Lingxun, commonly known as Bingpai.

It is a hydrological phenomenon in which river water levels rise significantly due to the resistance of ice to water flow. Ice flakes can sometimes gather into ice jams or ice dams, causing water levels to rise significantly and eventually overflow or break banks, which is called a flash flood. Freezing floods may occur during the river closure period in winter and the river opening period in spring. In layman's terms, there is ice on the water surface, which breaks into blocks, and there is water flow under the ice, which drives the ice blocks to move downstream. When the river bank is narrow, the ice layer continues to accumulate, causing excessive pressure on the bank, which is called freezing floods.

① Flood hazards caused by ice jams. It usually occurs during the freezing period, and often occurs at the backwater end of the reservoir where the steep slope changes. It lasts for a long time and gradually raises the water level, causing greater harm to engineering facilities and humans. ② Flood hazards caused by ice dams. Usually occurs during the thawing period. It often occurs in river sections with a large latitude difference between south and north. After the ice dam is formed, the water level upstream of the ice dam rises sharply, the embankment breaks, and flooding occurs. ③Hazards caused by ice pressure. Ice pressure is the force that ice acts directly on a building, including the dynamic pressure generated by the impact of drifting ice, the static pressure transmitted to the building due to the shear force of wind and water due to the large area of ????ice, and the entire ice The static pressure generated by the expansion of the capping layer. In February 1929, an ice dam blocked a river in Lijin County, Shandong Province, causing a breach and flooding more than 60 villages in Lijin and Zhanhua counties.

Ling floods in the Yellow River

Ling floods are a common natural phenomenon in the Yellow River, which is a temporary rise in water caused by ice blockage. Because the Yellow River is located at a high latitude, the lower reaches of the river are usually frozen and closed in winter. When the ice thaws and the river opens in early spring, the ice and water rush down, the ice blocks the river, and the water level rises, forming a cold flood. This period is the cold flood season of the Yellow River. Because the latitude of the upper and lower reaches of the Yellow River differs by more than 3 degrees, the average winter temperature differs by 3 to 4 degrees Celsius. The upper section of the river freezes late and opens early, resulting in thinner ice; the lower section of the river freezes early and opens late, resulting in thicker ice. Generally, between January and February, when the temperature rises, the frozen upper section of the low-latitude river section first thaws and opens up. During the freeze period, the accumulated water in the river channel is released rapidly, forming a freezing flood. The peak flow increases along the way and the water level rises; but the lower section of the high-latitude river section Because the temperature is still low in this section, the ice is frozen. Under the action of water flow, the ice drum opens, forming the "Wukai River". During the "Wukai River", the thaw comes quickly, especially when the temperature rises sharply or the water level rises sharply, and large ice flakes surge down, which easily causes ice flakes. Sometimes a large number of ice flakes block narrow, curved, and shallow shoals, forming ice jams and ice jams. The dam causes the water level to rise sharply. Due to the plugging of ice and drift ice, the flow area is reduced and an ice dam can be formed. As the water level increases, water drums and ice will crack and the ice will overflow the embankment, causing disasters. The level of damage often exceeds that of floods. In some years, the temperature changes in the upper and lower river sections are not much different, and the frozen river is thawed in sections or on the spot to open the river, which avoids large-scale cold weather floods and the river opening is relatively smooth and smooth. This situation is generally called the "Wenkai River".

Freezing floods occur due to the existence of ice. Ice is the dominant factor in producing freezing floods, so ice-breaking methods are used to prevent and control them. The measures taken include breaking ice, spreading soil, icebreakers, explosive blasting, artillery bombing, and aircraft bombing the ice. It also summarized the experience of ice breaking: first pay attention to grasp the ice condition forecast, choose the ice breaking time, and the ice breaking is most effective when the river is about to open. If it breaks early, it will freeze again when the temperature drops; if it breaks late, the opportunity to break the ice will be lost. When the river is long and the amount of ice is large, it is also necessary to choose important river sections where ice may form and house dams submerged by ice, such as shoals, sharp bends, and narrow embankment distances, etc. to break ice.