苔藓结皮对土壤风蚀影响的风洞试验和模拟

Effect of moss crust coverage and spatial distribution on soil wind erosion using wind tunnel experiments and simulations

生物结皮在干旱半干旱地区土壤风蚀防控中发挥着重要作用。明确生物结皮对土壤风蚀的影响,对量化风蚀预报模型中的生物结皮因子、提高模型预测风蚀的准确性和可靠性具有重要意义。本研究以苔藓结皮为例,对比了风洞试验和单次事件风蚀评估模型(SWEEP)模拟的风蚀速率与输沙率的差异,分析了苔藓结皮盖度和空间分布对土壤风蚀的影响。结果表明:(1)风蚀速率和输沙率均随结皮盖度的增加而减小,尤其是在较大风速下(15 m·s^(-1)),当结皮盖度从10%增加到80%时,风洞试验的平均风蚀速率和输沙率分别减小了98.3%和99.3%,SWEEP模拟的结果分别减小了93.2%和78.9%。(2)相同结皮盖度下,苔藓结皮分布于上风向区域时土壤风蚀速率和输沙率最小,斑块状分布次之,分布于下风向区域时最大。(3)对比风洞试验和SWEEP模拟结果,不同结皮盖度下SWEEP模拟的风蚀速率和输沙率大多显著(P<0.05)高于风洞试验结果。未来的研究应在风蚀预报模型中构建生物结皮因子影响风蚀速率的定量表达,以提高模型预报风蚀的准确性。

Biological soil crusts(biocrusts)play an important role in wind erosion control in arid and semiarid regions.It is of great significance to clarify the influence of biocrusts on soil wind erosion and to quantify biocrust factors in wind erosion prediction models to improve the accuracy and reliability of wind erosion prediction.This study analyzed differences in wind erosion and sediment transport rates when affected by the coverage and spatial distribution of moss crust by combining wind tunnel experiments and SWEEP simulations.The results showed that:(1)Both the wind erosion and sediment transport rates decreased with increasing crust coverage,particularly at high wind speeds(15 m·s^(-1)).The average wind erosion and sediment transport rates decreased by 98.3%and 99.3%,respectively,in wind tunnel experiments when crust coverage increased from 10%to 80%,while they decreased by 93.2%and 78.9%,respectively,according to the SWEEP simulation.(2)The wind erosion and sediment transport rates were relatively low when moss crusts were distributed in the upwind area of the experimental trays,followed by patchily distributed moss crusts,while they were the most severe when moss crusts were located in the downwind area under conditions of the same crust coverage.(3)Compared with the results of wind tunnel experiments and SWEEP simulations,the wind erosion and sediment transport rates based on the SWEEP simulation under different crust coverages were significantly(P<0.05)larger compared to those based on the wind tunnel experiments.In order to improve the accuracy of wind erosion prediction models,a quantitative expression of the effect of biocrust factors on wind erosion rates should be constructed in future research.