毛乌素沙地流动沙丘不同沙障组合措施的防风固沙效益评价

Benefit evaluation of wind prevention and sand fixation under the combined measures of sand barrier in mobile dunes in Mu Us sandy land

为了解毛乌素沙地沙柳再生沙障、聚乳酸(PLA)沙袋沙障和草绳沙障配置固沙植物种组合措施下的防风固沙效益,通过对各类组合措施下不同高度处风速、近地表输沙量、障内蚀积形态的测定,对比分析了不同材料、坡位、规格下几种沙障组合措施的防风固沙效益。结果表明:(1)1 m×1 m规格沙柳再生沙障、草绳沙障组合措施下降低近地表风速效能最大,可达80.29%、78.49%,3 m×3 m规格的草绳、PLA沙障组合措施下防风效能仅为58.14%、57.88%;(2)输沙率降低率表现为:沙柳>草绳>PLA,且呈随规格增加而减小的趋势,其中沙柳再生沙障组合措施阻沙效果较稳定,其他2种稳定性较差;(3)各类措施下障内微地形主要受NW~NNW风向控制,不同类沙障材料障内形态特征不同,整体以侵蚀为主,草绳沙障组合措施障内相对侵蚀深度最大,PLA沙障措施下次之,沙柳沙障措施下表现为以-10~5 cm区间侵蚀深度范围为主的弱蚀积状态,但相对侵蚀深度范围均呈随规格增大、坡位增加而减小的趋势。综合分析认为,沙柳再生沙障配以撒播固沙植物种的人工固沙植被体系最为稳定,防风固沙效益最优,为毛乌素沙地较为适宜的流动沙丘沙障促进植被恢复治理技术措施,其余组合措施可视沙障材料获取难易、运输条件以及流沙环境和治理目的适当采用。

The benefits of wind and sand control under the combined measures of sand-fixing plant species with regenerative sand barriers of Salix mongolica,polylactic acid(PLA)sandbags,and straw rope sand barriers in the Mu Us sandy land was studied.The wind speed,near-surface sand transport,and erosion pattern inside the barrier were measured at different heights under various combinations of measures,and the benefits of several sand barrier and combined measures under different materials,slope positions,and specifications were compared and analyzed.The results showed wind speed reduction was highest for the 1 m×1 m S.mongolica regenerative sand barrier and straw rope sand barrier(up to 80.29%and 78.49%).The effectiveness of wind prevention for the 3 m×3 m combination of straw rope and PLA sand barriers was 58.14%and 57.88%,respectively.The reduction rate of sand transport was as follows:S.mongolica>straw rope>PLA,and the trend increased with the specification.The sand-blocking effect of S.mongolica regeneration sand barrier combined measures is more stable,while the other two measures are less stable.The microtopography inside the barrier is mainly controlled by the wind direction from NW to NNW under various measures,and the morphological characteristics varies with the type of sand barrier material.The overall erosion is dominant,and the relative depth of erosion in the barrier is the largest for straw rope sand barriers combination,and the PLA barrier is the next,and the S.mongolica regeneration sand barrier is weakly eroded in the range of-10-5 cm,but the relative depth of erosion decreases with the increase of specification and slope.Comprehensive analysis shows that the artificial sand fixation vegetation system of Salix mongolica sand barrier combined with sowing sand fixation plant species is the most stable,with the best benefit of wind prevention and sand fixation,and is a more suitable mobile sand dune sand barrier in Mu Us sandy land.It is a more suitable technical measure for flowing dune sand barriers to promote vegetation restoration in Mu Us sandy land.The other measures can be appropriately adopted according to the difficulty of obtaining sand barrier materials,transportation conditions,quicksand environment,and control.