Inhibiting Effects of Vegetation on the Characteristics of Runoff and Sediment Yield on Riparian Slope along the Lower Yellow River

Abstract

Riparian vegetation plays a vital role in soil and water conservation and river health maintenance. However, its inhibiting effects on water and soil loss are limited by different factors, such as slope gradient, vegetation coverage and their interaction. Therefore, this study quantified the inhibiting effect of riparian vegetation on the runoff, sediment and hydraulic characteristics of overland flow, and assessed its relative contribution to slope gradient. Specifically, we selected a riparian slope along the lower Yellow River as a case, and used a field-simulated rainfall experiment under specific rainfall intensity (90 mm/h), different vegetation coverage (0%, 15% and 30%) and slope gradients (5°, 10°, 15° and 20°). The results showed that the presence of vegetation can reduce the slope runoff rate and erosion rate. However, greater slope gradients can result in a lowering of the inhibiting effects of riparian vegetation on sediment yield. There was a critical value of vegetation coverage for inhibiting eroded sediments which was influenced by the degree of slope gradient. At 15% vegetation coverage, vegetation inhibited the slope sediment yield greatly at a slope gradient of less than 8°; while at 30% vegetation coverage, vegetation greatly inhibited the slope sediment yield at slope gradients <11°. Hydraulic characteristics were closely related to the slope gradient and vegetation coverage by the power function. Grey correlation analysis revealed that, with increasing of vegetation coverage, the effect of stream power on slope sediment yield decreased, while the effect of the friction coefficient on slope sediment yield increased. In summary, riparian vegetation can effectively inhibit slope runoff and sediment yield, but its inhibiting effect is notably affected by slope gradient.

Runoff, Sediment Loss and the Attenuating Effectiveness of Vegetation Parameters in the Rainforest Zone of Southeastern Nigeria

“…Additionally, it is a rainwater-absorbing reservoir. This assertion is consistent with that of [38][39][40], who identified tree size, vegetation cover and tree density as the essential plant component influencing water-holding capacity for minimizing soil nutrient leaching. The positive link between girth and sediment loss on the 5-year-old fallow is not unexpected since the bushes' girth was not sufficiently established to function as a physical barrier against precipitation.…”

“…This agrees with the findings of [37] that vegetation regulates hydrological processes significantly. Moreover, Wu et al [11,38] noted that the presence and growth of vegetation attributes decreases runoff and sediment loss. Similarly, Wu et al [11] and Iwara [4] stated that crown cover lessens the negative influence of rainfall on the land and soil by intercepting and holding a significant amount of their energy.…”

Effects of ryegrass canopy and roots on the distribution characteristics of eroded sediment particles during heavy rainfall events on steep loess‐cinnamon slopes in Zhangjiakou, China

“…There were two primary causes for this variation: the reduction in raindrop kinetic energy associated with the increase in coverage density and the increase in runoff resistance due to the higher coverage density of vegetation. Zhang et al (2019) also reported similar results. Nevertheless, Zhu et al (2010) found that the runoff and erosion rates decreased with increasing coverage density when the coverage density was lower than 60%; conversely, the runoff and erosion rates exhibited increasing trends.…”

Quality Profile of Riparian Zone and Vegetation Quality in Amprong River, Tumpang District Based on QBR index and NDVI

“…High vegetation connectivity helped maintain river water quality. Vegetation around riverbanks helped remediate pollutants carried by water runoff, and other water flows entering the river [15,16]. If there was little vegetation, the pollutant residue could not be remedied, resulting in water and soil pollution.…”