黄土高原地区沙尘暴形成的自然地理因素:Ⅱ多元回归分析与地带性特征

Physico-Geographical Factors for Formation of Sand-Dust Storms in Loess Plateau Region: Multiple Regression Analysis and Zonality

以黄土高原地区227个县的资料为基础,运用逐步回归的方法,建立了年均沙尘暴日数与影响因子之间的多元回归方程。黄土高原地区沙尘暴的分布具有一定的地带性。从西北向东南,年降水量逐渐增加,气候由干旱、半干旱向半湿润过渡。地表物质由风成沙、沙黄土向典型黄土和粘黄土过渡,天然植被类型由干旱荒漠、干草原、森林草原、草原森林向落叶阔叶林过渡,自然地理因子的地带性分异导致了沙尘暴的频率按同一方向递减。建立的回归方程表明,地表物质的抗蚀性对沙尘暴的影响较大,年降水量次之,大风日数居第三。通过合理的人类活动增加地表的抗蚀性,可以减低沙尘暴的发生频率。

Based on the data from 227 counties in the Loess Plateau region and using regression method, a multiple regression equation has been established between the frequency of sand-dust storm and the influencing factors. The distribution of frequency of sand-dust storms exhibits some zonality in the study area. In the northwest to southeast direction, annual precipitation increases, leading to transition from arid, semi-arid to sub-humid climates. In the same direction, surface material varies from eolian sand, sandy loess, to typical loess and clayey loess; vegetation from desert, steppe, steppe with forest, forest with steppe to broad-leave deciduous forest. The above zonal differentiation in physico-geographical factors results in a decline in frequency of sand-dust storm in the same direction. The multiple regression equation based on standardized data indicates that the contribution made by the erosion resistance of surface material is the largest, and that by annual precipitation is the second, and that by annual strong wind days is the third. Hence, the frequency of sand-dust storms may be reduced to some degree by measures to increase the erosion resistance of land surface, e.g., transforming cultivated land to grassland in arid and semi-arid climate zones.