Loess landslides identification and analysis of deformation mechanism in Heifangtai, China

Document Type

Article

Publication Date

1-1-2026

Abstract

Landslides induced by long-term agricultural irrigation are widespread on the Heifangtai loess terrace in Gansu Province, northwestern China. Early identification of active and potentially reactivated loess landslides, together with an explanation of their deformation mechanisms, is essential for hazard assessment and mitigation. This study integrates high-resolution optical interpretation, small baseline subset interferometric synthetic aperture radar (SBAS-InSAR), and unmanned aerial vehicle (UAV)-derived geomorphic evidence to investigate the spatial distribution, deformation evolution, and failure modes of representative irrigation-induced loess landslides. Optical images were used to delineate landslide boundaries, rear scarps, tension cracks, damp zones, and toe fissures, whereas 192 Sentinel-1A ascending scenes from October 2014 to June 2023 were processed to derive long-term deformation fields and time-series displacement curves. Three representative landslides, DC#2, JJ#4, and CJ#8, were selected because they are located in different active landslide clusters, have documented failure histories, and show clear optical, UAV, and InSAR evidence of deformation. The results indicate that: (i) diagnostic geomorphic features identified from optical imagery provide effective spatial constraints for interpreting InSAR point targets; (ii) representative active landslides show marked spatiotemporal heterogeneity, with line of sight (LOS) deformation velocities generally ranging from approximately − 15 to − 50 mm/yr, indicating slow-moving deformation or active creep rather than instantaneous rapid motion captured by InSAR; and (iii) the dominant deformation mechanism is the rise in groundwater levels caused by long-term irrigation, while freeze–thaw cycles and rainfall infiltration act as important short-term accelerators. Cross-validation using optical interpretation, UAV orthophotos, historical landslide records, and published GPS/GNSS, crack gauge, and field evidence supports the general reliability of the detected deformation patterns. Although single-viewing-geometry InSAR cannot fully resolve three-dimensional displacement, its combination with optical and UAV-derived evidence provides a practical framework for regional-scale identification and monitoring of irrigation-affected loess landslides.

Publication Title

Landslides

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