China News Service, August 19, according to the website of the Ministry of Water Resources, from August 11-17, two successive heavy rainfall processes occurred in the Jiamin Basin on the upper reaches of the Yangtze River. Affected by heavy rainfall, it is expected that on August 19 and 20, the Cuntan and Three Gorges Reservoir on the upper reaches of the Yangtze River will have a peak discharge of about 74,000 cubic meters per second respectively, which is the largest flood since 1981 and the largest since the construction of the Three Gorges Reservoir. Reservoir floods, it is estimated that the inflow of the Three Gorges Reservoir will exceed 50,000 cubic meters per second for a duration of 5 days. In consultation with the Ministry of Water Resources, the response to the No. 5 flood of the Yangtze River was further arranged and deployed, and the discharge flow of the Three Gorges was adjusted in a timely manner to reduce the pressure on flood control in the reservoir area and downstream.
Data map: On August 15, Yichang, Hubei, the flood discharge of the Three Gorges Dam ushered in the No. 4 flood of the Yangtze River. The picture shows that river water is discharged through the deep hole of the Three Gorges Dam. Image source: People's Vision
From August 11 to 17, two successive heavy rainfall processes occurred in the Jiamin River Basin in the upper reaches of the Yangtze River. During the process, the rainfall was concentrated, intense, and extreme. The cumulative rainfall was greater than 250 mm and covered an area of 67,000 square kilometers, and the cover was greater than 100 mm. Covering an area of 227,000 square kilometers, the cumulative rainfall at Beichuan Station reached 946 mm. The rainfall, the coverage of the rain area, and the maximum rainfall at a single station all exceeded the rainfall during the same period of the 1981 upstream catastrophic flood.
Affected by heavy rainfall, 51 rivers including the Shigu section of the Jinsha River in the upper reaches of the Yangtze River, the Zhutuo-Cuntan section of the upper mainstream of the Yangtze River, and the main branches of the Minjiang River, Tuojiang River, Jialing River, and Fujiang River experienced over-alarm floods. Over-preservation floods occurred in 29 rivers including the middle and lower reaches of the Minjiang River, Tuojiang River, Fujiang River, the upper reaches of the Jialing River and its tributary Bailong River, and 9 rivers including the main stream of the Minjiang River and its tributaries Qingyi River, the Bailong River in the upper reaches of the Jialing River and the Baishui River tributary, etc., experienced ultra-historical floods. It is estimated that on August 19 and 20, the Cuntan and Three Gorges Reservoir in the upper reaches of the Yangtze River will have a peak discharge of about 74,000 cubic meters per second respectively. Both are the largest floods since 1981 and the largest since the construction of the Three Gorges Reservoir. The inflow of the reservoir will exceed 50,000 cubic meters per second for a duration of 5 days.
Since August 11, E Jingping, deputy commander-in-chief of the State General Defense and Minister of the Ministry of Water Resources, has presided over the flood control consultations six times, and targeted arrangements for the deployment of the Yangtze River flood defense work. On August 18, Ye Jianchun, Vice Minister of the Ministry of Water Resources, hosted two conferences to study and judge the development trend of the Yangtze River flood, and further study and deploy the response to the No. 5 flood of the Yangtze River.
The meeting made further arrangements for the response to the No. 5 Yangtze River flood. One is to further optimize the storage and dispatch of upstream reservoir groups. According to the new rainfall and future forecasts, the Yangtze River Water Resources Commission of the Ministry of Water Resources further excavated cascade reservoirs in the Jinping I and Ertan of the Yalong River, Xiluodu, Xiangjiaba, Wudongde of the Jinsha River, Pubugou of the Dadu River, and Tingzikou of the Jialing River. The group has the potential to intercept floods, optimizes the interception timing, and more accurately intercepts flood peaks. The upstream reservoir group is initially arranged to intercept 3.5 billion cubic meters. After the upstream reservoir group is fully blocked, it is expected that the Cuntan Station will have a peak water level of about 189.3 meters around the evening of the 19th (about 5.8 meters above the guaranteed water level), with a corresponding flow of 74,000 cubic meters per second; the Three Gorges Reservoir will be around the early morning of the 20th There is a maximum inbound flow of about 74,000 cubic meters per second.
The second is to adjust the discharge flow of the Three Gorges in a timely manner to reduce the pressure on flood control in the reservoir area and downstream. On the basis of increasing the discharge flow to 44,000 cubic meters per second on the afternoon of the 17th, dispatch the Three Gorges Reservoir to increase the discharge to 46,000 cubic meters per second and 48,000 cubic meters per second at 12:30 and 17:30 on the 18th. In order to reduce the flood control pressure in the reservoir area, according to analysis and estimation, it is estimated that the highest flood level of the Three Gorges Reservoir on the 22nd is 165.5 meters, and the over-alarm range from the main Liusha city to the Lianhuatang section of the middle reaches is controlled at about 0.3-0.9 meters.
The third is to issue a notice to put forward requirements for flood prevention in the reservoir area. On the afternoon of the 18th, the Ministry of Water Resources issued a notice to the Chongqing Water Conservancy Bureau, requesting resolute implementation of flood prevention responsibilities, strengthening of personnel in the reservoir area, patrol and defense of reservoir banks, strengthening of personnel transfer and avoidance, information sharing and reporting, and making every effort to deal with floods in the Three Gorges reservoir area. Prevent and respond to work to ensure personnel safety. The fourth is to strengthen assistance and guidance. A working group from the Ministry of Water Resources has been dispatched to Chongqing to assist and guide the defense work along the main stream of the Yangtze River and the banks of the Three Gorges Reservoir. The Chongqing Water Resources Bureau has initiated Level I emergency response.