摘要
新月形沙丘顶部稳定性是风沙地貌学尚未解决的科学问题。研究新月形沙丘的顶部稳定性,对于绿洲边缘风沙运动规律揭示、防沙工程建设和沙区生态环境保护等具有重要的现实意义。选择民勤沙区新月形沙丘,通过测定沙丘各部位风速、风蚀风积和粒度等,分析了新月形沙丘顶部稳定机理。主风向(NW)作用是新月形沙丘最高点与沙脊线重合、沙丘前移和高度降低的过程;反向风(SE)作用是沙丘最高点与沙脊线分离、沙丘背风坡风蚀与沙丘增高的过程。由于研究区以NW风为主,新月形沙丘沿NW-SE方向前移,SE风只能风蚀减缓沙丘背风坡的坡度。人为干预将会阻止或减少从迎风坡向沙丘顶部输送沙量,使得新月形沙丘背风坡尤其是背风坡上部风蚀过程增强,新月形沙丘逐渐过渡为抛物线形沙丘。
The barchans dune top stability mechanism is an unresolved aeolian geomorphology problem. It has important practical significance for revealing oasis fringe sand movement laws, constructing sand pre- vention and control projects, protecting ecological environment to research barchan dune top stability mech- anism. This paper analyzed the stability mechanism of barchan dune top by measuring wind speed, aeolian e- rosion and particle sizeat various parts of the barchan dune in Minqin desert. The results show that during the main direction wind （NW） process the highest point of the barchan dunes coincide with the barchan dune ridges, barchan dunes advance forward and barchan dunes height reduces; during reverse wind （SE） process the highest points of the barchans dunes and barchans dune ridges separate, wind erosion takes place at bar- chans dune leeward slope and barchan dunes height increase. Because NW wind is main wind direction, and barchan dune move along the NW--SE direction, SE wind only can erode and slow down the sand dune lee- ward slope gradient. Artificial intervention will prevent or reduce the sediment delivery capacity from the windward slope to the top of the dune, make wind erosion more significant at the barchan dunes leeward, especially in the upper part of the barchans dune leeward, so barchans dunes gradually change to parabolic dunes.
出处
《中国沙漠》
CSCD
北大核心
2016年第4期871-876,共6页
Journal of Desert Research
基金
国家973前期课题(2014CB460611)
国家自然科学基金项目(41261102)
