为了探究次降雨条件下坡度对黄土坡面侵蚀及水沙关系的影响,在室内进行模拟降雨试验,结合能量理论对黄土坡面水沙关系进行了研究。结果 表明:(1)在次降雨条件下,坡面产沙强度随产流时间的变化趋势较产流强度更为复杂,并且两者随着产流时间的变化趋势存在不同步性;(2)坡面总产流量与总产沙量随坡度的变化均呈二次函数关系,并且在20°～25°存在量变的临界值;(3)坡面产流强度与产沙强度呈正相关关系,方程系数a随坡度呈现增大后减小的趋势;(4)累积产流量与累积产沙量之间呈正相关关系,相关系数c的绝对值与坡度成正比;(5)坡面平均径流能量随坡度的变化呈上升—下降的趋势,在坡面侵蚀过程中,平均径流能量与平均产沙强度之间的关系可用线性方程描述,两者呈正相关关系,平均径流能量可以合理预测黄土坡面的输沙能力。该研究可为完善黄土区的土壤侵蚀机理提供理论依据。
In order to explore the effect of slope gradient on erosion and water-sediment relationship on the loess slope under a rainfall event, simulated rainfall experiments were carried out in the laboratory, and the water-sediment relationship on the loess slope was studied with energy theory. The results show that:(1)under the condition of a rainfall event, the trend of sediment yield intensity on slope over runoff yield time is more complex than that of runoff yield intensity, and there is the asynchrony between the two trends over the runoff yield time;(2)the relationship between total runoff and sediment yield can be described by quadratic, and there is a critical value of quantitative change between the gradients ranging from 20° to 25°;(3)there is a positive correlation between runoff intensity and sediment yield intensity, and the coefficient of equation decreases with the increase of slope gradient;(4)there is a positive correlation between cumulative runoff and sediment yield, and the absolute value of correlation coefficient is proportional to slope gradient;(5)the average runoff energy increases or decreases with the change of slope gradient; in the process of slope erosion, the relationship between average runoff energy and average sediment yield intensity is positively correlated, and can be described by linear equation; the average runoff energy can reasonably predict the sediment transport capacity of Loess slope. These results can provide the theoretical basis for understanding the mechanism of soil erosion in Loess area.
