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植被是控制土壤侵蚀的关键因子,研究植被不同部位的减沙效益及机理对于水土保持、植物保护和恢复具有指导意义。以白三叶(Trifolium repens L.)和红壤为实验对象,采用人工模拟降雨的方式,在坡度15°和雨强60、120、180 mm·h~(-1)条件下,测定完整植株坡面、根系坡面和裸坡的产流产沙过程和流速,研究草本植物完整植株、冠层、根系在红壤坡面的减沙效应及其对坡面径流水动力学参数的影响。研究结果表明,盖度为85%的白三叶平均减沙效益为97.3%,根系、冠层的平均减沙效益分别为66.3%、31.0%,根系的减沙效益显著高于冠层。植被能够降低径流含沙量,尤其是降雨初期的径流含沙量。植被能够降低38.6%的坡面径流流速,其中冠层的平均减速效益为31.2%,根系的平均减速效益为7.3%,冠层的减速效益远大于根系。植被对坡面径流雷诺数影响较小,能够降低径流的弗劳德数,缓解径流流态,但坡面径流都为层流-缓流形态。植被能够显著增加坡面径流的达西-韦斯巴赫阻力系数,冠层的平均增阻效益为402.4%,根系的增阻效益为33.0%。随着雨强的增大,植被的增阻效益降低。白三叶具有良好的调控坡面侵蚀的能力,其中冠层主要通过对坡面径流的流速和阻力的影响来减少坡面侵蚀,而根系的减沙效益要大于其减速和增阻效益。植被调控坡面侵蚀的机理十分复杂,其中根系的减蚀机理需要进一步深入研究。
Vegetation is the key factor to control soil erosion. It is instructive to study the benefits and mechanisms of sediment reduction in different parts of the vegetation for soil and water conservation, plant protection and restoration. Taking Trifolium repens L. and red soil as test objects, the artificial plantation rainfall was used to measure the whole plant slope at the slope of 15 ° and the rainfall intensity of 60,120,180 mm · h ~ (-1) Runoff process and flow rate on the slope, slope and bare slope, and the effects of intact plant, canopy and root system on red soil slope and its effect on runoff hydrodynamic parameters were studied. The results showed that the average sediment yield of white clover with the coverage of 85% was 97.3%, the average sediment yield of roots and canopy was 66.3% and 31.0% respectively, and the sediment yield of the root system was significantly higher than that of the canopy. Vegetation can reduce runoff sediment concentration, especially in the early runoff sediment concentration. Vegetation can reduce the runoff velocity by 38.6%. The average canopy deceleration efficiency is 31.2%, the root mean deceleration efficiency is 7.3%, and the canopy deceleration effect is much larger than the root system. Vegetation has little effect on the runoff Reynolds number, which can reduce the Froude number of runoff and alleviate the runoff flow, but the runoff of the runoff is laminar flow - slow flow. Vegetation can significantly increase the Darcy-Weissbach resistance coefficient of runoff. The average canopy drag efficiency is 402.4% and the root drag reduction is 33.0%. With the increase of rainfall intensity, the efficiency of vegetation resistance decreases. White clover has a good ability to control slope erosion, of which the canopy reduces slope erosion mainly through the effect of flow velocity and resistance on runoff, while the runoff benefit of the root system is greater than its deceleration and drag reduction. The mechanism of vegetation-controlled slope erosion is very complicated, and the mechanism of root erosion should be further studied.