Abstract
• Differences in the amount of soil loss under different soil textures . • Analysis of the degree of soil loss under different microtopography . • The amount of sedimentation in the downstream gully head is related to topographic factors. • Soil loss is influenced by the sand content and soil bulk density of the soil. Gully head erosion is one of the most important types of erosion on the Loess Plateau, but little is known about its relationship with microtopography. The purpose of this study was to evaluate microtopographic effects on the process of gully erosion, the rate of gully retreat and gully morphology using different gully head heights. A series of scour tests (flow discharges were 2, 4 and 6 l min −1 ) were conducted indoors, and the amount of soil lost increased with both the rate of gully retreat and the initial gully head height. Compared to silty soils (S), sandy soils (N) showed higher soil losses, but also higher sediment reduction benefits. In addition, a principal component analysis was used to examine the relationships among topographic factors and to classify the degree of erosion into three categories. The four topographic factors (amplitude, roughness, surface incision and slope) were closely correlated, and all were negatively correlated (P < 0.01) with the amount of downstream bed sedimentation. Thus, the topographic parameters of the gully channel, under gully head erosion, reflected the degree of upstream soil loss and downstream bed deposition. These factors were used to calculate the sediment reduction benefit under gully head erosion and may serve as a reference for soil and water conservation measures on the Loess Plateau.
Published Version
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