Climate is the main factor affecting the prosperous summer of the Yangtze River Basin

□ Changjiang Daily reporter Yang Jiafeng

Most of the regions of the Yangtze River Basin are located in the south of my country. The water resources are relatively abundant, but this year is particularly abnormal. According to meteorological predictions, the drought conditions of the Yangtze River Basin may continue to develop.

Information released by the Ministry of Water Conservancy on the 17th: The smallest precipitation in the Yangtze River Basin has been the least in 60 years; the water level in the upper reaches of the Yangtze River is the least; The appearance of withered water is the earliest dead water level since 1951.

Chen Jin, professor of lectures in Wuhan University, and the Deputy Director of the Water Resources Professional Committee of the China Water Conservancy Society, analyzed that in history, the phenomenon of the Yangtze River has also appeared, such as this year in 1978 and 2006. The probability of summer and autumn drought in the Yangtze River Basin is the largest, and the severe drought cycle is about 20 years or so. This year's special is that the duration of high temperature weather is long, which increases the effects of drought. This is rare. The following is the conversation of Chen Jin, a reporter from the Yangtze River Daily--

Reporter: This year, what are the main factors that affect the midsummer of the Yangtze River Basin? Is it the cause of the climate or the environmental change?

Chen Jin: The main factors that affect the midsummer of the Yangtze River Basin are obviously the cause of the climate. The drought of the Yangtze River Basin has periodic characteristics. According to the historical data statistics of the 15th century to the 20th century, the an average of 7-8 years on average of heavy drought or above in the Yangtze River Basin. Among them Once once, and about 65 years of upstream. For more than 70 years after the founding of New China, the year of heavy drought and extremely drought was 1959, 1978, 2006, and 2011. From the point of view of the occurrence, the most common is summer and autumn, followed by drought in spring and summer. The traditional arid and watery areas of the Yangtze River Basin are mainly in Sichuan Basin, Central Yunnan, Central Dian, Central Guizhou, Hunan Hengshao area, Jiangxi Jiangnan area, Tang Baihe area in the Han River, and north of Hubei.

This year's drought cause is mainly affected by the periodic La Nina phenomenon. Since the summer of the northern hemisphere of the earth, the atmospheric circulation is abnormal. In the middle and lower reaches, it is caused by comprehensive factors such as typhoons.

Reporter: On August 17th, the Ministry of Water Conservancy held a press conference on the relevant situation of the Yangtze River Basin to keep drought -protection and protect the water harvest. "The lowest time in the same period", how do you understand this sentence?

Chen Jin: The hydrological sites of the Yangtze River and the two lakes are established. The earliest Hankou Station was established in 1865. Other sites are late. The measured materials for Dongting Lake and Poyang Lake have been established since the establishment of New China, and it is estimated that it has only been 60 to 70 years. Another word "same period" refers to the historically August 17th, which does not represent other dates. If the history refers to a certain day, the problem is not serious. If the average history of the average water level in a month or the entire flood season is the lowest, the problem is serious.

Reporter: In the past, the water level of Poyang Lake and Dongting Lake often declined sharply in winter, but this year was in midsummer. Why did this situation form this situation? What is the main reason?

Chen Jin: The main reason is that since the beginning of the summer, the rainfall in the Yangtze River, Poyang Lake, and Dongting Lake Basin has decreased significantly compared to usual. According to statistics from the National Climate Center and the Ministry of Water Resources: In July, it came to August 15th. The rainfall of the Yangtze River Basin was 40 % less than that of the year, and the rivers and rivers were less than 20 % to 80 %. The main hydrological stations in the Yangtze River are much lower than that of the year. Poyang Lake's terrain is higher than the Yangtze River. The Wuliang (Gan, Fu, Xin, Rao, and Xiu) of the Poyang Lake Basin generally accounts for 85%of Poyang Lake's flow. So Poyang Lake enters the dry period in advance. The waters of Dongting Lake include the three rivers of the three sidelines of Si Shui (Xiang, Zi, 沅, 澧) and the Jingnan of the Yangtze River. These rivers are relatively small, so Dongting Lake also enters the water level after the Poyang Lake.

Reporter: There are large water conservancy projects including the Three Gorges Dam and Gezhou Dam along the Yangtze River. How does this year play a regulatory role? What are the characteristics of water circulation in the Yangtze River Basin?

Chen Jin: There is a deviation in this problem. Gezhouba has no adjustment capacity. It is a daily regulating reservoir and has no ability to replenish downstream. Although the Three Gorges Reservoir Reservoir is large, it is a quarterly regulating reservoir, which mainly increases the water volume in the middle and lower reaches of the Yangtze River (December to May of the following year). In the flood season (June to September) The main purpose is to adjust the flood. At present, the water level of the Three Gorges Reservoir is about 146 to 147 meters. There is not much amount of surplus water increased. The amount of large reservoir in the upstream of the upstream of the Yangtze River is basically the same. However, even so, the upstream reservoir group in the Yangtze River is still exerting potential to replenish drought to the middle and lower reaches.

The water circulation characteristics of the Yangtze River Basin are the synchronization of water heat. Generally, there are many rainstorms and floods in summer, less rainfall and less runoff in the dry seasons. In this period, the upstream reservoir group can sustainly increase the flow of the lower leakage and replenish downstream. This year is a typical drought year, the climate is abnormal, the rainy period in summer is short, and there are no typhoons to go deep into the Mainland.

【Edit: Bian Liqun】

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