冲刷条件下坡面水流速度与产沙关系研究
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* 引进国外杰出人才基金(982602);国家自然科学基金项目(40171062);中国科学院知识创新重要研究方向项目(KZCX3SW422)


RELATIONSHIP BETWEEN VELOCITY OF SLOPE FLOW AND SEDIMENT GENERATION DURING EROSION
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    摘要:

    在冲刷条件下,通过5种坡度下的水流速度和泥沙含量测量,发现两者存在同步的关系;水流速度的变化与细沟的发育存在明显的对应关系.在细沟开始发育时,水流速度逐渐增大;当细沟基本形成后,水流速度减小并平稳.水流速度是影响坡面产沙的主要原因,在低坡度时,细沟发育较慢,产沙量较少,但坡度在10°~20°之间产沙量相差不大,到25°时的产沙量反而比20°的还少,出现了人们观察到的临界坡度.根据坡面特性,分析水流速度和泥沙含量之间关系使土壤侵蚀的临界坡度得到比较合理的解释.在大于临界坡度时,水流速度一开始很快增大,所冲刷的泥沙量并不比坡度小的少;跌坎容易形成,且比较深,从而使水流速度减小.但细沟在较短的时间内发育完成,水流速度也随之减小,泥沙含量降低;从而使在一定时间之后,大于临界坡度时所冲刷的累积泥沙含量较少.通过用电解质脉冲法测量水流速度解释了坡面冲刷侵蚀过程中的一些现象,若进一步测量其时空分布,有可能更深入地揭示其侵蚀机理,为建立合理的土壤侵蚀预报模型提供准确参数.

    Abstract:

    Under erosion conditions, velocities and sediment concentrations in water flows running down five slopes different in gradient were measured.Results show that sediment concentration changes with velocity.The former is positively correlated to rill development.At the beginning of rill development, velocity of the flow increases gradually, and when rills come basically into shape, it decreases and then levels off.The velocity of the flow is the main factor causing production and transference of sediment.When the gradient of a slope is low, rills develop slowly and little sediment is produced.The production of sediment does not differ much when the slope varies between 10°~20°.When the gradient is at 25°, however, even less sediment is produced than 20°indicat ing a critical gradient existing between 20°and 25°.Based on the characteristics of a slope, analysis of the relationship between velocity of the flow and sediment concentration therein may help explain reasonably the critical gradient of the slope.When the gradient of a slope is bigger than the critical value, velocity of the flow increases at the beginning, bringing down sediment not less than that on the slope with gradient smaller than the critical value.In this case, a deep sink is more likely to form, thus reducing the velocity of the flow.Rills, however, complete their development within a short period of time, causing the velocity of the flow and sediment concentration therein to decline.As a result, the cumulated sediment eroded within a certain time from the slope with gradient bigger than the critical value is less.The measurement of velocity with the electrolyte pulse method explains some phenomena of the erosion process.If the spatio-temporal distribution of velocity is further measured, the study may likely go deep enough to reveal mechanism of erosion and provide more accurate parameters for establishment of a rational model for prediction of soil erosion.

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夏卫生,雷廷武,张晴雯,潘英华,赵军.冲刷条件下坡面水流速度与产沙关系研究[J].土壤学报,2004,41(6):876-880. DOI:10.11766/trxb200309020606 Xia Weisheng, Lei Tingwu, Zhang Qinwen, Pan Yinhua, Zhao Jun. RELATIONSHIP BETWEEN VELOCITY OF SLOPE FLOW AND SEDIMENT GENERATION DURING EROSION[J]. Acta Pedologica Sinica,2004,41(6):876-880.

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  • 收稿日期:2003-09-02
  • 最后修改日期:2004-06-15
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  • 在线发布日期: 2013-02-25
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