摘要
为比较饱和紫色土坡面片流与细沟流水力学特征并明确其临界水力学特性,进行5个坡度(2°,5°,10°,15°,20°)和3个雨强(30,60,90 mm/h)组合条件下的室内人工模拟降雨试验,在测得坡面片流、细沟流及其转变的临界流速的基础上,计算得到片流、细沟流及其转变的临界水力学参数,包括水深、雷诺数、弗劳德数和达西阻力系数。结果表明:在不同侵蚀阶段,片流流速为0.064~0.151 m/s,细沟流流速为0.175~0.350 m/s,雨强和坡度在不同侵蚀阶段对流速和水深的影响程度存在差异。片流均为层流,<10°坡时,片流为缓流,片流多居缓层流流态;中、大雨强条件下,细沟流均为过渡流,>5°坡时细沟流均为急流,细沟流多为急过渡流流态。片流达西阻力系数与坡度和雨强呈负相关关系,细沟流达西阻力系数与坡度和雨强呈正相关关系。坡面径流由片流转为细沟流的临界流速为0.100~0.165 m/s。流速改变坡面形态,导致细沟侵蚀发生的临界水流流态和水流阻力随坡度和雨强变化的规律不同。研究结果对于认识饱和土壤条件下坡面不同侵蚀阶段径流水力学特性,进一步明确由片流转为细沟流的临界水力条件具有一定参考价值。
In order to compare the hydraulic characteristics of sheet flow and rill flow on saturated purple soil slope and clarify their critical hydraulic characteristics,indoor artificial simulated rainfall experiments were conducted under the combined conditions of five slope gradients(SGs:2°,5°,10°,15°,20°)and three rainfall intensities(RIs:30,60,90 mm/h).On the basis of measuring the velocity of sheet flow,rill flow and critical velocity of shee flow transform to rill flow,the corresponding hydraulic parameters were calculated,including water depth,Reynolds number,Froude number and Darcy resistance coefficient.The results showed that:In different erosion stages,the velocity of sheet flow was between 0.064 and 0.151 m/s and rill flow was between 0.175 and 0.350 m/s.The influence degree of SGs and RIs on velocity and water depth of sheet and rill flow was different.The sheet flow was all laminar and was tranquil when the slope gradient was<10°.The sheet flow was mostly in the state of tranquil laminar flow.The rill flow was transitional under the conditions of moderate and heavy rain and was rapid when the slope gradient was>5°.The rill flow was mostly in the state of rapid transitional flow.The Darcy resistance coefficient of sheet flow was negatively correlated with SGs and RIs,while that of rill flow was positively.The critical velocity of sheet flow transform to rill flow was between 0.100 and 0.165 m/s.The velocity would change the slope shape,resulting in the difference of the critical flow pattern and flow resistance with SGs and RIs.This study is of great significance to understand the hydraulic characteristics of sheet flow and rill flow on saturated soil slope,and to further clarify the critical hydraulic conditions for the sheet flow to rill flow transition.
作者
谭文浩
陈晓燕
陶婷婷
李丹丹
麻力文
孔令勇
TAN Wenhao;CHEN Xiaoyan;TAO Tingting;LI Dandan;MA Liwen;KONG Lingyong(College of Resources and Environment,Southwest University,Chongqing 400716)
出处
《水土保持学报》
CSCD
北大核心
2023年第3期66-72,共7页
Journal of Soil and Water Conservation
基金
国家自然科学基金项目(42177314)
重庆市研究生科研创新项目(CYS21114)。
关键词
片流
细沟流
临界水力条件
饱和紫色土
模拟降雨
sheet flow
rill flow
critical hydraulic conditions
saturated purple soil
simulated rainfall
作者简介
第一作者:谭文浩(1997-),男,湖南宜章人,硕士研究生,主要从事土壤侵蚀研究。E-mail:twh17774969415@163.com;通信作者:陈晓燕(1971-),女,重庆北碚人,教授,博士生导师,主要从事土壤侵蚀与流域治理研究。E-mail:c400716@126.com。
