Influences of sand cover on erosion processes of loess slopes based on rainfall simulation experiments

Abstract

Aeolian-fluvial interplay erosion regions are subject to intense soil erosion and are of particular concern in loess areas of northwestern China. Understanding the composition, distribution, and transport processes of eroded sediments in these regions is of considerable scientific significance for controlling soil erosion. In this study, based on laboratory rainfall simulation experiments, we analyzed rainfall-induced erosion processes on sand-covered loess slopes (SS) with different sand cover patterns (including length and thickness) and uncovered loess slopes (LS) to investigate the influences of sand cover on erosion processes of loess slopes in case regions of aeolian-fluvial erosion. The grain-size curves of eroded sediments were fitted using the Weibull function. Compositions of eroded sediments under different sand cover patterns and rainfall intensities were analyzed to explore sediment transport modes of SS. The influences of sand cover amount and pattern on erosion processes of loess slopes were also discussed. The results show that sand cover on loess slopes influences the proportion of loess erosion and that the compositions of eroded sediments vary between SS and LS. Sand cover on loess slopes transforms silt erosion into sand erosion by reducing splash erosion and changing the rainfall-induced erosion processes. The percentage of eroded sand from SS in the early stage of runoff and sediment generation is always higher than that in the late stage. Sand cover on loess slopes aggravates loess erosion, not only by adding sand as additional eroded sediments but also by increasing the amount of eroded loess, compared with the loess slopes without sand cover. The influence of sand cover pattern on runoff yield and the amount of eroded sediments is larger than that of sand cover amount. Furthermore, given the same sand cover pattern, a thicker sand cover could increase sand erosion while a thinner sand cover could aggravate loess erosion. This difference explains the existence of intense erosion on slopes that are thinly covered with sand in regions where aeolian erosion and fluvial erosion interact.

Sediment load change with erosion processes under simulated rainfall events

“…Several factors e.g. rainfall, slope gradient, slope length, and soil type, may have significant impacts on erosion processes (Sun et al, 2013;Fang et al, 2014;Zhang et al, 2018). For example, Berger et al (2010) indicated that rainfall intensity has greater effects than slope gradient on rill development and sediment load.…”

Combined Impact of Socioeconomic Forces and Policy Implications: Spatial-Temporal Dynamics of the Ecosystem Services Value in Yangtze River Delta, China

“…Meanwhile, technical progress (measured by FDI in this study) showed a remarkable negative relationship with ESV loss. One possible explanation is that the relationship between economic development and ecological environment showed that the two are consistent with the Kuznets curve in an inverted U-shape [87,88]. That is, the natural environment paid a heavy price for economic growth in the early stages of economic development because of backward technology and excessive and disordered mining of resources.…”

Slope Erosion and Hydraulics during Thawing of the Sand-Covered Loess Plateau

“…The Loess Plateau is a sand-covered landform that experiences substantial wind and water erosion [4][5][6]. Due to the differences in physical characteristics, infiltration, hydraulic conductivity, and water holding capacity between the surface sand layer and loess layer, a distinct sand-soil interface is formed between the sand layer and loess layer, and then the typical sand-soil dual structure is formed [7][8][9][10]. Zhang et al [11] found in field rainfall experiments that the runoff and sediment yield processes on the sand-covered slopes are significantly different from those on loess slopes.…”