## 1 Introduction
[30] found that rising groundwater levels can destabilize loess slopes, they did not delve deeply into the progressive development process of retrogressive landslides. Retrogressive landslides typically begin with large-scale flowslides, followed by secondary slides and falls. Over time, the stability of the slope gradually decreases. Research by [PERSON] et al. [4] has shown that retrogressive landslides involve multiple consecutive failure events, and soil physical properties along with groundwater fluctuations are key factors driving their progression. [PERSON] et al. simulated retrogressive landslides through large-scale model testing, revealing that crack development progresses through four stages and identifying key failure mechanisms, which provide valuable insights into monitoring and understanding landslide behavior [39]. Additionally, the long-term effects of irrigation on groundwater levels exacerbate the frequency and severity of landslides. Continued irrigation raises the groundwater level, further weakening the slope's stability [40; 41]. Overall, although there has been some progress in the study of retrogressive landslides, the unique soil characteristics, groundwater fluctuations, and irrigation practices in loess regions still need to be more thoroughly explored. This is crucial for improving the prediction and mitigation of landslides in the Loess Plateau. Based on the aforementioned research on retrogressive landslides in clayey soils, this study offers a comprehensive analysis of the triggering mechanisms and evolutionary characteristics of retrogressive landslides in loess regions. This study advances the understanding of retrogressive landslides in loess regions by systematically investigating the following key aspects through the use of the following research methods: (1) Field Geological Investigation: Geological surveys were conducted on the loess slopes of the South Jingyang Platform, recording the temporal and spatial distribution characteristics of landslides. (2) Satellite Monitoring and GIS Mapping: High-resolution satellite imagery and GIS tools were used to monitor and map the spatial distribution of landslides. (3) Unsaturated Soil Mechanics Analysis: This method analyzes the impact of groundwater fluctuations and changes in irrigation practices on the stability of loess slopes, aiming to uncover the failure mechanisms behind retrogressive landslides. (4) Failure Mechanism Analysis: Based on the field investigation and the research data obtained, a physical model of the gradual evolution of retrogressive landslides was proposed, analyzing the failure mechanisms of retrogressive loess landslides. (5) Landslide Risk Assessment and Future Trends: Building upon a detailed analysis of the retrogressive landslides and their influencing factors, this study discusses potential strategies for reducing landslide risks in the future, providing preliminary insights into the likely evolution of landslide frequency and slope stability based on ongoing changes in groundwater levels and irrigation practices. In conclusion, this study provides a comprehensive framework for understanding the dynamics of retrogressive landslides in loess regions, integrating field investigations, satellite monitoring, soil mechanics analysis, and failure mechanism modeling. The findings contribute to a deeper understanding of how groundwater fluctuations, irrigation practices, and structural factors interact to trigger these landslides. By offering insights into the evolution and failure mechanisms, this research lays the foundation for developing effective risk mitigation strategies and early warning systems, which are essential for managing and reducing landslide hazards in the future.