Size distribution of loess slides in relation to local slope height within different slope morphologies

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Loess slides are widespread and dangerous gravity-induced surface processes on the Loess Plateau of north-central China. The local slope height and slope morphology have been considered as important conditioning factors for landslide susceptibility mapping. However, the quantitative relationship between landslide size and local slope height within different slope morphologies is not very clear. In this study, an inventory of 155 loess slides was developed based on detailed field investigation and remote sensing image interpretation. Statistical analysis and GIS were applied to find the quantitative relationships between the size of these loess slides and local slope height in different types of slope morphologies. The analysis shows that the relationship between the loess slides volume and area exhibits a similar trend within different types of slope morphologies. In addition, the analysis demonstrated that loess slides are more frequent on local slope height from 40 to 100m. Stepped slopes with higher pore water pressure are prone to sliding, and approximate 34.19% of total loess slides occur in these stepped slopes. Moreover, the analysis shows that the mean loess slide area and volume rapidly increase with increasing local slope height. Furthermore, the result underlines the fact that both the local slope height and the slope morphology are two fundamental factors that control the occurrence as well as size distribution of loess slides. The loess slide size remarkably increases with increasing local slope height within every type of slope morphologies. These findings indicate that local slope height can limit the loess slide size and their spatial extent. Moreover, we quantified the correlation between the loess slide size and local slope height using power law form, and the scaling exponents of the correlations are different within different slope morphologies.