论文部分内容阅读
对沙坡头铁路防护体系内的风沙沉降进行了断面观测,据此分析了沉降速率、粒度组成和物源的时空变化规律。结果显示:防护体系前沿流沙区、防护距离50~300m的植被区和300m以外的植被区风沙沉降速率分别为108.6、17.1kg·m-2·a-1和1.5kg·m-2·a-1。随防护距离增大,沉降颗粒逐渐变细,分选变差,跃移组分含量逐渐减少而悬移组分含量逐渐增大,沉降来源逐渐由前沿流沙区近地面风沙运动颗粒转变为以大气降尘为主的悬移颗粒。年内风沙沉降的高峰期为3—5月,6—8月沉降减弱,9月至次年2月风沙沉降最弱,3个阶段内防护体系植被区月均沉降量分别为0.59、0.10kg·m-2和0.04kg·m-2。3—5月风沙沉降以上风向邻近区域的风蚀起沙为主,6—8月较远源的大气降尘相对增加而上风向邻近区域的风蚀起沙相对减少,9月至次年2月风沙沉降物源以大气降尘为主。
The section observation of sand deposition in the Shapotou railway protection system was carried out. Based on the above analysis, the sedimentation rate, grain size distribution and the spatial and temporal variation of the source were analyzed. The results showed that the sedimentation rate of the aeolian sand in the frontal inflow area of the protection system, the vegetation area with the protection distance of 50 ~ 300m and the vegetation area beyond 300m were 108.6, 17.1 kg · m -2 · a -1 and 1.5 kg · m -2 · a- 1. As the protection distance increases, the sedimentation particles become narrower, the sorting deteriorates, the content of the transition component decreases and the content of the suspended component increases gradually, and the source of the deposition gradually changes from the near-surface wind and sand movement particles in the foreland asthenosphere to the atmosphere Dust-based suspended particles. During the year, the peak of wind-blown sedimentation was March-May. The settlement decreased in June-August and the weakest in September-February of the following year. The average monthly sedimentation of the vegetation in the three phases was 0.59 and 0.10kg · m-2 and 0.04kg · m-2.3-5 months were lower than that of normal rainfall. The dustfall of more remote sources in June-August increased relatively while the wind erosion in the vicinity of the upper reaches was relatively Reduce, September to February next year, the source of sediment deposition in the atmosphere to reduce dust-based.