Abstract: ObjectiveBenggang is a typical erosion landform in the red-soil hilly region of South China, characterized by strong hydraulic incision, rapid material loss, and high landscape sensitivity. Understanding its surface deformation behavior is crucial for revealing Benggang evolutionary mechanisms and assessing geomorphological stability. However, long-term and continuous monitoring of deformation in Benggang areas remains limited, especially regarding their response to rainfall processes. MethodsTo quantitatively reveal the surface deformation characteristics of typical Benggang areas in Wuhua county, this study utilized 90 Sentinel-1A SAR images acquired from 2022 to 2024. Surface deformation fields were inverted using the Small Baseline Subset Interferometric Synthetic Aperture Radar (SBAS-InSAR) technique, and temporal analysis was conducted in conjunction with synchronous precipitation data. Through high-resolution image interpretation, 390 Benggang units were identified and used for statistical evaluation of deformation magnitude and deformation rate. Results1) The cumulative deformation across the study area ranged from −43 mm to 26 mm, with subsidence center zones showing good spatial consistency with densely distributed Benggang areas. Among the 390 identified Benggang units, approximately 68.4% exhibited net subsidence, with cumulative subsidence mainly ranging from −20 mm to −5 mm. About 22% of the Benggang units experienced cumulative subsidence exceeding −25 mm, indicating significant geomorphic activity. 2) The annual average deformation rate ranged from −16 mm/a to 13 mm/a, with most Benggang areas showing a slow but persistent subsidence trend (−5 to −1 mm/a). Regions with deformation rates exceeding −10 mm/a were primarily located in the northwestern part of the study area, where gully convergence, low terrain, and intense hydrodynamic processes resulted in enhanced instability. 3) Representative monitoring point analysis revealed distinct deformation responses across different geomorphic positions: gully-convergence Benggang showed rapid subsidence immediately after rainfall events, single-slope Benggang exhibited gradual deformation, and slope-toe Benggang displayed pronounced lag effects. Deformation rates showed a significant negative correlation with precipitation (R2=0.69); when monthly rainfall exceeded approximately 200 mm, subsidence rates continuously accelerated, with deformation peaks lagging rainfall peaks by 10–30 days. ConclusionsSBAS-InSAR effectively captured the spatial-temporal deformation dynamics of Benggang landforms in complex red-soil hilly terrain. The deformation magnitude and rate in Benggang areas were significantly higher than those in surrounding non-Benggang zones (t-test, p<0.001), and their deformation processes were strongly modulated by rainfall intensity and timing. The findings validate the applicability of SBAS-InSAR for monitoring Benggang deformation in the red-soil hilly region of South China and provide a scientific basis for Benggang erosion dynamic monitoring and hazard prevention and control.