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Title: Spatial heterogeneity of surface roughness during different erosive stages of tilled loess slopes under a rainfall intensity of 1.5 mm min-1

Author
item ZHANG, Q - Northwest Agricultural University
item WANG, J - Northwest Agricultural University
item ZHAO, L - Northwest Agricultural University
item WU, F - Northwest Agricultural University
item ZHANG, Z - Northwest Agricultural University
item Torbert, Henry - Allen

Submitted to: Soil and Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/25/2015
Publication Date: 6/8/2015
Citation: Zhang, Q.J., Wang, J., Zhao, L., Wu, F., Zhang, Z., Torbert III, H.A. 2015. Spatial heterogeneity of surface roughness during different erosive stages of tilled loess slopes under a rainfall intensity of 1.5 mm min-1. Soil and Tillage Research. 153:95–103.

Interpretive Summary: Studies about its spatial heterogeneity of surface roughness has been one of the most important problems in the field of soil erosion. The objective of this study was to understand the spatial heterogeneity of surface roughness of 4 typically loess tilled sloping surfaces during different erosive stages in the Chinese Loess Plateau. These stages included before rain, splash erosion, sheet erosion and rill erosion. The study was conducted under a rainfall intensity of 2.0 mm'min-1 with tillage treatments of artificial backhoe, artificial digging, contour tillage and linear slope. Results reveal not only the coupling relationship between spatial heterogeneity of microtopography and erosion, but also lay a theoretical foundation to guide future tillage practices in sloped areas of the Loess Plateau.

Technical Abstract: The loess tilled slope is the main place for soil erosion in Chinese Loess Plateau, and studies about its spatial heterogeneity (SH) of surface roughness (SR) has been one of the most important problems in the field of soil erosion. The objective of this study was to reveal the SH of SR of 4 typically loess tilled sloping surfaces during different erosive stages: (before rain (BR), splash erosion (SpE), sheet erosion (ShE) and rill erosion (RE)) under a rainfall intensity of 2.0 mm'min-1. Soil surface elevation data points were taken and analyzed with both the semivariogram function and fractal dimension models. Results show that: 1) the SH of SR has a multi-scale variability of all four tilled sloping surfaces: artificial backhoe (AB), artificial digging (AD), contour tillage (CT) and linear slope (CK), the same tilled sloping surface has similar spatial variability in different erosive stages. 2) the rainfall had a certain reducing, enhancement and reducing effect on SR during the development of erosion from SpE, ShE to RE stages separately, and the SH of SR decreases with the increasing slope gradient. However, effects of tillage practices and slope gradient on spatial autocorrelation were far larger than the influence of rainfall 3) The overall autocorrelation scale of SR should be 3.15 m, although it is different under various tillage practices or slope gradients. 4) the SR presents a certain anisotropy during the slope direction of 10° and 22.5°, while it presents isotropy or weaker anisotropy on the others. 5) The fractal dimension of the SR at various erosion stages ranged from 1.59 to 1.85, which shows that the SR has good fractal features. The results of segmentation analysis can reflect the SH of SR at diverse scales. It can also reflect the entire SH of different erosion processes better than can a single fractal dimension. In this paper, we not only reveal the coupling relationship between SR of microtopography and erosion, but also lay a theoretical foundation to guide future tillage practices in sloped areas of the Loess Plateau.