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Sandstorm is the general term for both sandstorm and dust storm. It refers to a weather phenomenon in which strong winds roll a large amount of sand and dust from the ground into the air, making the air particularly turbid and with horizontal visibility less than 1 km. Sandstorm refers to strong winds. A sandstorm is formed when a large amount of sand is blown into the near-surface layer; a dust storm is a storm formed when strong winds carry a large amount of dust and other fine-grained materials into high altitudes. Wind speed and visibility are generally used to classify sandstorm intensity levels. Currently, the intensity of sandstorms is divided into four levels: Level 4 ≤ wind speed ≤ level 6, 500 meters ≤ visibility ≤ 1000 meters, which is called a weak sandstorm; Level 6 ≤ wind speed ≤ level 8, 200 meters ≤ visibility ≤ 500 meters, which is called a weak sandstorm. A moderate-intensity sandstorm; wind speed ≥ level 9, 50 meters ≤ visibility ≤ 200 meters, is called a strong sandstorm; when it reaches its maximum intensity (instantaneous maximum wind speed ≥ 25 meters/second, visibility ≤ 50 meters, or even reduced to 0 meters), It is called an extremely severe sandstorm (or black storm, commonly known as "black wind"). ?

The hazards of sandstorms can be roughly summarized into four types: sand burial, wind erosion, strong wind attacks and atmospheric environment pollution.

Due to wind and sand, the amount of dust emitted into the air from the entire earth every year amounts to 2 to 200 tons per square kilometer. According to observations, dust in Central Asia can be carried by westerly airflow to the Hawaiian Islands 10,000 kilometers away. These dusts contain many toxic minerals, which are harmful to the human body, livestock, crops, forests, etc., and can cause eye diseases, respiratory infections and other diseases in people.

On the afternoon of May 5, 1993, a strong sandstorm occurred in the northwest region. First, a wall of wind and sand appeared in the northwest of Jinchang. Ten minutes later, strong winds blew, sand and dust rolled, and the sky became dark. , I couldn't see my fingers out of my hand, and there were dull thunderous sounds from time to time, and an extremely terrifying scene suddenly appeared between the heaven and the earth. This state lasted for nearly 3 hours in Jinchang City, and swept eastward to Wuwei, Baiyin in Gansu Province, Alxa League in Inner Mongolia, and central Yinchuan in Ningxia, ravaging a 500-kilometer radius and lasting for 5 hours, causing casualties and injuries. , hundreds of people were missing, direct economic losses reached 540 million yuan, and it also caused many environmental problems.

1. Macroscopic measures

① Carry out extensive and in-depth publicity and education on environmental awareness to improve the ideological and cognitive level of the entire nation. Care about and protect the environment, consciously participate in transforming and building the environment, and form a trend throughout society.

② Improve laws and regulations, strengthen law enforcement supervision, protect the environment in accordance with the law, and promote desertification prevention and control.

③ Strictly implement the family planning policy, control excessive population growth, and continuously improve the quality of the population.

④Develop various scientific and educational undertakings in desertified areas. Cultivate the scientific and technological strength at the grassroots level, improve the rural science and technology market as soon as possible, provide scientific and technological services, and improve the cultural and technical quality of the people in desertification areas.

⑤ Establish an effective investment mechanism to prevent desertification and a management mechanism that is in line with the current national conditions.

⑥Establish an advanced desertification dynamic monitoring and forecasting system, make good decisions, and improve information management and services.

⑦ Carry out a lasting green revolution in desertified areas to accelerate the reversal of the desertification process and gradually improve the basic functions of the agricultural ecosystem.

⑧ Strengthen international exchanges and cooperation in combating desertification and strive for funds and foreign aid.

⑨ Accelerate the adjustment of industrial structure, rationally allocate the proportion of agriculture, forestry, animal husbandry, and sideline industries in accordance with market requirements, actively develop breeding and processing industries, divert rural surplus labor, and reduce population pressure on land.

⑩ Optimize the energy structure of agricultural and pastoral areas, and vigorously advocate and encourage the people to use unconventional energy, such as wind energy and light energy, to reduce the damage to forests, grassland and other resources.

2. Technical measures

(1) Biological measures

①Seal sand to cultivate forests and grass, and restore natural vegetation

Implement certain measures Protective measures (set up fences), establish necessary protection organizations (forest protection stations), strictly prohibit damage by humans and animals, give plants time to thrive, and gradually restore natural vegetation. At the same time, artificial replanting and management can be carried out during enclosure to accelerate ecological reversal.

②Aerial seeding, afforestation, grass and sand fixation

Aerial seeding has the characteristics of fast speed, less labor, low cost and good effect, especially for vast areas, sparsely populated areas, inconvenient transportation, remote desert sands , restoring vegetation in barren mountain areas is of greater significance. The key technical issues to be solved for aerial seeding include: predicting climate, selecting site conditions, determining suitable sowing areas, determining appropriate sowing volume, seed treatment technology, prevention and control of bird and animal diseases and insect pests, closure and protection, etc.

③ Fix the quicksand through plant sowing, cuttings, seedlings and grass planting

Live broadcast afforestation and sand fixation: Sow seeds on the grassland quicksand to ensure that the seedlings reach a certain density (15-20 plants/m2) , with a certain height (15-20cm) and a certain area (>1000m2), wind erosion can be transformed into plant groups buried in the sand, and the dunes can be fixed. The plant species that have been successfully broadcasted are mainly two sand-growing pioneer plants, namely flower stick and poplar. It can be sown by broadcast, drill or hole sowing.

Afforestation and sand fixation by planting seedlings: In the flowing sandy land of arid grasslands, appropriate deep planting and reasonably dense planting methods are used to fix the sandy land. For example, Changmaotan Forest Farm in Dingbian uses ditch planting method to densely plant Artemisia oil on the sand dunes in autumn to form a sand barrier.

Afforestation and sand fixation through cuttings: Sand willow cuttings are used to directly fix sand dunes in the quicksand areas of Shaanxi and Ningxia. Yulin people use the cluster planting method to form a sparse and dense pattern, which not only resists wind erosion but also solves the problem of water shortage. The spacing between clusters is 0.5m×1.5m, and there are 4 to 5 cuttings in each cluster.

④Establish a protective forest system in sandstorm areas

The oasis protection system in arid areas: the first is the enclosed shrub and grass sand-fixing belt outside the oasis, the second is the backbone sand-proof forest belt, and the third is the farmland inside the oasis Forest nets and other related forest species. The real situation is much more complicated than the typical introduction, and it must be applied flexibly according to the actual situation.

Sandy farmland shelterbelt: Semi-humid areas have more rainfall and better conditions. They can be dominated by trees, and the main belt distance is about 350m. The conditions in the eastern part of the semi-arid area are slightly better, while the western part is on the edge of dry farming and has very poor conditions, with desertification being the most serious. Sandy grasslands generally do not suffer from wind erosion, but due to large-scale reclamation and dry farming, wind erosion develops and requires protection from forest belts. Trees can still grow in the east, reaching a height of 10m, and the main belt distance is 200-300m; in the vast dry farming areas in the west, except for areas with better conditions where arbor forests can be established, drought-tolerant shrubs are the mainstay in other areas, and the main belt distance is only about 50m. Arid areas have many hazards from wind and sand, so small grids and narrow forest belts are used. The main belt distance in northern Xinjiang is 170~250m, and the secondary belt distance is 1000m; the windy sand in southern Xinjiang is large, and a 250m×500m grid is used; the windy and sand front uses a (120m~150m)×500m grid. There are many tree species to choose from, mainly trees. .

⑤Pasture protection forest in sandy areas

Pastoral protection forest construction technology: When selecting tree species, attention should be paid to their feeding value. Trees are the main species in the east and irrigation is the main species in the west. The main belt distance depends on the degree of wind and sand damage. If it is not serious, the maximum protection distance can be 25 hours. If it is serious, the main belt distance can be 15 hours. For sick young female animals, the grazing area can be 10 hours. The distance between the auxiliary belts depends on the actual situation, generally 400 to 800m, and there is no auxiliary belt for mowing the grassland. The distance between the main shrub belt and the forest belt is about 50m, the main belt is 10-20m, and the secondary belt is 7-10m. Considering that the grassland is vast and has few forests, and is dry and windy, in order to form a forest environment, the forest belt can be wider, with 6 to 8 rows of forest belt in the east, 4 to 6 rows of trees, and one row on each side. It should be a permeable structure or a ventilated structure without shrubs. The biological fence should be in a tight structure. The density of afforestation depends on the water conditions. If the conditions are good, it can be denser, otherwise it can be thinner.

(2) Engineering measures

Sand barriers: Use branches, firewood, straw, gravel, clay, laths, plastic boards and similar materials to set up various forms of barriers on the sand surface. Obstacles are used to control the direction, speed, and structure of wind and sand flow to achieve the purpose of fixing sand, blocking sand, blocking sand, preventing wind, and transforming terrain. Sand barriers play an important role and cannot be replaced by biological measures.

According to different sand control principles and installation methods, sand barriers can be divided into two types: flat sand barriers and vertical sand barriers. The tiled sand barrier is a sand-fixing sand barrier that uses firewood straw, pebbles, clay, etc. to spread the sand surface comprehensively or in strips to isolate the contact between the wind and the sand surface, resulting in the effect that although the wind passes by, the sand cannot be lifted. It fixes quicksand in place and protects plant growth, but it has little effect on blocking sand particles in the wind-sand flow. This measure has a greater effect in the eastern region and affects water and ground moisture in the western region, but it is beneficial to the improvement of sandy soil. Vertical sand barriers are sand-accumulating sand barriers. When the wind sand flow encounters any vertical sand barrier, the wind speed will decrease, and part of the sand carried by the wind will be deposited in front of and behind the sand barrier, thereby reducing the amount of sand transported. Vertical sand barriers configured in multiple rows can play a role in fixing the sand surface between barriers and intercepting sand particles in operation. Since most of the moving sand grains are within 30cm of the surface, and most of them are within 10cm of height, there is no need to set up excessively high sand barriers to fix sand and control sand flow to prevent sand damage.

Chemical sand fixation measures: Spray diluted chemical substances with a certain glue structure on the surface of quicksand. The water will penetrate quickly, and the chemicals will stay in the gaps between the sand layers of a certain thickness (1~5mm). Form a hard protective shell to enhance the wind erosion resistance of the sand surface and achieve the purpose of sand fixation. Dozens of chemical sand fixation materials have been developed, but due to high cost, they have not been widely promoted.

Wind sand control: It is an output-based sand control measure that reduces roughness, strengthens the wind force, and makes the sand flow unsaturated, causing the effects of sand pulling and surface wind erosion.

Agricultural measures: First, develop water conservancy, expand irrigation area, increase fertilizer application, and improve soil; second, prevent wind erosion and drought farming operations, such as strip tillage, planting of high-stem crops, etc.