Response Relationship between Microtopographic Variation and Slope Erosion under Sand-Cover

Feichao Wang,Lin Li,Guoce Xu,Jianwen Zhang,Peng Li,Zhanbin Li,Yuting Cheng

doi:10.3390/w11122488

Abstract

Slope microtopography is an important factor that affects the process of slope erosion. We quantified the responses between microtopography and the amount of erosion on overland sand slope and loess slopes through an indoor artificial simulated rainfall experiment. Three continuous rainfall tests under 1.5 mm/min rain intensity were used to analyze the spatial variation of slope microtopography and soil erosion with three-dimensional laser scanning technology. Our results show that under 0.5, 1.0, and 1.5 cm sand-covered slopes, the runoff time of the first rainfall is delayed by 18, 19, and 23 min, respectively, compared with the loess slope. Furthermore, the average sediment concentration on the slope decreased with subsequent rainfall events. The total erosion of the slope under 0.5, 1.0, and 1.5 cm sand was 4.24, 3.57, and 5.40 times that of the loess slope, respectively. The erosion of the sand-covered slopes was much larger than that of the loess slope. The length of the main sand production area was about 2.4 times that of the loess slope and the peaks of the erosion amount of the slope were mostly distributed in the lower part of the slope. As the rainfall progressed, the microtopographic factors of the loess slopes increased significantly (p < 0.05), and the microtopographic factors of the sand slopes increased, but not significantly (p > 0.05). We found that the microtopographic factors with the strongest erosion responses to the loess slope and the sand-covered slope were surface incision and surface roughness. The response relationship between microtopographic variation and erosion of the loess slope was stronger than the sand-covered slope, and suggests that other, unaccounted-for factors may be affecting the erosion of sand-covered slopes. This study provides a reference for erosion mechanisms of the wind–water erosion crisscross region.

Highlights

Microtopography is a ground morphological feature formed by raindrops, surface runoff, and human cultivation that has large effects on surface runoff and erosion processes
We found that the loess slope roughness increased with rainfall events (Figure 5A)
In addition to studying the response relationship between the change of microtopographic factors and the amount of erosion, we considered the influence of hydrodynamic factors of the upper water on erosion by measuring the flow velocity of each section of the slope

Summary

Introduction

Microtopography is a ground morphological feature formed by raindrops, surface runoff, and human cultivation that has large effects on surface runoff and erosion processes. Soil microtopography affects the occurrence and evolution of soil erosion through changes in elevation that alter water flow direction and hydraulic characteristics [1,2]. Water 2019, 11, 2488 shown to change both sediment yield and microtopography during the erosion process [17]. Surface roughness variation has been shown to be a good predictor of erosion, at least on horizontal ridge slopes [23,24,25,26]. Using traditional microtopographic measurement methods, Jester et al (2005) [27]

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Methods

Discussion

Conclusion