北京平原土壤机械组成和抗风蚀能力的分析

土壤遇风起沙是风沙活动产生的最根本原因,它的基本点有二:一是具有足以使砂粒产生运动的一定强度的起沙风;二是土壤颗粒小、质地干燥疏松,具有遇风起沙产生运动的属性。本文分析了北京土壤的机械组成特征和结构性能等。叙述了在永定河边部一些地块的野外风沙观测和沙风洞试验,证实土壤结构性、干松程度、植被覆盖状况是决定土壤抗风蚀性能的三要素。最后,试用不易蚀因子含量评价北京平原土壤的抗风蚀能力。

ANALYSES OF MECHANICAL COMPOSITION AND RESISTANCE TO WIND EROSION OF SOIL IN BEIJNG PLAIN

Sand moving by wind on sandy soil is the primary reason for wind-drif-ting sand movement, and needs two basic conditions: one is intensive windable to carry grains, another is dry, loose soil surface with fine grains.Thepaper analyses the mechanical composition and structure of soil in BeijingPlain, points out that wind erosion and wind sand movement intensivelyoccur in the sandy belt relative to the ancient Yongding River. According tofield observation and tunnel experiments, the author considers that the soilstructure, dryness and tightness as well as vegetation coverage are main fac-tors to determine soil resistance to wind erosion. Finally, an attempt to evaluate soil resistance to wind erosin with antierosion factor content is madeand a sketch of resistance to wind erosion is attached.