生物埂不同植物类型下土壤分离水力学特性研究

【目的】探明川中丘陵区六棱型预制网格式生物埂不同植物类型下土壤分离能力与细沟水流水力学特性间的数学关系。【方法】野外采集生物埂坡面麦冬和韭菜2种植物根系下的原状土样(直径10 cm),以单一网格式生物埂裸坡为对照,建立室内模拟细沟(长4 m,宽0.12 m,深0.1 m),在3个坡度(15°、20°、25°)、5个流量(39.86、59.98、79.67、100.45、121.16 L/min)的完全组合条件下进行冲刷试验,探讨水力学参数(雷诺数Re、弗汝德数Fr、Darcy-Weisbach阻力系数f、曼宁系数n)与土壤分离能力间的数学定量关系。【结果】1)不同植物类型下生物埂土壤分离能力表现为麦冬(均值2.24 kg/(s·m^2))>对照(均值1.34 kg/(s·m^2))>韭菜(均值1.09 kg/(s·m^2))。2)土壤分离能力与水流流态与流型参数之间均呈幂函数正相关,其中与雷诺数Re呈极显著幂函数正相关(均值R^2=0.75,P<0.01),与弗汝德数Fr呈显著幂函数正相关(均值R^2=0.27,P<0.05)。3)土壤分离能力与水流阻力参数间的关系主要呈负相关,其中与Darcy-Weisbach阻力系数f呈显著幂函数负相关(均值R^2=0.36,P<0.05),而与曼宁系数n之间的幂函数关系不显著(均值R^2=0.16,P>0.05)。【结论】与麦冬相比,韭菜增强土壤抗侵蚀能力的效果更显著。水力学参数中,水流流态流型参数中雷诺数Re预测土壤分离能力的效果相对较好,水流阻力参数中以Darcy-Weisbach阻力系数f效果较好,总体比较,以雷诺数预测土壤分离能力效果最好。

Coupling of soil detachment and hydraulic parameters under the terrace banks planted with different plants

【Objective】The article aimed to clarify the relationships between soil detachment capacity(Dc)and hydraulic parameters,including Reynolds number(Re),Froude number(Fr),Darcy-Weisbach coefficient(f)and Manning coefficient(n).Method]The undisturbed soil samples(10 cm in diameter)under terrace banks in hexagonal prefabricated net format with different plants of Ophiopogon japonicus,Allium tuberosum and bare land were collected in situ respectively.we simulated the rill morphology and then conducted the flume scouring experiments in the laboratory(4 m long,0.12 m wide,0.1 m height).Flume scouring experiments were carried out under the combinations of 3 slopes(15°,20°,25°)and 5 flow rates(39.86,59.98,79.67,100.45,121.16 L/min)with 3 replicates(i.e.,a total of 135 scouring experiments).【Result】Soil detachment capacities under terrace banks with different plants ranked as Ophiopogon japonicus2.24 kg/(s·m^2)]>bare land1.34 kg/(s·m^2)]>Allium tuberosum1.09 kg/(s·m^2)].Dc showed positive power relationships with flow regime,which had extremely significantly positive power relationship with Re(R^2=0.75,P<0.01),moderately significantly positive power relationship with Fr(R^2=0.27,P<0.05).Dc exhibited negative relationships with flow roughness,and had significantly negative power relationship with f(R^2=0.36,P<0.05),while had no significant relationship with n(R^2=0.16,P>0.05).【Conclusion】Allium tuberosum could enhance soil erosion resistance more effectively in comparison to Ophiopogon japonicus.For the flow regime,Reynolds number showed the better relationship with Dc,and for the flow roughness,Darcy-Weisbach coefficientpresented the better correlations with Dc,respectively.In general,Reynolds numberwas the best hydraulic parameter to predict Dc in this study.