The hazards of sandstorms are mainly two, one is wind and the other is sand. Let's say the wind first. Strong winds damage buildings, blow down or uproot tree or poles, tear up farmers' plastic greenhouse and farmland mulch. In addition, because May of the northwest region is a good time for growth cotyledon or the real leaf period and the flowering period of the fruit trees, vegetables, sugar beet, cotton and other economic crops seedlings, so it can’t withstand wind and sand mostly. If the level of influencing is low, then leaves are covered with dust, which weakens photosynthesis and affects respiration, reducing crop yield. If it is high, it will be dead, not to mention blossom and fruit. For example, on May 5, 1993, the wind had caused 85,000 fruit trees in the northwest to be knocked down, and 10.94 million shelterbelts and timber trees were broken or uprooted.
In addition, the winds blowed down the electric pole causing the water outage, affecting industrial and agricultural production. On May 5, 1993, there was a power outage caused by high winds, and only one company suffered an economic loss of more than 80 million yuan. When wind blows over loose soil in dry areas, it scrapes a layer of soil on the surface, this is called wind erosion. For example, on May 5, 1993, the land suffered from wind erosion of average depth of 10 cm with maximum depth of 50 cm, which means that the fertile soil on the surface with an average of 60 to 70 steres per acre was blown away by the wind. In fact, the wind not only blowed away the fine clay and organic matter in the soil, but also deposited the sand in the soil, which greatly reduced the soil fertility. In addition, the sand grains also grind the surface of buildings and crops, which is called abrasion that is also a kind of disaster. The harm of sand is mainly sand burial. As we mentioned above, under the terrain like the throat pipe, the wind and uplift, sand hazards is mainly erosion because the wind speed is high. However, in the leeward terrain with slow wind speed, the hazard is mainly sand burial. For example, in the palce that the sand was buried in the gale on May 5, 1993, the thickness of the sand was 20 centimeters on average and the thickest place was 1.2 meters. And more importan are loss of lives. For example, on May 5, 1993, 85 people died in the gale, 264 injured and 31 were missing.
In addition, 120000 livestock died or were lost, crops of 5.6 million mus were affected, the length in arid region of the sand buried lifeline channel is more than 2000 km, Lanxin railway was suspended for 31 hours and the total economic loss reached more than 500 million yuan.
Human and livestock deaths, collapses of building, crop failure show the hazards to people and livestock of sandstorms are no less than typhoons and tornadoes. In recent years, there have been more than 20 sandstorm attacks in northwest China, resulting in more than 1.2 billion economic losses and more than 200 dead and missing persons.
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