A slope unit is commonly used as calculation unit for regional landslide analysis. However, the capacity of the slope unit to reflect the geomorphological features of actual landslides still needs to be verified. This is because such accurate representation is critical to ensure the physical meaning of results from subsequent landslide stability analysis. This paper presents work conducted on landslides and slope extraction in two areas in China: The Jiangjia Gully area (Yunnan Province) and Fengjie County (Chongqing Municipality). Ground-based light detection and ranging (LiDAR) data are combined with field landslide terrace measurements to allow for the comparison of slope unit extraction methods (conventional vs. MIA-HSU) in terms of their ability to reflect the geomorphological features of shallow and deep-seated landslides. The results indicate that slope unit boundaries extracted by the conventional method do not match the geomorphological variations of actual landslides, and the method is therefore deficient in meaningfully extracting slope units for further landslide analysis. By contrast, slope units obtained using the MIA-HSU method accurately reflects the geomorphological features of both shallow and deep-seated landslides, and thus provides clearer geomorphological meaning and more reasonable calculation units for regional landslide assessment and prediction.

A new detection device was designed by integrating fiber Bragg grating (FBG) and polyvinyl chloride (PVC) tube in order to monitor the slip surface of a landslide. Using this new FBG-based device, a corresponding slope model with a pre-set slip surface was designed, and seven tests with different soil properties were carried out in laboratory conditions. The FBG sensing fibers were fixed on the PVC tube to measure strain distributions of PVC tube at different elevation. Test results indicated that the PVC tube could keep deformation compatible with soil mass. The new device was able to monitor slip surface location before sliding occurrence, and the location of monitored slip surface was about 1–2 cm above the pre-set slip surface, which basically agreed with presupposition results. The monitoring results are expected to be used to pre-estimate landslide volume and provide a beneficial option for evaluating the potential impact of landslides on shipping safety in the Three Gorges area.

The spatial uncertainty of soil mechanical parameters remains a major challenge in physical models for the prediction of rainfall landslides. Currently, the widely adopted stochastic methods for parameter selection disregard the lithological variations and fail to account for rainfall infiltration’s attenuation effects on soil mechanical parameters. Through field sampling and laboratory testing, this study examined the distribution of mechanical parameters across five lithological zones in Fengjie County, Chongqing, China. The soil mechanical parameters at liquid and plastic limits were used as boundaries, and nine attenuation scenarios of mechanical parameters were devised based on disturbance ratios from 0.1 to 0.9, simulating the attenuation effect of rainfall infiltration on parameters. The prediction performance across different attenuation scenarios was then explored. The findings revealed that different lithologies displayed unique normal distribution characteristics. Prediction results from slope units indicate lower disturbance ratios (0.1–0.3) yield ideal miss rates (below 10%) but very high false alarm rates. With higher disturbance ratios (0.4–0.9), missing alarm rates increased while false alarm rates continually decreased. At 0.4 disturbance ratio, both the false and missed alarm rates are optimal. This study recommends setting the disturbance ratio of soil mechanical parameters to 0.4 to achieve a preferable predictive performance in Fengjie County.