不同处理下油松枯落物减流减沙效应试验研究

Effect of Runoff and Sediment Reduction of Different Treatment by Litter of Pinus tabulaeformis

森林枯落物对坡面土壤侵蚀过程发挥着重要的调控作用,但其控制效应仍待明确。采用室内大型土槽及人工模拟降雨试验探讨油松枯落物的不同铺设方式对坡面产流产沙的影响,试验在4种雨强(30,60,90,120 mm/h)和油松枯落物的3种铺设方式(裸坡对照、枯落物直接铺设和枯落物隔网铺设)下进行,设置枯落物隔网铺设方式来研究枯落物降低雨滴动能减少击溅侵蚀作用,设置枯落物直接铺设方式来研究枯落物增大地表粗糙率阻滞拦截作用。结果表明:(1)枯落物存在使坡面初始产流时间延长2.3~5.5倍,且枯落物隔网铺设较直接铺设初始产流时间更长。(2)2种枯落物覆盖坡面与裸土坡面相比,枯落物减小坡面径流流速47.9%~62.3%,雨强越小,枯落物减弱径流流速作用越明显。(3)枯落物显著增加入渗并减小径流,在雨强较小时作用更加明显。(4)枯落物可减少径流泥沙75%以上,直接铺设减沙更加明显,这主要是由于枯落物增大地表糙度减小流速。研究结果为植被坡面土壤侵蚀模型建立提供一定理论基础,为面向水土流失防控的植被构建提供一定科学依据。

Forest litter plays an important role in controlling soil erosion on slopes,but its control mechanism remains to be clarified.In this study,the effects of different litter cover on runoff and sediment yield on slopes were investigated by laboratory large-scale soil trough and artificial simulated rainfall test.The experiment was conducted under four rainfall intensities(30,60,90,120 mm/h)and three litter mulching treatments(bare slope control,direct laying of litter and net laying of litter).Setting up the net laying of litter,which is in order to study on litter reducing splash erosion with reducing kinetic energy of raindrops.Setting up the direct laying of litter,which is in order to study on blocking interception of litter increasing ground roughness.The results indicated that:(1)The initial runoff generation time of slopes was prolonged by 2.3~5.5 times with the existence of litter,and the net laying of litter was longer than that of direct laying.(2)Compared with bare soil slope,litter decreased the runoff velocity by 47.9%~62.3%,and the smaller the rainfall intensity,the more obvious the effect of litter on reducing the runoff velocity.(3)Litter significantly increases infiltration and decreases runoff,and the effect is more obvious when rainfall intensity is small.(4)litter can reduce runoff and sediment by more than 75%,and direct laying is more obvious,mainly because litter increases surface roughness and reduces flow velocity.This study provides a theoretical basis for the establishment of soil erosion model on vegetation slope,and provides a scientific basis for the construction of vegetation for soil erosion prevention and control.