模拟降雨条件下第四纪红黏土坡面侵蚀过程

通过室内模拟降雨试验,分析雨强和坡度对第四纪红黏土坡面侵蚀过程的影响,揭示南方红壤低山丘陵区第四纪红黏土坡面侵蚀机理。根据研究区地形和降雨特点,设计坡度10°,15°,20°,雨强1.0,1.5,2.0mm/min,研究两者对坡面侵蚀过程的影响。结果表明:(1)坡面初始产流时间随着坡度和雨强的增大而逐渐减小;同一雨强下,径流系数大小为20°15°10°。(2)不同试验处理条件下,坡度由10°增加到20°,坡面累积产沙量增加0.46~1.98倍;降雨强度由1.0mm/min增加到2.0mm/min,坡面累积产沙量增加1.37~3.85倍。(3)1.0,1.5mm/min雨强条件下,坡面侵蚀泥沙以0.25mm水稳性团聚体占优,2.0mm/min雨强条件下,坡面侵蚀泥沙0.25mm水稳性团聚体为主。(4)坡度与雨强对坡面径流系数、侵蚀率和累积产沙量影响极显著(P0.01),坡面累积径流量和累积产沙量构成幂函数模型。研究结果为揭示坡度与雨强对第四纪红黏土坡面侵蚀过程的作用机理提供参考。

Study on Processes of Erosion on Hillslopes of Quaternary Red Clay Under Simulated Rainfall

The effects of rainfall intensity and slope on erosion process for quaternary red soil was analyzed through indoor simulated rainfall test, and the test reveal the mechanism of slope erosion for quaternary red clay in hilly area of South China. According to the characteristics of topography and precipitation in the study area, we designed slopes of 10°, 15°, 20°, and rainfall intensity of 1.0, 1.5 and 2.0 mm/min to explore the influence of rainfall intensity and slope on the erosion process. The results showed that:(1) The initial slope runoff time decreased with the increase of slope and rainfall intensity; under the same rainfall intensity, the runoff coefficient was 20° > 15° > 10°; (2) While slope degree increased from 10° to 20°, the total amount of erosion and sediment yield increased by 0.46~1.98 times on the slope; when the rainfall intensity increased from 1.0 mm/min to 2.0 mm/min, the cumulative slope sediment yield increased by 1.37~3.85 times; (3) Under the condition of 1.0 and 1.5 mm/min rain intensity, the sediment yield on slope was dominated by <0.25 mm water-stable aggregates, and the water stability of > 0.25 mm was dominated by the slope erosion under the rainfall intensity of 2.0 mm/min; (4) The effects of slope and the rainfall intensity on runoff coefficient, erosion rate and cumulative sediment yield were significant (P<0.01),and the relationship between runoff and sediment yields could be described by power function. The results provide reference to reveal the mechanism of slope erosion in the quaternary red clay.