黄土坡面细沟发育过程及侵蚀产沙特征研究

A Study of Rill Evolution Process and Sediment Yield Characteristics on Loess Slope

研究细沟发育及其产沙特征对细沟侵蚀预报模型至关重要。采用室内纯净水模拟降雨试验的方法,在不同坡度(10°,15°,20°,25°)和不同雨强(1.5,2.0mm/min)条件下,研究了细沟的发育过程,并讨论分析各发育阶段产沙特征及其影响因素。结果表明,根据坡面含沙量与细沟形态的变化特征,细沟侵蚀过程可划分为面蚀、细沟雏形、细沟发育、细沟调整4个阶段;各阶段的侵蚀量占坡面总侵蚀量的比例均不同,其中细沟发育阶段最大,约占总侵蚀量的40%;各阶段持续时间随着坡度的改变而改变;雨强增大对细沟间与细沟流速有促进作用,细沟流速为细沟间流速的0.75～1.77倍;坡面侵蚀速率受雨强与坡度的影响很大,在同一坡面上细沟流速与侵蚀速率的关系更紧密,但二者的定量关系有待进一步探索。

A study of rill evolution process and sediment yield characteristics is important for rill erosion prediction model.At different slopes（10°,15°,20°and 25°）and different rainfall intensities（1.5and 2.0mm/ min）,the indoor simulated rainfall experiment with pure water was conducted to study the specific rill evolution process.The relationships between rill development stages and influencing factors were discussed.According to the characteristics of sediment concentration and rill form,the rill development process was classified as the four states of surface erosion,initial rill form,rill development and rill adjustment.Results showed that the proportions of sediment yield to the total erosion were different for different stages.The proportion for the rill development was the largest,about 40% of the total erosion.The duration for each stage changed with slope.Increase in rainfall intensity had a promotion role in rill and interrill flow velocities.Rill flow velocity was 0.75～1.77times of interrill velocity.Rainfall intensity and slope had a great influence on erosion rate.The relationship between flow velocity and erosion rate was closer on the same slope,but the quantitative relationship should be explored further.