Active landslide detection using integrated remote sensing technologies for a wide region and multiple stages: A case study in southwestern China.

While significant progress has been achieved in utilizing remote sensing technologies for landslide investigation in China, there remains a notable gap in consolidating information on applicable conditions, application stages, and workflows across various remote sensing methodologies. This paper proposes a comprehensive framework for active landslide detection, incorporating multiple stages and data sources, successfully implemented in a vast region of southwestern China. Furthermore, detailed discussions are provided on the effects of the geometric distortion, land cover type, and various InSAR methods on the accuracy of active landslide identification results. Additionally, the paper delves into the advantages of integrated remote sensing technology in active landslide investigation, encompassing the assessment of current landslide activity status, precise delineation of boundaries, identification of different deformation stages, and determination of damage patterns. Through comprehensive analysis of multisource data, it enhances understanding of the active landslide process, ultimately contributing to the mitigation of casualties and property damage.

Micro-topographic assessment of rill morphology highlights the shortcomings of current protective measures in loess landscapes.

Due to urban expansion and the rapid development of infrastructure in the loess area of China, artificial earth-fill embankments and excavated slopes are increasingly widespread in recent years. Erosion is typical in such loess slopes; however, quantitative statistical analyses of various counter-measures that affects rill erosion are still lacking. Here, we quantified rill morphology and rill erosion development in two newly constructed slopes with different engineering protection measures. We used high-resolution digital surface models (DSMs) acquired using an Unmanned Aerial Vehicle (UAV) to analyze the case areas during two-time periods. Our results from centimeter accuracy differential DSMs demonstrated that rapid rill erosion is prevalent in the study area, expressed as rill density varying between 2.03 km-2 and 8.81 km-2 at different slope surfaces (viz., erosion protected slopes [EPS], landslide protected slopes [LPS], and unprotected slopes [US]). The slope gradient responsible for rill erosion of the EPS, LPS and US are obviously different, and such information is essential for planning preventive measures in each slope type. At the EPS, the severity of erosion is maximum at the top of the ridges, whereas the gap between reinforced concrete lattice and loess deposits are of serious concern at the LPS. The current engineering measures employed in the study area are thus found ineffective for protection against rill erosion. We therefore propose an improved design by implementing an intercepting drain to the existing design for preventing further erosion.