What are the reasons for the flood of ice?
The natural conditions of ice flood depend on the geographical location and channel shape of the river. In the alpine region, the river flows from low latitude to high latitude, and the shape of the river channel is wide and narrow, so it is more likely that serious ice flood will occur where the river channel bends into a ring.
The upper reaches of the Yellow River in China are Ning (Ningxia), Meng (Inner Mongolia) and its lower reaches, and the tributaries of Heilongjiang are Songhua River, Wusuli River and Irtysh River. Russian neva river, North Dvina River, Yenisei River and Lena River; Hamburg section of the lower Elbe River in Europe, Federal Republic of Germany; Montreal section of St. Lawrence River in Canada, etc. -These are the major rivers with severe ice storms and floods in the world.
In winter, the downstream temperature drops early and freezes first. After the downstream icing, the ice layer has the function of blocking water, and the cross section of water decreases, which affects the discharge capacity. In this way, part of the water is trapped in the upstream channel, and the water level rises accordingly. In spring, the temperature rises early in the upper reaches of low latitudes, and the river starts from top to bottom. When the ice water from the upstream spreads downstream, it often gets stuck where it meets a narrow reach or bend, while the hard and thick ice layer that is still "sleeping" in the downstream makes the ice accumulate horizontally along the river, just like a river dam, which blocks a lot of ice water and makes the water level rise rapidly. Ice relies on water potential, and water helps ice. Ice outposts, such as giant bulldozers, are unstoppable, which will seriously damage downstream dikes and nearby buildings and cultivated land, especially piers. The severity of ice flood depends on the influence of river ice on water level. Usually, the water level will rise sharply only after serious ice or ice dam appears in the river, causing serious ice flood.
What is Lingxun Phase III?
According to the formation and development of ice flood, it can be divided into "ice flood season", "freezing period" and "river opening period"
Take the Yellow River as an example. During the ice jam, the temperature in the lower reaches of the Yellow River dropped below zero degrees Celsius in winter, and the water temperature reached zero degrees Celsius. The river began to freeze and ice flowers were produced in the water. Ice flowers gradually condense into ice hockey or ice cubes with the water flow, commonly known as dripping water. Generally speaking, the flow period is mostly in 65438+February.
Sometimes you will see "flat printing" and "vertical printing". What's the difference between them?
Flat seal means that when the river freezes, the ice in a certain reach freezes to form a flat seal of the river. Plane sealing mainly occurs between inserted river sections. Due to the influence of low temperature, the ice on both sides of the river gradually widens and thickens, and freezes with the ice on the river surface to form a flat frozen ice sheet.
This seal is also called "plug-in seal". During the freezing period of river flow, after a large number of ice jams in the narrow and curved reach, ice cubes are inserted from bottom to top, and some ice cubes are inserted up and down under the action of hydrodynamic force, forming a freezing situation in which ice cubes overlap and are blocked vertically.
What is "Wu Kaihe"? What is "Kevin Ho"?
During the ice flood season, when the upstream of the river is opened to melt ice, the downstream is still frozen, and a large amount of ice water from the upstream rushes to the downstream, forming a large ice flood peak, which is easy to block ice and build dams in the curved and narrow reach, blocking the high water level and causing ice flood disasters. During the thawing period of the river, if the temperature rises rapidly, or the upstream water suddenly increases, the river ice can suddenly break and melt quickly, becoming the "Wukai River". In some years, the temperature difference between the upstream and downstream is not big, and the river is thawed in sections or in situ, so as not to form a big ice flood, and the river is relatively smooth, becoming the "Kevin River".
What are the characteristics of the Yellow River ice flood? Why is there a saying in history that "the ice burst its banks and the river official is innocent"?
There are two characteristics of the Yellow River ice flood: First, although the flow in Ling Feng is small, the water level is high. Because there is ice in the river, the flow resistance increases and the flow velocity decreases, especially when ice jam and dam construction are carried out, the water level in the river is high, and the water level with the same flow rate is much higher than that in the ice-free period, even exceeding the highest flood level in the flood season. Second, the water storage capacity of the river is gradually released, and the flow of Ling Feng is increasing along the way. For example, the peak discharge of Shizuishan ice flood in Ningmeng reach of the Yellow River is generally close to 1 0,000 cubic meters per second, while that of Guatou can reach 2,000 cubic meters per second, and the maximum reaches 3,500 cubic meters per second at 1 0,968.
The sudden ice flood of the Yellow River makes it difficult to predict the location of ice dams, which may lead to many accidents. The water level rises rapidly, and once the river is opened, it will form a water-blocking ice dam, which is very destructive. Because it is difficult to borrow soil from frozen soil and break the ice dam, there are few ways. Therefore, in history, the ice flood is regarded as an irresistible "natural disaster" by human beings, so there is a saying that "the ice flood burst its banks and the river official was innocent".
What anti-icing measures are there?
Because there are different kinds of ice disasters, different preventive measures need to be taken:
Ice will freeze rivers, lakes and ports and affect shipping and traffic. Icebreakers can be used to break ice, or air filters can be used near the port shore and ship locks.
Ice will freeze the diversion canal of hydropower station or block the trash rack, which will affect the power generation output. Measures can be taken to raise the water level of the canal, promote the formation of ice sheets and prevent ice.
Ice will freeze the gates of various water discharge structures and affect the opening and closing operation. Generally, heating or other anti-freezing measures are adopted.
When ice impacts buildings, such as piers, piers and groins for river regulation, measures such as local reinforcement or breaking large pieces of flowing ice are often adopted.
When the ice sheet expands, it will produce great expansion force and increase the load of the building, which should be taken into account in the design of the building. Measures can also be taken, such as installing a surface-bottom water flow exchanger on the water surface of the building to prevent icing, or placing a circular buoy to reduce ice pressure transmission.