Impact of grass belt position on the hydraulic properties of runoff in gully beds in the Yuanmou Dry-hot valley region of Southwest China

摘要

Gully erosion is one of the major contributors to severe land degradation in the Yuanmou Dry-hot valley region of Southwest China. Planting vegetation in gully beds has proven to be an effective measure in controlling the development of gullies. However, the inner mechanism for this process remains unclear. In this paper, in situ scouring experiments were performed to reveal the influence of grass belt position on the hydraulic properties of runoff in gully beds. The results demonstrate that (1) grass belt position can have a significant effect on reducing runoff erosivity (runoff shear stress, stream power) and sediment content in gully beds, and that the reduction may be strengthened as the distance between the gully headwall and grass belt (DHG) decreases; (2) grass belts could play a positive role in enhancing the surface resistance and increasing flow energy consumption, as resistance and flow energy consumption increase as DHG increases; and (3) there were similar trends in the temporal variations within the hydraulic properties, which changed sharply in the early stage of the experiment and then tended to stabilize, with their time to stability continuously increasing as DHG decreased.