摘要
川中丘陵紫色土在长期耕作侵蚀与水蚀的交互作用下侵蚀严重,在不同地形条件下紫色土耕作侵蚀坡面在二者相互作用的内在机理,以及水力学特征随坡度的变化规律尚不明晰。本文选取四川盆地典型紫色土坡地土壤为研究对象,以10 m^(2)土槽坡面坡顶裸露2 m^(2)母岩代表受耕作侵蚀严重的坡面(TE),以坡顶未发生母岩裸露作为对照坡面(CG),设计5种不同坡度(5°、10°、15°、20°和25°)坡面,在室内人工降雨大厅进行60 min强度为90 mm·h^(-1)的模拟降雨。试验结果表明:(1)当坡度从5°逐渐增加到25°时,TE坡面较CG坡面累计产沙量分别增加了17.73%、49.91%、83.95%、57.70%、29.56%,在坡度为15°时增长比例最大。(2)TE和CG坡面平均流速和弗劳德数随着坡度增加而增加,阻力系数和雷诺数随着坡度增加而减小。与CG相比,TE坡面的流速、弗劳德数和雷诺数均显著增加,而阻力系数在10°~20°坡面显著减小。(3)在TE和CG坡面上,产沙速率和流速、弗劳德数均呈显著正相关关系,产沙速率和阻力系数呈显著负相关关系,产沙速率与雷诺数相关性不明显,拟合结果表明平均流速可以很好地预测坡面产沙速率和水力学变化趋势。研究显示不同坡度条件下耕作侵蚀均加剧了坡面水蚀的发生,15°可能是耕作-水复合侵蚀坡面产沙的临界坡度。本研究结果不仅丰富了耕作侵蚀对水蚀影响的理论,也为川中丘陵紫色土区土壤侵蚀防治提供了科学依据。
The purple soil in the hilly area of central Sichuan basin of China is seriously affected by the interaction of long-term tillage erosion and water erosion,and the internal mechanism of the interaction between the two erosions and the variation law of hydraulic parameters with slope under different topographic conditions is still unclear.In this study,purple soil in the Sichuan Basin was selected as the research object.Two test plots of 10 m^(2)in the rainfall simulation laboratory,one with bare bedrock areas of 2 m^(2)in the summit positions and the other with no bedrock exposure were chosen for tillage erosion(TE)and the control group(CG)respectively.Five different slope gradients(5°,10°,15°,20°and 25°)were designed to perform rainfall simulation experiments with 90 mm·h^(-1)rainfall intensity for 60 minutes.The results show that:(1)Compared with CG,as the slope gradually increased from 5°to 25°,TE cumulative sediment yield increased by 17.73%,49.91%,83.95%,57.70%and 29.56%,with the growth rate being the largest at 15°.(2)For TE and CG,the average flow velocity and Froude number increased with an increase in slope gradient,whereas resistance coefficient and Reynolds number gradually decreased with an increase in slope gradient.Compared with CG,TE flow velocity,Froude number,and Reynolds number increased significantly,yet the resistance coefficient decreased significantly for slope gradients ranging from 10°to 20°.(3)Sediment yield rate was positively correlated with flow velocity and Froude number,but it was negatively correlated with resistance coefficient.There was no significant correlation between sediment yield rate and Reynolds number.The fitting results indicate that the average flow velocity could well predict sediment yield rate and the trend of hydraulics.The findings confirmed that tillage erosion would aggravate the occurrence of water erosion.Observation also suggested that 15°was the critical slope gradient of sediment yield under tillage-water joint erosion.This study not only support
作者
侯宁
王勇
赵虎
张校棱
梁心蓝
HOU Ning;WANG Yong;ZHAO Hu;ZHANG Xiaoling;LIANG Xinlan(College of Water Conservancy and Hydropower Engineering,Sichuan Agricultural University,Ya an 625014,Sichuan,China;College of Forest,Sichuan Agricultural University,Chengdu 611130,China)
出处
《山地学报》
CSCD
北大核心
2021年第4期495-505,共11页
Mountain Research
基金
国家自然科学基金(41701324)
四川省教育厅资助科研项目(17ZB0343)。
关键词
紫色土
坡度
模拟降雨
产流产沙
水力学参数
四川盆地
purple soil
slope gradient
rainfall simulation
runoff and sediment yield
hydraulic parameter
the Sichuan Basin
