwise catastrophic consequences will occur. After comprehensively analyzing the difficulties involved in the closure, the urgency of cofferdam construction and other factors, and having a full technical grasp of the closure under the condition of large flow, the experts finally determined that the closure time of the Three Gorges closure was set in early November. The time for the closure of the Three Gorges River was chosen in November, just after the flood season of the Yangtze River. During this period, the water level of the Yangtze River changed greatly. The actual water volume and water depth of the closure cannot be completely determined. For example, in early November 1996, there was a flood of 26,400 cubic meters per second at the site of the Three Gorges Dam. If this happens, the closure will be more difficult. The reporter learned from the Three Gorges construction site that the relevant units have been prepared to face various harsh conditions and fight a hard battle. The closure construction is divided into three stages. The construction of the Three Gorges closure is carried out in three stages. The first stage is the "pre-occupation" stage of the cofferdam, that is, it is divided into 4 embankments on the main river of the Yangtze River in advance, and the upstream and downstream cofferdams are pushed towards the center of the river, so that the upper and lower cofferdams only leave 460 meters and 480 meters wide at the entrance of the river respectively. At the same time, a large number of stones are thrown at the bottom of the river at the entrance to raise the deep channel of the riverbed, reducing the water depth from 60 meters to more than 20 meters. The first phase of construction started in November 1996, and by April 1997, the construction target had been fully completed; the second phase of construction started from the beginning of September 1997 to November 3, 1997, and the upstream cofferdam where the interception is located was narrowed from 460 meters to 130 meters wide, forming the interception dragon mouth; the third stage is the interception of the dragon. It is planned that one day in the middle of November 6 to 8, according to the meteorological and hydrological conditions, the final sprint of the cross-locking Yangtze River will be launched. According to experts' estimates, the 130-meter dragon mouth needs 210,000 cubic meters of soil and stone to be blocked. 70,000 cubic meters of soil and stone are thrown daily on the narrow cofferdam embankment for 3 consecutive days. Such a high construction intensity is also rare in the history of water conservancy construction in the world. According to the introduction, when the closure is closed, soil and stone will be thrown at the four embankments of the upstream and downstream cofferdams at the same time, of which the largest block weight is 3 tons to 5 tons. According to the closure construction plan, the upstream cofferdam Longkou will be locked first, and the downstream cofferdam will be followed by the closure. By the beginning of October, the entrance of the Three Gorges closure cofferdam in the middle of the river is only 360 meters wide, and it is advancing towards the river at a rate of about 4 meters per day. The construction of the Three Gorges closure and the second phase of the cofferdam is selected by inviting tenders. The Gezhouba group company, which once built the first dam of the Wanli Yangtze River on the Yangtze River, has undertaken the arduous task of the Three Gorges closure and cofferdam construction. At present, Gezhouba group company is mobilizing all kinds of large-scale modern construction equipment, and the interception and stocking have been completed 10 million cubic meters, which is 3 million cubic meters more than predicted. The interception and continuous navigation of the Yangtze River is the golden waterway of our country. To build the Three Gorges Dam on the Yangtze River, it is necessary to ensure the smooth navigation of the Yangtze River during the construction period. Whether it can ensure normal navigation is the key to whether the Three Gorges can intercept. In January 1981, after the interception of the Gezhouba Dam project, the Yangtze River in this area was cut off for about half a year. The design of the Three Gorges Project has fully considered the shipping problem. In order to solve the navigation problem, the Three Gorges Project decided to adopt the navigation plan of diversion open channel combined with temporary ship lock. Therefore, the diversion nullah and temporary locks have become a control project for whether the Three Gorges can be closed as scheduled. The diversion nullah is located on the south bank of the Yangtze River, with a total length of 3,726 meters, a bottom width of about 350 meters, and a bottom elevation of 58 meters. Its river width and depth are larger than those of the world-famous Suez Canal and the Panama Canal. The nullah section adopts a duplex section, which can better adjust the flow rate distribution in the nullah. It must ensure the safe venting of the Yangtze River flood once in 50 years (the flow rate is 79,000 cubic meters per second). When the flow of the Yangtze River is less than 20,000 cubic meters per second, ships pass through the nullah. It is estimated that an average of 272 days can be passed through the nullah in a year. After the hard work of the builders, the diversion nullah has broken the weir and flooded on May 1, 1997, one month ahead of the contract construction period. At 9 am on October 6, the diversion channel was officially put into operation. The main riverbed of the Yangtze River at the site of the Three Gorges Dam was closed to traffic, and ships passed smoothly through this "man-made Yangtze River". At 3:30 pm on November 8, with the last load of stones pouring into the river, the world-renowned Three Gorges Project successfully achieved the closure of the river. Compared with other hydropower projects, the river closure of the Three Gorges Project is the most difficult. It is to build the Three Gorges Dam and the power station building by building two cofferdams on the main riverbed of the Yangtze River. The Three Gorges Project can be called a world-class mega-project due to its large scale, large installed hydropower capacity and significant comprehensive benefits. This "battle of the century" that traverses the Yangtze River began in November 1996. As of November 8, after the hard work of the builders of the Three Gorges, only 40 meters of Xiaolongkou remained in the upstream interception cofferdam. At 9 am, Premier Li Peng officially issued the order to close the dragon at the construction site near Longkou. Three signal flares fired by the deputy commander on site rose into the air. In an instant, the vehicles on the four embankments of the upstream and downstream cofferdams were ready to go like a group of mighty lions, approaching the galloping Longkou of the river. Zhu Xianqing, a team of drivers from a company of Gezhouba Group, took the lead in driving a dump truck and threw the first truck of stones at Longkou. More than 400 giant loading vehicles took turns to throw stones at Longkou in a tense and orderly manner at the four embankments of the upstream and downstream cofferdams, causing waves and making a huge noise. The Longkou was gradually narrowed to 30 meters, 20 meters, 10 meters, 5 meters... The closure site of the Dagang River was full of grand and warm atmosphere. The huge five-star red flag with an area of 1080 square meters spliced with woven carpets on the viewing platform was particularly spectacular. 30,000 potted flowers and colorful balloons dressed up the closure ceremony site. The colorful flags of the dam site fluttered, and the huge balloons were hung with slogans congratulating the successful closure and closure of the dragon. At 3:00 pm, the closure ceremony of the Dagang River began, and the majestic national anthem echoed in the canyon. Lu Youmei, general manager of the Three Gorges Engineering Development Corporation, reported the progress of the Three Gorges Project to the representatives from all walks of life who attended the ceremony. At 3:30 pm, the upstream cofferdam was successfully intercepted, and the left and right embankments were completely connected together. Upstream of Gezhouba group company, the commander-in-chief of the left bank and the commander-in-chief of the right bank crossed the hulong and hugged each other tightly. Cheers and cheers resounded through the clouds. Premier Li Peng announced the success of the interception, and then three signal flares cut through the sky. At this moment, more than 1,000 construction troops at the interception site, more than 5,000 guests and more than 40,000 local cadres, immigrants and tourists on both sides of the strait were jubilant. Firecrackers blared in unison, cars and boats honked their horns and horns, and people cheered enthusiastically, like a thick symphony that echoed the earth at the Three Gorges construction site. Colorful balloons flew into the sky, and the interception site formed a sea of joy. Jiang Zemin, Li Peng and other leaders attended the interception ceremony.