Effects of vegetation spatial pattern on erosion and sediment particle sorting in the loess convex hillslope

Abstract

To address the problem of serious soil erosion on the Loess Plateau, under the conditions of limited vegetation measures, the runoff erosion characteristics and erosion sediment sorting characteristics of vegetation at different positions on the upper slope of convex hillslopes are investigated, and the optimal vegetation spatial pattern is proposed according to the benefits of water storage and sediment reduction at different vegetation positions. The fluctuation degree of flow discharge per unit area of different vegetation spatial patterns is small, and the variation process of sediment discharge per unit area of each vegetation spatial pattern fluctuated sharply with the increase of runoff time. After planting vegetation on the slope, the total runoff yield and sediment yield were reduced. The runoff yield reduction benefit was 19.65% when the grass belt was 6 m away from the slope top; and the sediment yield reduction benefit was more than 70% when the grass belt was 2 m away from the slope top. Under the condition of hydraulic erosion on the slope covered with vegetation, the erosion particles are mainly fine particles, with high silt content and relatively small sand content. The farther the vegetation is arranged from the slope top, the more easily silt of size 0.002–0.05 mm is eroded. The higher effectiveness in terms of reductions of both runoff and sediment yields were obtained when the vegetation is planted in the proximity of the end of the length of the slope.

Vegetation patterns affect soil aggregate loss during water erosion

“…Pattern D exhibits the largest reductions in runoff and sediment. This result is consistent with the reports of Su et al (2022) and Bai et al (2022) based on which vegetation planted on a slope effectively reduces the runoff and sediment.…”

Synergistic effects of vegetation restoration and check dams on water erosion in a slope‐gully system

“…During water erosion, splashing raindrops and runoff scouring are the main energy sources (Su et al, 2022). Vegetation intercepts rainfall through the canopy, thereby reducing the energy of the raindrops (Kervroëdan et al, 2021).…”

“…Four main mechanisms underlying the control of soil and water loss by vegetation restoration have been suggested: (1) vegetation mechanically intercepts rainfall through its multi‐level aboveground parts (i.e., forest canopy), which reduces the energy of splashing raindrops and runoff yield (Kervroëdan et al, 2021); (2) vegetation reduces runoff yields because litter absorbs some water and the soil water infiltration capacity is increased (Han et al, 2021; Zhou et al, 2016); (3) vegetation roughens the slope surface, increases the flow resistance, and reduces the flow velocity (Zhang et al, 2018); and (4) vegetation roots promote soil aggregate formation, which improves the soil stability and reduces sediment loss (Hou et al, 2020). The pattern of the vegetation is important for the control of runoff and sediment yields (Bartley et al, 2006; Bautista et al, 2007; Shi et al, 2022; Su et al, 2022; Zhang et al, 2018). Bartley et al (2006) reported that the presence of vegetation near an outlet had better effects on reducing runoff and sediment loss than bare patches of soil.…”

“…Runoff transports sediment from the slope surface to the gully in a continuous, dynamic process. Previous studies of vegetation and check dams have focused on the effects of water and sediment reductions caused by a single measure (Shi et al, 2022; Su et al, 2022; Tang et al, 2019; Y. Xu et al, 2013; Yuan et al, 2022; Zhang et al, 2018). Furthermore, it was not previously clear how to quantitatively assess the synergistic effects of both measures.…”

“…Moreover, the dams currently retain a total of 28 Â 10 9 t of water and soil. Guo sediment reductions caused by a single measure (Shi et al, 2022;Su et al, 2022;Tang et al, 2019;Y. Xu et al, 2013;Yuan et al, 2022;Zhang et al, 2018).…”