Poyang Lake and Dongting Lake 'shrink' one after another: the lake has become a prairie, what signal is released here
In 2022, the earth will be affected by extreme climate change, with the strongest summer heat, however, the drought caused by the heat is also very serious. In China, for example, the drought in the Yangtze River region was so severe that many rivers were cut off and a large number of "cracks" appeared on their banks.
In winter and spring, however, news of Poyang Lake 's "Great Lakes turning into grasslands" is not uncommon, with the lakebed turning into meadows and coastal roads crammed with tourists' private parking spaces. Why does the water level of Poyang Lake fluctuate differently in different periods? In this episode, Ma Hanfang, a senior geography teacher at Hangzhou Qian Xuesen Middle School, was invited to explain the mystery of the Poyang Lake water level.
The water bodies of Poyang Lake and Dongting Lake are shrinking and water resources are decreasing. Will there be such "rare water" next year?
A rare situation
However, behind this kind of joke, there is stark data displayed in front of people. According to reports, 51 rivers in Chongqing, including Sichuan, Chongqing, Hunan, Hubei, Jiangxi and Anhui , are in danger of being cut off, and 9.67 million mu of farmland has not been irrigated by rain for a long time.
The Jialing River shoal is exposed to the ground, and the "Buddha's feet" of the Leshan Giant Buddha are completely exposed , which also shows how serious the dry weather is today. According to Pengpai News, Dongting Lake and Poyang Lake entered dry water ahead of schedule, and now 830,000 people are affected. These two large lakes in the middle and lower reaches of the lake have a maximum water storage capacity of more than 40 billion cubic meters , while the water storage capacity of Poyang Lake exceeds 50 billion cubic meters . Now, these two large lakes are covered with water grass covered. This also makes people wonder, why is the drought so severe during the flood season? In fact, there are several main reasons.
2. Reason analysis
First of all, it can be seen in the most direct and simple way that the amount of water has been gradually decreasing . To be precise, the amount of precipitation is much lower than the historical period.
Second, the water level continues to drop. The water flow of major lakes and waters has decreased significantly, and the water levels of the Three Gorges of the Yangtze River, the Danjiang Estuary of the Han River and other reservoirs are also about half lower than in previous years. In particular, during the flood season, Dongting Lake and Poyang Lake may accumulate a lot of water, and even replenish the water in the middle and lower reaches of the Yangtze River. If the two lakes are short of water, the water from the Yangtze River will flow into the lakes to alleviate the drought of the two lakes.
Currently, however, the entire Yangtze River Basin is experiencing drought, with two lakes entering the dry season 100 days ahead of schedule . Therefore, it has also attracted public attention. On top of that, the impact of persistent high temperatures has led to a return to drought in many places during the flood season, as is the case in Dongting Lake. Since August 4, the water level at Chenglingji Station of Dongting Lake has been below the dry level of 24.5 meters . Compared with the dry water level of 24.5 meters around October 26 every year, the dry season has entered the dry season more than 80 days earlier this year. However, the severe drought continues, with forecasts showing it will continue until the end of August.
There is no doubt that the severe water shortage in these two lakes has severely affected industrial and agricultural water use in Hunan and Jiangxi provinces. Water resources are so scarce that there is an urgent need to build comprehensive water conservancy control projects for these two lakes , which are the Dongting Lake Dam and Poyang Lake Dam that many people yearn for.
There is no clear plan for the construction of the Dongting Lake Dam . Some people think that Yueyang is the core location of Dongting Lake, located at the exit of Dongting Lake, that is, the 15.8-kilometer -long waterway from Junshan to Chenglingji. There are four dam sites within 15.8 kilometers . Two of them are ideal, namely the upper dam site is about 3.5km away from Junshan to Nanjin Port , and the lower dam site is about 3.2km away from the Dongting Lake No. 1 Bridge on the Hang-Rui Expressway to the proposed Dongting Lake No. 2 Bridge . Most people tend to choose the latter, because the project scale may be small, and the Qili Mountain at the lower dam site is the most ideal dam site.
The design principles of the Poyang Lake water conservancy project are: no power generation to block water, no gates, no dams, no flood control, no scheduling and construction of pipes , and the needs of water ecological protection and water resource utilization in the Poyang Lake area and the middle and lower reaches of the Yangtze River are comprehensively considered . However, the lack of water in Poyang Lake and Dongting Lake this year actually forced the designers to rethink the design concept of the project. If the dam body is too low or there is no dam body, and the water resources of Poyang Lake are not preserved during the flood season and flood season, I am afraid that the water demand of the Poyang Lake area will not be guaranteed for a long time.
If there is no water after the completion of the flood season like this year, the construction of the water conservancy project will also lose its function, and these phenomena and problems also apply to the Dongting Lake water conservancy project. Therefore, the "thin" Dongting Lake and Poyang Lake in the flood season actually forced the dams of these two lakes to be built as soon as possible , and it is believed that with the urgency of water resources utilization , the construction date will be faster.