Response of soil detachment capacity to landscape positions in hilly and gully regions of the Loess Plateau

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Landscape position may impact soil detachment capacity (Dc) by overland flow through the imposing influences on soil properties and plant roots. Nonetheless, little knowledge existed with regard to the response of Dc to landscape position. Therefore, this study was conducted to detect the response of Dc to landscape positions and identify the primary influencing factors in hilly and gully regions of the Loess Plateau. 540 undisturbed soil samples taken from six landscape positions were subjected to scour in a hydraulic flume to determine Dc. The results demonstrated that Dc of the top ridge was the maximum (1.13 kg m−2 s−1), while Dc of the footslope was the minimum (0.0026 kg m−2 s−1). The landscape positions significantly influenced Dc, presenting a regularly decreasing trend from the top to the bottom. Dc increased with stream power (ω) by a power function. Power function was better than linear function for predicting of Dc. The partial least square regression analysis showed that soil organic matter, water stable aggregate (WSA), root mass density (RMD), and soil cohesion (Coh) dominated the variations in Dc. Significant negative relationships were detected between these primary factors and Dc. Landscape position affected Coh, WSA and RMD, which in turn controlled the regular change of Dc with landscape position. Dc of six landscape positions could be satisfactorily estimated by ω, WSA, and RMD (r2 = 0.81; NSE = 0.81). The results are helpful to understand the vertical changes in soil erosion intensity in small watershed scale.