柔性植被对地表径流水力特性及侵蚀的影响
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西北农林科技大学 水土保持研究所

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国家自然“坡耕地微地形水力连通性及入渗机理研究”(41771308)


The Impact of Flexible Vegetation on Surface Runoff Hydraulic Characteristics and Erosion
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Institute of Soil and Water Conservation,Northwest Agriculture and Forestry University

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    摘要:

    柔性植被的近地表覆盖对减少径流和侵蚀产量以及调节地表径流水力特性影响的研究较少,本文以流体力学和水力学基本理论为依据,通过5个覆盖度、5个坡度和3个流量组合条件下的室内放水试验,系统研究了柔性植被覆盖条件下的侵蚀规律以及水动力学特征。结果表明:(1)侵蚀量分布随坡度增加呈先上升后下降的趋势,流量在高坡度下对侵蚀过程的影响更为显著;(2)随着柔性植被覆盖度增加,以50%覆盖度为分界线,侵蚀量先降低后增加;(3)平均流速v随覆盖度的增加而减小,下降趋势随覆盖度增加由急变缓,Fr值变化趋势与平均流速相似;阻力系数f与覆盖度呈线性正相关,随坡度升高,阻力系数值逐渐降低;而雷诺数Re对土壤侵蚀的影响比Fr、v和f更敏感。(4)随植被覆盖度的增加,形态剪切力增大(颗粒剪切力减小),形态剪切力在总剪应力的变化中起决定性作用,总剪切力与植被覆盖度呈正相关。研究可为坡面流植被侵蚀规律奠定了一定的理论基础,促进明渠水力学理论在坡面水流方面的扩展。

    Abstract:

    There is limited research on the influence of near-surface coverage of flexible vegetation on reducing runoff and erosion yields, as well as on regulating the hydraulic characteristics of surface runoff. Based on the principles of fluid mechanics and hydraulics, this study conducted indoor drainage experiments under five coverage levels, five slopes, and three flow rate combinations. The erosion patterns and hydrodynamic characteristics under flexible vegetation cover conditions were systematically investigated. The results indicate: (1) The distribution of erosion volume initially rises and then falls with increasing slope, with flow rate having a more significant impact on the erosion process at higher slopes. (2) As the coverage of flexible vegetation increases, erosion volume decreases initially and then increases, with 50% coverage as the turning point. (3) The average flow velocity (v) decreases with increasing coverage, and the decreasing trend becomes less steep as coverage increases. The variation trend of the Froude number (Fr) is similar to that of the average flow velocity. The resistance coefficient (f) is linearly correlated with coverage, and with increasing slope, the value of the resistance coefficient gradually decreases. Reynolds number (Re) is more sensitive to soil erosion than Fr, v, and f. (4) With increasing vegetation coverage, morphological shear force increases (particle shear force decreases), and morphological shear force plays a decisive role in the variation of total shear stress, which is positively correlated with vegetation coverage. This study lays a theoretical foundation for understanding the erosion patterns of vegetated slopes, and promotes the extension of open channel hydraulics theory in slope surface flow.

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  • 收稿日期:2023-10-09
  • 最后修改日期:2024-01-11
  • 录用日期:2024-01-11
  • 在线发布日期: 2024-04-29
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