Why does the Yangtze River Basin "fall off the flood season"?

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The drought in the Yangtze River Basin this year

Mainly related to atmospheric circulation

"It didn't rain for almost a month, and the water in Wuchahe was bottomed out." Wu Tong (a pseudonym) in his 30s looked at more than 40 acres of rice facing the water shortage and couldn't help anxious.

The Wucha River is one of the drainage channels in Jiangling County, Jingzhou City, Hubei Province, and a small and medium river in the Yangtze River Basin. In the memory of some villagers in Shagang Town, at this time in the flood season at this time, the government often called on villagers to participate in the flood prevention work. Whoever thinks, this year's flood season is so serious.

Including Jingzhou, Hubei, since July, under the control of the subtropical high pressure, the water level of the Yangtze River has continued to decline after entering the main flood season, and a rare phenomenon of "anti -dead during the flood season" has occurred. Right now, the high temperature and drought in the Yangtze River Basin are still continuing, and agricultural production and mass drinking water in many regions such as Anhui, Jiangxi, Hubei and other provinces are affected.

Xu Jijun, director of the Institute of Water Resources of the Yangtze River Academy of Sciences, told China News Weekly that the drought is wide, the duration of high temperature and drought is long, and the degree of drought is serious. This is the main feature of the drought in the Yangtze River Basin this year. He recalled that in the past few decades, the Yangtze River Basin has also experienced drought during the flood season, but it has not involved the upper, middle and lower reaches of the Yangtze River as this year, and has a serious impact.

Some rice fields appear in some rice fields. Source: Provided by the respondents

3.4 million people are affected by water supply

In early July this year, the heavy rain invaded Jiangling County, Jingzhou. The rainwater continued a month before, and Wu Tong remembered that the river was almost crossing the river embankment. He was worried that this year's flood situation will be severe compared with previous years, which will affect the quality of crayfish and will also affect subsequent rice sowing.

However, after this heavy rain in July, it came to a large range of high temperature and drought. Different from floods, the impact of this weather appears step by step.

First, the heat wave brought to the body's discomfort. The highest temperature in the local area exceeded 35 ° C for many days, and it seemed to have entered the steamer. Wu fishes a few hours of fish by the river. After returning home, his mouth was dry, and his head was dizzy. He speculated that he might be a heat stroke. If the air conditioner is not turned on at night, people cannot sleep.

After entering August, the drought is getting more and more obvious. The new river near Wu Tong's family was originally two or three meters deep. These days, the river water slowly became lighter until the river bed was exposed, and the fish and shrimp were gone. When it comes to three or four centimeters, some strong ears of rice appear, and there are more pests.

On August 19, Wu Tong discovered that the soybeans in a few acres of land were almost dead, and most of the pods were opened, most of which were ravioli. He was annoyed. It's all cut. "

According to the news released by Jiangling County official on August 15, the county appeared in the county's continuous high temperature and hot weather. The amount of water and evaporation of farmland intensified the amount of water and evaporation. About 450,000 acres of farmland were drought in each township management area, and the drought resistance was severe.

On August 23, the largest freshwater lake in Poyang Lake, Poyang Lake, China, Jinxi Lake Water Picture/Zhongxin Picture Network

This is also a problem faced by many areas in the Yangtze River Basin. In Nanchong, Sichuan, the grapes of a orchard were roasted into raisins with a loss of 300,000 yuan. In the area of ​​the Qianxiangmen Bridge of Jialingjiang, Chongqing, large beaches were exposed to the water surface. The residents nearby said that this is a rare situation for decades; In the territory, there are 6 rivers with an area of ​​more than 200 square kilometers in the basin area. 6 have been broken; Jiangxi Lake mouth, the water body area of ​​Poyang Lake, which was originally Bibo, "shrinks". According to Suiyang County, Guizhou, 500 acres of orchards are short of water. The person in charge had to ask for help and use multi -functional water guns to water in the form of spray water.

The Ministry of Water Conservancy said the most serious weather drought in the Yangtze River Basin since 1961. Since July, the rainfall of the Yangtze River Basin is 40 % less than the same period of the same year. At present, the water level of the Yangtze River and Dongting Lake and Poyang Lake is 4.85 to 6.13 meters lower than the same period of the year.

According to official news, as of August 22, the arable land in 10 provinces and cities in the Yangtze River Basin was 48.48 million mu, with 3.4 million people and 580,000 large livestock affected due to drought supply. Anhui, Jiangxi, Jiangsu and other places.

The upstream reservoir group "water replenishment" 1.96 billion cubic meters

On August 11, the Ministry of Water Resources launched a grade IV emergency response to the six provinces (municipalities) in Anhui and Jiangxi, and fully resisted the rapid development of drought in the Yangtze River Basin.

At 12 o'clock on the 16th, the Ministry of Water Resources began to implement the "Special Action for Drought Restrictions on Drought Protection and Water Supply for Reservoir Group in the Yangtze River Basin". According to Xinhua News Agency on the 24th, a total of 1.96 billion cubic meters of water replenishing the upstream reservoir group, the Dongting Lake Water System Reservoir Group and the Poyang Lake Water System Reservoir have accumulated a total of 1.96 billion cubic meters.

Xu Jijun said that in the absence of artificial rainfall conditions, relying on reservoir dispatching and supply and water supply irrigation became the main way to resist drought resistance. There are 50,000 reservoirs in the Yangtze River Basin, and some large reservoirs such as the Three Gorges and Danjiangkou can ensure water supply and irrigation needs to a certain extent. At the same time, other water conservancy projects in the basin, including some local weir and ponds, also exerted important water supply and irrigation water demand.

It is worth noting that Xu Jijun also mentioned that the reservoir usually follows the existing scheduling procedures. Before the flood season, that is, from April to May, the reservoir increased the flow of the underwater level to reduce the water level from the waters to the flood level. Originally, I was preparing to make floods, but I did not expect that the flood did not come, but there were rare high temperature droughts, and severe precipitation occurred on the upper and middle and lower reaches of the Yangtze River this year. limited. In the face of such a serious drought, how scientific and fine reservoirs are scientific and fine to ensure water supply and irrigation needs, and there are certain difficulties. At present, many small reservoirs and weir ponds in the Yangtze River Basin have dried up, and large and medium -sized reservoirs still have a certain amount of water.

For the current continuous development of drought, especially the critical period of crop growth in the next week is the most important period for crop irrigation. Digital simulation rehearsal in the reservoir group of the upstream reservoir group in Dongting Lake, the diversion facilities of the downstream, and the demand for water use, the digital simulation preview, accurately calculate the flow, water level, and water volume of the downstream local area, and scientifically formulate drought resistance scheduling schemes.

On August 19, a river section was dry before and after a river section in Jiangling County, Jingzhou City, Hubei Province. Photo/Interviewee provided

Around August 20, Wu Tong discovered that the dry Wucha River began to return to the water for many days. At about seven in the morning, while the high temperature did not start, he pulled the pump and led the water into some rice fields.

The current water flow can still be obviously unable to meet the needs of all farmland. Not long ago, some villagers began to contact the well team and tried to find groundwater to relieve drought. However, Wu Tong found that now he has to line up. "Many people make an appointment, the master is too busy."

This is exactly the drought -proof measures carried out in many places such as Tongshan and Huangshan, Anhui. In some areas, farmers picked water through manpower and tried to keep water -lacking crops.

"Now the most worried about autumn, especially in September. If the next rain can be rained at the end of August, this year's drought can be relieved." Xu Jijun said that the current effects of the drought in the Yangtze River Basin are mainly reflected in agricultural production. The drought area is large, especially the growth of rice and late rice is in a critical period. High temperature drought is not good for its autumn grain harvest. At present, it is urgent to ensure irrigation needs. In terms of people drinking, there are difficulties in the mountains or rural areas inside the Yangtze River Basin. At present, the water conservancy department is strengthening water supply protection at all levels to reduce the adverse effects of drought. If there is a phenomenon of drought in summer and autumn, the situation of drought resistance will be more severe.

On August 22, the Yangtze River Defense Federation analyzed that according to hydrological and meteorological predictions, on the 23rd, the Yangtze River Basin basically had no rainfall process; from 24th to 25th, there was a medium rain in the upper reaches of the Jialing River and above Hanjiang Shiquan. Dark rain and local area heavy rain; from the 27th to 28th, there were heavy rain and rainfall in the upper reaches of the Jiayu Basin and the upper reaches of the Han River.

The meeting also pointed out that the current drought situation of the basin is still continuously developing, but there will be an obvious rainfall process around the 26th. It is necessary to pay close attention to the trend of water conditions and rain in the basin, strengthen risk research and forecast early warning, do a good job of drought and flood urgency. Transfer to the control of the mountain flood disasters to prevent response, so that the flood prevention and drought resistance should be grasped.

Extreme weather is frequent, how to deal with drought problems in the future

Many meteorological and water conservancy experts said that the drought in the Yangtze River Basin this year is mainly related to the atmospheric circulation.

In Xu Jijun's view, the dry scope of dryness, long and drought duration of high temperatures, and a serious degree of drought. This is the main feature of the drought in the Yangtze River Basin this year. He recalled that in the past few decades, the Yangtze River Basin has also experienced drought during the flood season, but it has not involved the upper, middle and lower reaches of the Yangtze River as this year, and has a serious impact.

"Since June, precipitation in the Yangtze River Basin has occurred less than usual. This year's rainstorm period is short, and the typhoon has not affected this area. Entering July, the precipitation is 40%-50 less than usual year. %, More than 60%of the local areas, "Xu Jijun told China News Weekly. At the same time, high temperatures in most parts of the basin continued to retreat. God, these factors have led to the rapid development of the drought in the Yangtze River Basin.

According to the monitoring results of the National Climate Center, since July, the rainfall of the Yangtze River Basin has been 40 % less than the same period of the same year. The Poyang Lake and the Jialing River Basin are 50 % to 70 %, and there are no effective rainfall days in some areas for more than 20 days. In July, the precipitation distance of the Yangtze River Basin was basically above -50%; but by August, the precipitation distance in the eastern area of ​​the Yangtze River Basin was less than -80%, and the precipitation of the entire Yangtze River Basin was less than 50mm. It is even less than 1mm.

On August 23, a large piece of weeds grown in Jinxi Lake in Jinxian County, Poyang Lake District, Jiangxi, became the natural pasture of cattle. Figure/Zhongxin Picture Network

On August 18, the Central Meteorological Observatory issued the first meteorological drought yellow warning this year. The National Climate Center said that the comprehensive intensity of regional high -temperature events since June 13 this year has reached the strongest meteorological observation record in 1961 (official news of the National Climate Center). Since the summer (June 1st to August 15th), the average number of high temperatures in the country is 12.0 days, which is 5.1 days more than the same period of the year. It is the same period since the complete meteorological observation records in 1961. A total of 914 national meteorological stations in the country reached the standard of extreme high temperature events, and the maximum temperature of 262 national meteorological stations was flat or broke through the historical pole value. Drought is also related to the trend of global warming. In an interview with the media, the director of the National Climate Center mentioned that in the context of global warming, the frequency and intensity of extreme weather and climate events increased, including land and marine extreme high temperatures, heavy precipitation events, droughts and fire weather It caused serious interference and destruction to the order of social production and life, and caused a large number of casualties and property losses.

In response to the drought conditions of the Yangtze River Basin, which are still continuously developing, experts from the China Institute of Water Resources and Hydropower Sciences said that it is recommended to strengthen the unified management and scientific configuration of existing drought -resistant water sources in the region, make overall arrangements, ensure the key points, and make the limited water source play the greatest drought resistance to drought resistance. Benefits; supervise and guide the discharge of the difficulty of drinking water in the dry area, and adopt emergency measures such as extended pipeline networks, setting up temporary water extraction points, and organizing social forces to pull water and sending water according to local conditions to fully protect the demand for living water for the masses.

In the long run, in the context of global warming and extreme weather increase, how to improve drought and disaster defense adaptability is also a matter of attention.

Regarding the drought disasters of the Yangtze River Basin, Xu Jijun said that first of all, the overall planning of flood control and drought resistance to strengthen the overall defense capabilities of water and drought disasters. "Flood prevention and drought resistance. You need to do a good job at the level of research and planning. "

In response to the problems of the flood season of the reservoir, according to the improvement of the forecast level, through in -depth research and analysis, especially for some reservoirs with large water supply and irrigation tasks, the scheduling regulations can be appropriately adjusted, and the flood limit water level can be implemented. Under the premise of ensuring flood prevention, leave as much water storage as much as possible to deal with high temperature drought.

Xu Jijun believes that the construction of drought monitoring and evaluation and forecasting early warning system must be strengthened. "Our flood monitoring and flood prevention system is better, but in drought resistance, monitoring and early warning technology and system platform construction, it is still weak, and it needs to be strengthened."

Secondly, the construction of drought resistance in the Yangtze River Basin must be improved. For example, on the basis of existing projects, drought -resistant projects such as emergency water sources, cited water projects and spare underground water storage facilities are supplemented to better cope with possible drought problems. In addition, the response and defense of extreme droughts caused by climate change must be done well, and emergency plans for extreme drought incidents. "Climate change has caused the time and space distribution of precipitation in the Yangtze River Basin to mutation, and the increase in extreme precipitation and extreme drought incidents is more harmful than before. This is what it needs to pay attention to in the future."

Author: Wang Chunxiao ([email protected])

Edit: Li Zhiquan

Operation editor: Wang Lin

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