Control of sandstorm weather in Beijing

For more than 50 years, Beijing and Tianjin have been using afforestation to control sandstorms. Although some achievements have been made, it has not effectively weakened the "sandstorm". Because the so-called sandstorm in Beijing and Tianjin is not a sandstorm, but a sandstorm. Dust storms rise high and move far, drifting from 2000 meters above sea level to more than 3000 meters. Afforestation can't restrain or mitigate its impact. Therefore, for the control of sandstorms in Beijing, we should start with the restoration of the ecological environment in the arid salt lake area, and cover the dust source with grass with greater density (coverage) instead of "blocking" with wood.

Controlling sandstorms in Beijing begins with repairing dry salt lakes.

"Choosing the local pioneer plants with the strongest vitality and living in extreme environment, covering the dust source area in carpet and repairing the damaged ecological environment is the best scheme to control dust storms in Beijing and Tianjin." Lin Jingxing pointed out that Suaeda salsa is the most suitable native vegetation for planting in arid salt lake areas at present.

Increase investment in environmental protection.

The key to eradicate sandstorms is to eradicate sand sources. And the way we can do it is to adopt interplanting agriculture. Vigorously develop the garden economy and do a good job in soil and water conservation in the northern region. Improve the survival rate of artificial afforestation, and increase investment in garden funds and science and technology.

Yanshan Mountain and Taihang Mountain control the planting of corn, millet and sorghum, and return farmland to forest and grassland (develop economic forest and economic vegetation) with a slope of more than 25 degrees. Rationally plan the layout of cash crops and food crops, and improve the effective coverage of many bare land in planting. Shorten the time of bare land as much as possible, especially the high incidence period of sandstorms from March to May. Increase labor input and improve the water quality of plantation cultivation. Forest vegetation has many functions. Tall trees and low shrubs have good windproof effect. The so-called windproof function is not to prevent the occurrence of strong winds, but to reduce the wind speed. In the 1970s and 1980s, Beijing put forward the slogan of checking the air duct to block the air outlet, which was unscientific, because both the air duct and the air outlet could not be blocked, so we had to find ways to reduce the wind speed. When the strong wind passes through the forest, the wind speed will be reduced because it is blocked, and the sand carried by the strong wind will land in front of and in the forest, thus slowing down the sandstorm activity. Above the forest, the wind speed will also decrease. When the wind speed drops below that of sand, sandstorm activities will naturally weaken or stop.

Plant trees and grass to improve vegetation coverage. In North China, the grassland area of North China Plain is small. Every year from March to May, all kinds of grass seeds grow one after another, which has a strong protective effect on this area and has realized greening protection for a long time. For the severe sandstorm in North China, the dust source is insufficient. Dry rivers, abandoned farmland (covered by weeds) and rural dirt roads all have some dust sources, but their total proportion is too small to become sand sources of sandstorms. The above-mentioned dust and floating dust combine under the action of strong wind and float with the wind, causing air pollution in Beijing and contributing to dust storms. Sandstorm activities and sandstorms are the result of strong winds acting on the sand surface. Therefore, the basic principle of preventing and controlling sandstorms is to fix quicksand and reduce wind speed. The wind speed at which quicksand is blown off the surface is called sand-raising wind speed. The wind speed of blowing sand is related to the size of sand and the degree of dryness and wetness. As far as Beijing is concerned, when the wind speed reaches 4-5 m/s, there will be sandstorms. If there is forest vegetation on the surface, the roots of plants can fix quicksand and reduce sandstorm activities. There are three main types: one is to plant trees and grass, which is called biological sand control. The second is to set up sand barriers, which are called engineering sand control. The third is spraying coagulant, which is called chemical sand control. Among them, biological sand control is the best sand control method, which is widely used in the world. Engineering sand control is an auxiliary means, and chemical sand control is rarely used in China. Pay attention to the combination of biological measures and engineering measures to control sandstorms.