聚丙烯酰胺(PAM)对三峡库区紫色土坡面片蚀的影响

设置不同PAM施加量(0,0.4,0.8,1.6 g/m²),在不同坡度(15°,20°,25°)条件下开展不同雨强(60,90,120 mm/h)的模拟降雨试验。研究不同PAM施加量紫色土坡面片蚀产流产沙过程及其对产流产沙量的影响程度和主要因素,并分析了PAM对坡面片蚀可蚀性的影响。结果表明:坡面产流过程呈现先持续增加后趋于波动稳定的变化趋势,产沙过程则呈现先迅速减少并趋于稳定的变化趋势,PAM对片蚀的产流产沙过程变化趋势没有影响。和空白对照组相比,PAM施加量为0.4,0.8,1.6 g/m²的产流总量平均分别减小7.71%,35.16%,21.12%,产沙总量平均分别减小35.80%,49.39%,17.85%,PAM施加量为0.8 g/m²时产流总量和产沙总量最小。同种雨强下,不同施加量减流效益的大小顺序为0.8 g/m²>1.6 g/m²>0.4 g/m²,而减沙效益则受到坡度影响,在15°坡面减沙效益大小顺序是0.8 g/m²>1.6 g/m²>0.4 g/m²,在20°和25°坡面减沙效益大小顺序为0.8 g/m²>0.4 g/m²>1.6 g/m²。施加PAM能有效降低片蚀可蚀性,与空白对照组相比,施加PAM后降低效果依次为0.8 g/m²>0.4 g/m²>1.6 g/m²,片蚀可蚀性依次降低54.40%,40.94%,18.21%。

Influence of Polyacrylamide (PAM) on the Sheet Erosion Process of Purple Soil in Three Gorges Reservoir Area

The simulated rainfall experiments were conducted under different slopes (15°, 20° and 25°) combined with different Polyacrylamide (PAM) application rates (0, 0.4, 0.8 and 1.6 g/m²) and different rainfall intensities (60, 90 and 120 mm/h) in this research. The process of runoff and erosion for the sheet erosion of purple soil slopes under different PAM application rates, the influence degree of PAM on the erosion and runoff and their main influence factors were analyzed. Also, the interrill soil erodibility under different PAM application rates was also evaluated. The results showed that the processes of runoff rate and erosion rate increased at first and then was stable with fluctuation, and decreased rapidly at first and was stable with fluctuation, respectively. PAM did not affect the runoff and erosion process of sheet erosion. The runoff amount and erosion amount decreased by 7.71%, 35.16% and 21.12% and by 35.80%, 49.39% and 17.85% for the PAM application rate of 0.4, 0.8 and 1.6 g/m², respectively, when compared with the no PAM application condition. The runoff reduction benefits of different PAM application rates followed the sequence of 0.8 g/m² > 1.6 g/m² > 0.4 g/m² for different rainfall intensities, while the sediment reduction benefits were affected by the slope. On the 15° slope, the order of magnitude of sediment reduction benefit of PAM application was 0.8 g/m² > 1.6 g/m² > 0.4 g/m², while the order of magnitude was 0.8 g/m² > 0.4 g/m² > 1.6 g/m² on the 20° and 25° slopes. The application of PAM could effectively reduce the interrill soil erodibility. The order of magnitude of the effect was 0.8 g/m² > 0.4 g/m² > 1.6 g/m², which was reduced by 54.40%, 40.94% and 18.21%, respectively, when compared with the no PAM application condition.