Effects of Slope Gradient and Rainfall Intensity on Sediment Yield in the Colluvial Deposits of Southern Guangxi Under Simulated Rainfall

Abstract

[Objective] To reveal the influences of slope gradient and rainfall intensity on the erosion and sediment yield characteristics of the colluvial deposits from Benggang, and to provide a scientific basis for soil and water loss prediction and control of the colluvial deposits in southern Guangxi. [Methods] The indoor experiment of simulated rainfall was carried out to investigate the erosion and sediment yield phocesses of colluvium slope under different slope gradients (15°, 20°, 25°) and rainfall intensities (60, 90, 120 mm/h). [Results] The results showed that the variation processes of the erosion rate of the colluvium were relatively stable, and the erosion rate was mostly lower than 5.0 g/(m2·s), and showed a certain downward trend when the rainfall intensity was 60 mm/h under different slope conditions. While, the erosion rate fluctuated to increase first, and then decreased under the rainfall intensity of 90 to 120 mm/h. The maximum erosion rate during each rainfall increased with the increase of rainfall intensity and slope gradient, and the maximum erosion rate occurred within 0 to 25 min and tended to advance with the increase of slope gradient. The sediment yield amount (from 3.64 to 48.07 kg/m2) increased with the increase of rainfall intensity and slope gradient, and the nonlinear regression result (a power function) between the sediment yield amount and rainfall intensity and slope gradient was better than the linear regression result. The correlation between sediment yield amount and the interaction of slope gradient and rainfall intensity was the most significant and showed a high-significant linear function relationship. [Conclusion] The sensitivity coefficient of the sediment yield amount to rainfall intensity was higher than that to slope gradient, and the influence of rainfall intensity on sediment yield was stronger than slope gradient. gradient Slope drainage measures should be taken in the prevention and control of colluvial deposit erosion.

Keywords

• rainfall simulation
• colluvial deposits
• slope gradient
• rainfall intensity
• soil erosion rate