The Three Gorges Reservoir Area has vacated 30 meters of storage capacity, and the water level has dropped to 145 meters, can it ensure the safety of the middle and lower reaches of the Yangtze River?
Last year, the time of the Yangtze River Basin flooding was May 22, and dozens of rivers had super-warning floods, but the specific time when the provinces in the basin entered the flood season were not necessarily the same, some earlier, some later.
On April 1, Jiangxi Province entered the flood season in an all-round way, and the Provincial Meteorological Bureau predicted that the flood prevention and drought control situation was complicated; on April 15, Zhejiang Province officially entered the flood season, and the province's water conservancy system directly entered a 24-hour duty state. Many people may think that this is not too early, and the flood season of the Yangtze River is not concentrated in May to October every year?
Moreover, the specific flood time also has a basis for judging, when any flood representative station exceeds the alert water level, or the rainfall for 3 consecutive days exceeds 50 mm, and the coverage area reaches 150,000 square kilometers, then it can be confirmed that the flood season has entered!
Many people may have seen that in order to ensure the safety of the middle and lower reaches of the Yangtze River, the Three Gorges Reservoir on the main stream of the Yangtze River has dropped the water level from 175 meters to 145 meters, and the 30 meters of storage capacity vacated are actually specially reserved for flood prevention. People who live near the Three Gorges Dam can see that the current pre-dam water level in the upper reaches of the Three Gorges Dam has dropped significantly compared with the previous period, which is the so-called "Tengku model" of the Three Gorges Reservoir.
Like many large-scale water conservancy projects, it is inevitable that there will be different voices at the beginning of construction, after all, the input costs of these projects are calculated according to hundreds of billions. As we all know, the Three Gorges Dam has both flood control and drought control, power generation and navigation functions, so the Three Gorges Reservoir has never vacated the storage capacity after its completion, but this has not affected its flood control capacity, taking 2021 as an example: the Three Gorges Dam has stored 7 floods, and the flood barrier is 28.6 billion cubic meters, which has greatly reduced the pressure on the safety of the middle and lower reaches of the Yangtze River!
In fact, the important purpose of the construction of the Three Gorges Project is to prevent floods, which can also be seen from its storage capacity design, which has a total capacity of 39.3 billion cubic meters, of which the flood control reservoir capacity is as high as 22.15 billion cubic meters, which is about equal to the flood storage capacity of the four Jingjiang River flood diversion areas.
In addition, the dispatching party of the Three Gorges Reservoir will actually be determined according to the upstream water flow, and the Three Gorges Group will be responsible for the dispatching work when it does not exceed 30,000 cubic meters per second, and the Yangtze River Water Conservancy Commission will be responsible for the dispatch when it exceeds. Moreover, whether it is water storage or water replenishment, the dispatch of the Three Gorges Reservoir must ensure flood prevention and safety.
In 2022, the safety of reservoirs is facing a major test, why is the Yangtze River Basin bearing the brunt of it?
Judging from the situation predicted by the Ministry of Water Resources, the overall deviation of the meteorological and hydrological year of the 2022 flood season on the mainland, the safety of the reservoir will face a major test, and the southern and northern parts of the continent have a greater possibility of flooding, of which the flood in the north may be greater than that in the south, and the central part has a greater possibility of drought.
To deal with this problem, the first thing to do well is to implement the operation and management responsibility of the reservoir dam, what preparations are made before the flood, how to deal with it when the flood season comes, and all preventive measures must be refined.
In addition, for the sick reservoir, it is necessary to speed up the reinforcement of the risk, after entering the main flood season, in principle, all the sick reservoirs are empty reservoir operation, in the process of reservoir operation, timely investigation and rectification of hidden dangers in the reservoir, to come up with a specific and feasible flood control scheduling plan to cope with the flood season.
Not every reservoir is as famous as the Three Gorges Dam and the Gezhou Dam, so many people may not know that there are actually more than 50,000 reservoirs in the entire Yangtze River Basin. Of course, in addition to the lack of scale and function, this may also be related to the relatively old age of construction.
Although there are more than 50,000 reservoirs in the Yangtze River Basin, most of them were built in the 1960s and 1970s, which led to the current situation that the reservoirs with disease risk are large and the safety of floods is poor. In addition, global warming does lead to frequent extreme weather events, which makes regional droughts and floods more normalized, and the rapid turn of drought and flooding makes the pressure on reservoir safety to flood even more.
Nowadays, extreme flood and drought disasters occur frequently, why is it difficult to accurately predict? How to scientifically deal with flood and drought disasters?
First of all, it should be clear that there is still a difference between climate prediction and the weather forecast that everyone looks at on weekdays, and the weather forecast mainly affects the time of recent days, concentrated within 2 weeks; and the climate forecast provides a basis for how to arrange a longer period of time, and the time period must be more than two weeks. In fact, 2022 is also the second year that the National Climate Center has released climate forecasts to the public, and there are many countries in the world that have carried out climate forecasts, but not all of them have released the results of the forecasts to the public.
In fact, it is not strange that it is difficult to accurately predict the climate, after all, the geographical location of the continent is also relatively special, there is the Qinghai-Tibet Plateau in the west, everywhere in the northwest pacific, the southeast edge of eurasia, they are the third pole of the earth, the largest ocean, the largest land, so there are many factors that will have an impact on the continental climate, which will make researchers encounter a lot of difficulties in the analysis, fortunately, no matter what kind of climate prediction method, they are developing with scientific progress. Awareness of climate phenomena is increasing.
As we all know, Zhengzhou experienced a huge flood last year, which was also an extreme flood, which reminds us that even if we work in the office on weekdays, we do not need to farm and cultivate land, but we still need to pay attention to meteorological early warning information, prepare for risk avoidance and self-protection in advance, and improve the infrastructure and improve the response ability of sudden natural disasters. For example, when the rainfall is too large in a short period of time, it is necessary to use the drainage and flood control engineering system, and at the same time, it is also necessary to improve the emergency organization and rescue capabilities.