Areas located in gully and hilly regions on the Loess Plateau have topographies with slopes greater than 25° and have the most severe soil erosion. This is the key area for soil and water conservation and ecological restoration undertaken by the National Grain-to-Green Program,
and a large area of steep slope cropland has been converted into grasslands and forests (Xin et al., 2008).
Vegetation restoration effectively strengthened soil erosion control in these gully and hilly regions.
A major influence of slope gradient on soil erosion appears to be exerted through its enhanced effectiveness on lower vegetation cover land.
With slope gradients increased, soil loss has dramatically increased for land uses with lower coverage, especially for woods, moderate and sparse grassland, and cropland (Fig. 7).