包兰铁路沙坡头段防护体系内的风沙沉降规律  

Aeolian Deposition in the Protective System of Shaopotou Section of the Baotou-Lanzhou Railway

作　　者：张加琼[1] 张春来[1] 吴晓旭[1] 李君丞 

机构地区：[1]北京师范大学地表过程与资源生态国家重点实验室/防沙治沙教育部工程研究中心,北京100875 [2]成都市金牛区环境保护局,四川成都610036

出　　处：《中国沙漠》2014年第1期16-22,共7页Journal of Desert Research

基　　金：国家自然科学基金项目(41171004)资助

摘　　要：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^-2和1．5kg·m^-2·a^-2。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O．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。This paper investigated spatial and temporal distribution of the aeolian deposition in the protective system of Shapotou section of Baotou-Lanzhou Railway and analyzed the deposition rate, grain size composi- tion and material source. The results show that the deposition rate is 108. 6, 17.1kg·m^-2·a^-2 and 1.5kg·m^-2·a^-2 in the front moving sand area, the area of protective distance between 50 m and 300 m and the area of protective distance larger than 300 m in the protective system, respectively. The grain size of the aeolian deposition increases along the cross section and the sorting gets worse. The content of suspension particles increases while that of the saltation particle decreases with undulation caused by the fixed and semi- fixed dunes in the protective system. The aeolian deposition concentrates from March to May and reduces from June to August, whereas the other months experience the least deposition. The monthly aeolian depos- its in the protective system during these three durations are 0.59, 0.1 kg. m-2 and 0.04 kg. m-2, respec- tively. The main source of the aeolian deposition from March to May is the saltation sands from the adjacent upwind moving sand area. Dust fall increases relatively and the sands from the adjacent upwind moving sand area reduce from June to August. From September long distance areas becomes the main source of the to February of the next year, dust fall transported from aeolian deposition.

关 键 词：防护体系 风沙沉降 粒度 物源 时空变化 

分 类 号：X169[环境科学与工程—环境科学]