风蚀水蚀交错区小流域的风沙输移特性及其影响因素

通过对河北坝上地区典型小流域风沙输移特性及其影响因素的研究，得到了风蚀水蚀交错区风沙流的几方面典型特征，主要包括：（1）高效农田、草地、灌木丛3种不同下垫面风沙流风速随高度增加均呈递增趋势，其垂向分布与下垫面的性质密切相关；（2）3种不同下垫面输沙量垂向分布差异明显，其中高效农田的输沙量与垂直高度有较好的负指数函数关系；（3）高效农田风蚀物中粒径在0．1～0．075mm之间的极细颗粒和粒径在0．075～0．019mm之间的粉砂颗粒的含量较高，占输沙总量的80％以上，说明近地表层沙粒的运动以跃移为主；（4）输沙量与下垫面特性密切相关，植被盖度越大，输沙量越小；（5）气象因子和人为因子等环境因子对小流域风水两相侵蚀具有决定性的影响。

Wind-Sand Flow Transportation Characteristics and Effect Factor of Typical Valley in Wind-Water Erosion Crisscross Region

Studying wind-sand flow transportation and effect factors of typical valley in Bashang area of Hebei Province,several characteristics are obtained primarily involving:(1)Wind speed increased by degrees with increased height under the three different surface conditions including high-efficiency farmland,meadow and bosk,and vertical distributing correlated nearly with character of surface conditions;(2)Vertical distributing of transportation sediment was obviously different under the three different surface conditions,and the total sediment on high-efficiency farmland had a well relation with vertical height by a negative exponential function;(3)The particle-size distribution analysis of the windblown sediment collected from individual layers showed that the proportions of fine particles(diameter 0.10.075 mm) and silt and clay particles(diameter 0.075~0.019 mm) were very high and accounted for a considerable higher proportion over 80%,suggesting that the motion of sand particles near the surface is dominated by saltational fashion;(4)The total sediment correlated nearly with character of surface conditions and decreased with increased vegetative cover;(5)Environmental complications including meteorological and factitious factors had crucial efforts on wind-water erosion of typical valley.