人工模拟降雨条件下坡面产沙规律及侵蚀泥沙颗粒特征研究

Law of Sediment Production and Characteristics of Eroded Sediment on Slope Based on Simulated Rainfall

利用室内模拟降雨试验,研究了坡面产沙规律及其与径流的相关关系,并对比分析了侵蚀泥沙与原土壤的颗粒特征。结果表明:1产流时间受降雨强度与坡度共同影响,降雨强度和坡度越大,产流时间越短,随降雨强度增加坡度对产流时间的影响越加明显。2不同降雨强度作用下,产沙量(4 min产沙量)均随降雨历时的增加呈现先增加后减少的趋势,但峰值不同,降雨强度越大峰值越大。3累计产沙量与累计径流量呈显著的幂函数关系,可用方程y=AxB来表达,相关系数R2均大于0.986,达极显著水平,系数A随降雨强度和坡度的增加而减小,系数B受降雨强度和坡度的影响无明显规律性变化。4不同降雨强度作用下的侵蚀泥沙颗粒级配不同,与原坡面土壤颗粒级配的差异程度表现为1.2 mm/min<0.8 mm/min<0.5 mm/min,随着降雨强度的减小,侵蚀泥沙中<0.01 mm颗粒的相对含量有所增加,>0.01 mm颗粒的相对含量减少,并且降雨强度越小,这种变化程度越明显。

The paper studied law of sediment production,the correlation between the law and runoff,and analyzed the particle characteristics of eroded sediment and original soil through indoor simulated rainfall tests. The outcomes show that a) the runoff time is effected by both rainfall intensity and slope,the greater the rainfall intensity and slope is,the shorter the runoff time will be. The influence of slope to the runoff time will be more obvious along with the increase of rainfall intensity; b) under the different actions of rainfall intensity,the sediment yield( in 4min) shows the trend of increase first and then decrease along with the increase of rainfall duration. The greater the rainfall intensity is,the greater the peak value will be; c) the accumulated sediment yield and accumulated runoff show remarkable power function relationship. It can be expressed by y = AxB,the correlation coefficient R2≥0. 986,reaching a significant level. The coefficient A decreases along with the increase of rainfall intensity and slope and the coefficient B has no significant changes with the effects of rainfall intensity and slope and; d)the particle size distribution of eroded sediment is different under the different rainfall intensity. Comparing with the original soil on the slope,the degree of difference can be shown as 1. 2mm /min < 0. 8mm / min < 0. 5mm /min. Along with the decrease of rainfall intensity,the relative content of < 0. 01mm grain in the eroded sediment is slightly increased and the content of > 0. 01mm decreased. This degree of changes is more obvious with the smaller rainfall intensity.