Natural factors influencing blown sand hazards in Beijing

In this article, natural factors in the farming-pastoral ecotone that might have influenced the blown sand hazards in Beijing in 2000 are analyzed. In the farming-pastoral ecotone, blown sand activities took place primarily in springtime, during which 39.8 percent of the annual frequency of erosive winds above threshold occurred. The prevailing directions of the erosive winds were NNW, NW, NWW, and N, with frequencies of 47, 20, 13, and 9 percent respectively. Sand entrainment and dust emission are influenced by erosive wind frequency, soil moisture, and land use and cover change. Favorable wind characteristics and a lasting drought in 1999 and 2000 may have produced ideal conditions for land surface desiccation, vegetation degradation, and land surface mobility and the occurrence of intense sand- and dust storms in Beijing.