在国家林业局磴口荒漠生态站长期监测的基础上,利用多种积沙仪,对乌兰布和沙漠东北缘流动沙丘、油蒿半固定沙丘、白刺半固定沙丘、油蒿固定沙丘、白刺固定沙丘5种典型下垫面近地面(0~100 cm)的风沙流输沙量进行了实地观测和对比分析。结果表明:(1) 输沙率(q)随高度(h)增加呈幂函数(q=ah-b,R2≥0.8409)规律衰减,随风速(v)增大呈幂函数(q=avb,R2≥0.9256)规律增加,42.8%~70.7%的输沙量分布在10 cm高度内,67.6%~90.0%的输沙量分布于30 cm高度内。当地表植被盖度达到40%以上时,输沙率下降至无植被覆盖地表输沙率的6.6%以下,可有效阻止地表风蚀。(2) 沙物质主要由粒径为50~250 μm的细沙和极细沙构成,各高度层风蚀物粒度组成服从单峰态分布,峰值在100~250 μm。随高度增加,风蚀物粒径范围趋于变窄,粒径趋于更细。(3) 起沙风多出现在WSW和NW方向,占全年起沙风的53.19%。风沙流中跃移输沙、蠕移输沙的空间分布在理论上应与风向频率分布基本一致,差异性主要由各方位风的强度和持续时间等因素导致。研究结果可为该区域防沙工程设计提供理论参考。
Based on long time monitoring data at Dengkou Desert Ecology Station and observation data from various of sand traps in 2011, aeolian-sand flow structure at 0~100 cm is analyzed over five typical types of underlying surface which include moving dune, Artemisia ordosica semi-fixed dune, Nitraria tanqutorum semi-fixed dune, Artemisia ordosica fixed dune and Nitraria tanqutorum fixed dune in northeastern margin of the Ulanbuh Desert. The results show: (1) The sand transport rate(q) decreases with the increase of height (h) in power function q=a×h-b(R2≥0.8409), and increases with the increase of wind velocity (v) in power function q=avb, (R2≥0.9256); The sand transport flux in 0-10 cm accounts for 42.8%-70.7%, and the sand transport flux in 0-30 cm accounts for 67.6%-90.0%. When vegetation coverage is 40%, sand transport rate is 6.6% of moving dune with no vegetation cover, and surface wind erosion can be effectively prevented.(2) Sand materials mainly are composed of fine sand and very fine sand (50-250 μm). Wind erosion sand grain size composition at each height follows unimodal distribution, and the peak is between 100-250 μm. With the increase of height, wind erosion sand grain size range become more narrow, and grain size become more fine. (3) The driving-sand wind direction concentrates at WNW and NW accounting for 53.19%. The directional distribution of saltation aeolian-sand flow and creep aeolian-sand flow should be almost the same in theory, and differences are mainly caused by directions of wind intensity and duration.
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