Modeling the effects of topography and slope gradient of an artificially formed slope on runoff, sediment yield, water and soil loss of sandy soil

Abstract

Due to frequent severe mining activities and globally destructive extreme storms, soil and water loss in open-pit coal mine dumps is extremely serious. To investigate the effect of topography on soil erosion, rainfall with a constant intensity of 1.50 mm·min−1 was conducted on topography models for 60 min. We investigated the effects of 4 topographies (straight slope, concave slope, S-shaped slope and anti-S-shaped slope) and 4 slope gradients (20°, 25°, 30° and 35°) on runoff, sediment yield, and soil and water loss. The results show that the 25° slope gradient was not conducive to infiltration, but the S-shaped slope was favorable. The runoff and sediment yield increased rapidly, then fluctuated upward in a certain range and eventually stabilized with increasing rainfall duration. With increasing slope gradient, the total runoff decreased exponentially, the total sediment yield decreased linearly, and the total amount of water and soil loss declined continuously. The initial runoff time results exhibited the order of anti-S-shaped slope > straight slope > concave slope > S-shaped slope, but the stable runoff size satisfied the S-shaped slope > straight slope > concave slope > anti-S-shaped slope. The results of the significant degree of influence of topography on sediment yield and water and soil loss exhibited the order of anti-S-shaped slope > S-shaped slope > straight slope > concave slope and S-shaped slope > straight slope > concave slope and anti-S-shaped slope. The effect of slope gradient on soil humidity and runoff was more significant than that on topography and their interaction (p < 0.001). Nevertheless, for sediment yield and water and soil loss, topography had the greatest influence (p < 0.001). Notably, the total amount of water and soil loss on the anti-S-shaped slope was relatively minimal.