Hebei and Tianjin flood discharge to protect Beijing? Expert: Inaccurate situation | Compensation. 2000 | Tianjin
Affected by Typhoon Dussuri, the recent heavy rainfall in North China has been fierce, widespread, and intense, with some rivers experiencing varying degrees of flooding. The Beijing Tianjin Hebei region has activated flood storage and detention areas to orderly divert and retain river floods. As of now, Hebei Province has successively opened 7 flood storage and detention areas, completing the transfer of 847400 people.
Flood storage and detention areas are an important component of China's river basin flood control and disaster reduction system, playing an irreplaceable role in defending against major floods in previous river basins, and basically ensuring the safety of important cities and flood control areas in the middle and lower reaches of rivers. According to statistics, from 1950 to 2021, 66 out of 98 national flood storage and detention areas were put into use 424 times, with a cumulative flood storage and detention capacity of over 140 billion cubic meters. The flood storage and detention areas that were gradually put into use in Hebei were also used during the major floods in the Haihe River Basin in 1963 and 1996.
Cheng Xiaotao, Deputy Chief Engineer of China Academy of Water Resources and Hydropower, introduced that flood storage and detention areas are an important component of the flood control system. They are low-lying areas and lakes where temporary flood storage is carried out outside river embankments, most of which have been historically submerged by river floods. When floods are too severe, timely diversion and reduction of flood peaks can minimize disaster losses.
News+Cheng Xiaotao: Flood storage and detention areas are an important component of the flood control system. Floods can be temporarily stored in low-lying areas on both sides of rivers, as well as in wetlands and lakes.
Not all sides of the river are highlands, but there are also areas with lower terrain, which used to be prone to flooding as long as the water rose. With population growth and the construction of dams along rivers, the probability of flooding in these lower lying areas is greatly reduced. Slowly, some low-lying areas were cultivated into farmland, inhabited by people, and gradually formed villages.
When a major flood occurs, in order to alleviate the pressure on downstream cities, it is necessary to reduce the peak flow of the river channel. So some flood diversion and storage areas were set up, and when the flood peak passes through the diversion and storage areas, the flood is directed to the areas outside these large embankments by opening the gates or opening the embankments.
In history, these flood diversion processes may have been naturally formed. In the past, during major floods, these areas were also flooded, but now they have become flood storage and detention areas.
However, the existing embankments and pumping stations have effectively reduced the probability of flooding in these areas. Usually, an additional embankment is built for the flood storage and detention area to prevent the water flowing into the area from spreading everywhere after a flood occurs. Floods are stored in the flood storage and detention area, and after the peak of the river flood passes and the water level drops, the water in the flood storage and detention area is discharged back into the river channel.
Cheng Xiaotao from News+: The cross-sectional size and depth of different rivers vary, so the flood discharge capacity of rivers also varies. When the flood volume exceeds the flood discharge capacity of the river, it is possible for the river to flood.
In order to improve the flood discharge capacity of the river, we built embankments along the river, which is equivalent to expanding the cross-section of the flood discharge. But the embankment is very long, and we cannot guarantee that every place can withstand floods. In order to avoid flooding, we have to carry out full line defense and set up flood storage and detention areas, which can clarify the areas for flood diversion and reduce the flood control pressure on key protected areas. The area that is planned to be submerged by floods is called a flood storage and detention area, which is essentially a measure to relieve the flood control pressure on the entire river channel and ensure the focus of flood diversion.
The flood that flows into the flood storage and detention area will return along the original path after the water level of the main river decreases, and this process is called "receding water". Some flood storage and detention areas have a diversion gate located upstream, and also a discharge gate located downstream, which can discharge water. Floods in these areas are temporarily suspended.
News+Cheng Xiaotao: I don't think this is a very accurate expression. The application of flood storage and detention areas is comprehensively considered at the scale of the watershed. Generally speaking, the effectiveness of flood storage and detention areas is for downstream, not upstream. Therefore, the application of flood storage and detention areas is targeted at Tianjin. The decrease in water level in Tianjin does not mean that Beijing will not be flooded.
News+Cheng Xiaotao: The flood storage and detention area is not only an important component of the flood control system, but also a home for the survival of the people in the flood storage and detention area. The people in flood storage and detention areas are also citizens of the People's Republic of China, and they have the right to development. It is not to say that they should be the objects of sacrifice.
So when the Flood Control Law of the People's Republic of China was formulated in 1997, it was clear that if the state used flood storage and detention areas, compensation should be provided. The Provisional Measures for Compensation for the Use of Flood Storage and Detention Zones, issued in 2000, also provide detailed explanations on the compensation standards.
