rare!
Affected by the continuous high temperature weather, the main flood season has not yet ended, and drought has already occurred in the Yangtze River Basin, and Dongting Lake and Poyang Lake have entered the dry season ahead of schedule.
As of 8:00 on August 17, the water level of Xingzi Station, the iconic hydrological station of Poyang Lake, was 10.29 meters, which was 6.37 meters lower than the same period of last year.
The Tongjiang water body in the lake area covers an area of 803 square kilometers, a decrease of 2097 square kilometers compared with the same period last year.
severe!
The drought situation in the Yangtze River Basin is developing rapidly. As of August 17, the 6 provinces (cities) of Sichuan, Chongqing, Hubei, Hunan, Jiangxi, and Anhui have been affected by drought with an area of 12.32 million mu of arable land, affecting 830,000 people and 160,000 large livestock water supply.
What are the characteristics of drought in the Yangtze River Basin?
What is the cause of this drought?
In the future, what is the trend of drought in the Yangtze River Basin?
How to fight the tough battle of drought relief and disaster reduction?
The lowest precipitation in the same period in history
Drought could develop further
Talking about the characteristics of this drought, Liu Zhiyu, deputy director of the Information Center of the Ministry of Water Resources, told reporters that first, the precipitation was the least in the same period in history, and there were many days with high temperature and little rain.
Since July, the precipitation in the Yangtze River Basin has been 40% to 50% lower than the same period of the previous year, which is the lowest in the same period in history since 1961.
The number of high-temperature days in most areas of the basin exceeded 20 days, and in the middle and lower reaches of the country for more than 30 days. Among them, there were more than 40 days of continuous rainy days in Hunan.
Second, the inflow of water from rivers is obviously low, and the water level continues to decline.
Since July, the inflow of water from the main and tributaries of the Yangtze River has been 20% to 80% lower than that of the same period of the previous year, and the inflow volume of the upper and middle reaches is the least since 1949.
Dongting Lake and Poyang Lake fell below the low water level on August 4 and 6, respectively, the earliest since 1971 and 1951.
At present, the water surface area of the main stream of the Yangtze River and Dongting Lake and Poyang Lake has decreased by 3/4 compared with that in June.
Most of the Yangtze River Basin is located in the south, and the water resources are relatively abundant. The rainfall is mainly concentrated in the flood season, that is, from April to September.
Why do severe droughts occur?
Liu Zhiyu analyzed that, under normal circumstances, from July to August, the upper reaches of the Yangtze River are located on the west side of the Western Pacific subtropical high, which is a rainy area.
In the context of global warming, affected by the continuous La Niña event, since July this year, the subtropical high pressure in the western Pacific Ocean has been larger in area, stronger in intensity, and located in the west and north. There is little rainfall, and the main rivers and lakes in the basin have significantly less water, resulting in a drought that is rare in the same period for many years.
Will the drought in the Yangtze River Basin continue?
Liu Zhiyu responded that it is expected that before the end of August, the overall precipitation and water inflow in the Yangtze River Basin will still be low. Looking forward to September, the precipitation and water inflow in most parts of the middle and lower reaches may continue to be low, and the drought situation in Anhui, Hubei, Hunan, Jiangxi and other places may still be low. With further development, the water storage situation of the reservoirs in the upper reaches of the Yangtze River is grim.
Reservoir joint dispatch to replenish water in arid areas
Secure water supply and irrigation water
Facing the severe drought situation, since August, the water conservancy department has dispatched the controlled reservoirs in the Yangtze River Basin to supply 5.3 billion cubic meters of water to the middle and lower reaches.
"At present, autumn crops such as rice in the Yangtze River Basin are in a critical period of irrigation water demand. In order to curb the rapid decline of the water level in the middle and lower reaches of the Yangtze River and ensure water intake from irrigation areas and cities along the line, the Ministry of Water Resources has decided to implement the special action of 'Joint Dispatching of Reservoir Groups in the Yangtze River Basin to Fight Drought and Ensure Water Supply ', since 12:00 on August 16, the cascade reservoir group in the upper reaches of the Yangtze River with the Three Gorges Reservoir as the core, the Dongting Lake Xiangziyuanli 'Sishui' reservoir group, and the Poyang Lake Ganfuxin Raoxiu 'Wuhe' reservoir group will be dispatched. Increase the outflow flow to replenish water downstream, and plan to replenish 1.48 billion cubic meters of water." said Liu Weiping, Deputy Minister of the Ministry of Water Resources.
To replenish water, you must first have water.
Wu Daoxi, deputy director of the Yangtze River Water Conservancy Commission of the Ministry of Water Resources, introduced that the Yangtze River Commission dispatched the Three Gorges Reservoir to appropriately raise the operating water level to about 150 meters in mid-to-late July, increasing the available water by nearly 2.3 billion cubic meters, effectively ensuring drought resistance in the middle and lower reaches of the Yangtze River and power grids. Water demand for electricity supply during peak summer.
After the launch of the special operation for the joint dispatch of the reservoirs in the Yangtze River Basin to fight drought and ensure water supply, according to preliminary calculations, it is expected that from August 16 to 21, the reservoirs in the upper reaches of the Yangtze River will replenish 830 million cubic meters of water to the lower reaches.
Through water replenishment scheduling, Shashi, Chenglingji, Hankou and Hukou stations in the middle and lower reaches of the Yangtze River can be raised by 0.4 to 0.1 meters compared to the case of no replenishment.
Beginning in late June, the Jiangxi Provincial Department of Water Resources instructed the reservoirs to increase water storage. By mid-July, the total water storage capacity of the province's reservoirs was 7% higher than the same period of the previous year.
"According to the development trend of the drought, the Xiajiang Reservoir and the Liaofang Reservoir entered the non-flood season management nearly two months ahead of schedule on August 9, with an increase of 65 million cubic meters of water storage." Wang Chun, director of the Jiangxi Provincial Department of Water Resources, revealed that at the same time, Increase water sources according to local conditions. Since July, Nanchang, Jiujiang, Shangrao, Jingdezhen and other places have been guided to take advantage of the favorable conditions of high water levels in the outer rivers and outer lakes, diverting and raising water by 150 million cubic meters, and ensuring an irrigation area of 920,000 mu.
In addition, the relevant reservoirs have been fine-tuned to ensure the demand for irrigation water.
Hunan issued a special action plan in May to make comprehensive arrangements for drought prevention and drought relief. Before the flood season, tasks such as irrigation areas, channel reconstruction, and new repairs and maintenance of rural water supply projects were over-completed, with an additional water supply capacity of 186 million cubic meters.
"We optimize dispatching, insist on pre-storage, joint dispatch, and timely replenishment. Before the end of the rainy season, various water conservancy projects will store 38.66 billion cubic meters of water, which is 8% more than the same period of last year; A total of 1.678 billion cubic meters of water has been replenished in many towns and more than 40 large and medium-sized irrigation areas, which has guaranteed the water demand of nearly 20 million people and more than 9 million mu of crops." said Luo Yijun, director of the Hunan Provincial Department of Water Resources.
It is not easy to transfer water to arid areas, and it is even better to make good use of this water in arid areas.
The Ministry of Water Resources instructs and urges local governments to seize the favorable opportunities for upstream water replenishment, accurately connect with each irrigation area, and each urban and rural water supply intake, divert more, provide more, and adjust more, and make good use of every square of water, so as to provide water source guarantee for the autumn grain harvest and urban and rural water supply. .
By implementing these measures, the bottom line of rural drinking water safety has been maintained.
Chen Mingzhong, director of the Rural Water Conservancy and Hydropower Department of the Ministry of Water Resources, introduced that for the 309,000 people who are currently having difficulty drinking water due to drought, the water supply needs of 47,000 people have been better guaranteed by extending the pipe network and opening up new water sources. Provided drinking water, and basically met the drinking water needs of 63,000 people through measures such as time-sharing water supply.
After active response, more than 2,500 large and medium-sized irrigation areas in 6 provinces (cities) have irrigated more than 100 million mu of farmland, basically ensuring the seasonal irrigation water demand of crops, effectively controlling the affected area of crops, and laying a solid water conservancy foundation for the full harvest of autumn crops.
Based on precise measures to resist long-term drought
Strictly prevent drought and flood
If the drought really develops as the current forecast says, how can the water supply security in the dry area be guaranteed?
Gu Binjie, Inspector Commissioner of the Flood and Drought Disaster Prevention Department of the Ministry of Water Resources, said that the Ministry of Water Resources will focus on fighting long-term and severe droughts, and in accordance with the general requirements of "pre-emptive" and "real" support, continue to "ensure the safety of drinking water for people in dry areas." , Guarantee drinking water for large livestock, and ensure the irrigation water for autumn grain crops" as the goal.
It is embodied in optimizing and standardizing the order of water use—correctly handling the relationship between upstream and downstream, left and right banks, current and future water use, domestic and production water, and ensuring the safety of drinking water for the masses, drinking water for large livestock and irrigation water demand for autumn crops.
Precise scheduling of water conservancy projects - Based on the most unfavorable situation of continuous ineffective rainfall in the later period, formulate watershed and regional water engineering scheduling plans, and implement them accurately; carefully do a good job in the connection of reservoir group scheduling and water users, make good use of every square of water, and do everything possible Meet the needs of the masses for drinking water and irrigation water for autumn crops.
Accelerate the construction of emergency water source projects for drought relief—according to the actual conditions of various places, implement projects such as reservoir-reservoir connection, reservoir-plant connection and other projects as soon as possible to improve the utilization rate of local water resources; in areas where conditions permit, speed up the implementation of raw water mutual aid, clean water complementary projects and cross-county districts Water transfer project; in hilly areas, undercurrents should be intercepted and streams should be diverted to fully tap the potential of existing water sources.
Make good use of comprehensive supporting measures for drought resistance, such as water saving, water transfer, water restriction, water supply, and water pulling, to improve drought resistance.
Organize the cadres and technical personnel of the water conservancy system in the dry area to go to the front line, contract the project and the area, and make every effort to provide technical services and coordinate and guide key tasks such as flood control, flood control of small and medium rivers, and mountain torrent disaster prevention.
At present, my country is still in the flood season. While doing a good job in drought resistance, we must always tighten the string of flood control to prevent the sudden turn of drought and flood.
"We will always maintain the mental state and working mechanism in the critical period of flood control, closely monitor rain conditions, water conditions, and typhoons, strengthen forecasting, early warning, rehearsal, and pre-plan measures, strengthen 24-hour on-duty duty and consultation, research and judgment deployment, rolling forecasts, scientific Dispatching water projects to effectively prevent river floods, focusing on key tasks such as the safety of small and medium-sized reservoirs and check dams, and prevention of floods and mountain torrent disasters in small and medium-sized rivers, to ensure the safety of people's lives and property." Gu Binjie said.
(Reporter Chen Chen of this newspaper)