缓坡面细沟发育过程及水沙关系的室内试验研究

摘要

In this paper, the indoor simulated rainfall experiment with pure water was conducted to study rill evolution process and relationship between runoff and sediment for Yangling soil and Ansai soil under the fixed slope gradient (10°) and two rainfall intensities (1.5 mm/min, 2.0 mm/min). Results showed that rill was evolved from a series of step-down floor which were parallel to each other and distributed with line at slope surface direction. Yangling soil produced the rill with a small rainfall intensity, and Aasai soil produced the rill only with larger rainfall intensity. The change rule of sediment concentration and erosion rate and the moment of forming step-down floor and rill have good consistency, and the increasing rainfall intensity has little influence on sediment concentration and erosion rate for Yangling soil, however, sediment concentration and erosion rate for Aasai soil could increase rapidly and exceed Yangling soil with the emergence of rill when the rainfall intensity was larger. For Yangling soil, the rill could not cause obvious change of sediment concentration and erosion rate, however, for Ansai soil, rill formation could result in a sharp increase of sediment concentration and erosion amount.%为了明确细沟发育特征及对坡面产流产沙的作用,该文在固定坡度(10°)和2个雨强(1.5和2 mm/min)条件下,采用室内纯净水模拟降雨试验的方法,研究了(壤)土和黄绵土的坡面细沟发育过程和水沙关系.研究结果表明,细沟主要由沿坡面方向呈线状平行分布的跌坎链相互连通演化而成,在雨强较小时壤土更易形成细沟,而黄绵土在雨强较大时才能形成细沟.含沙量与侵蚀速率的变化规律与坡面跌坎和细沟的形成具有同步关系,雨强的增大不会引起壤土含沙量和侵蚀速率的明显增加,但对黄绵土含沙量和侵蚀速率的变化有很大影响,在大雨强时黄绵土含沙量和侵蚀速率会迅速增加,并在坡面细沟形成后很快填平过(壤)土.同时,细沟的存在并不会引起(填)土含沙量和侵蚀速率的明显变化,但黄绵土对坡面细沟反应敏感,细沟一旦形成会导致其含沙量和侵蚀量的急剧增加.该研究为坡耕地细沟侵蚀的有效防治提供相应的理论指导.