SBAS-InSAR for sustainable development goals (SDGs)—the impact of extreme precipitation on the foothill's stability of the South Taihang Mountains, China

The ‘7·20’ extreme rainfall event in Henan Province challenged regional geological safety. While urban flooding has been well studied, the mechanisms of surface deformation induced by extreme rainfall in the alluvial geological structures of foothill plains remain unclear. Fifty-two Sentinel-1A images acquired from 2020 to 2021 were selected to derive surface deformation values of the South Taihang Mountains foothills using the SBAS-InSAR technique. The Mann‒Kendall test was employed to detect deformation anomalies associated with rainfall and quantify differential impacts on distinct geological units and critical water-infrastructure systems. Study findings: (1) The region is generally stable (88.9% of the pixels show deformation rates between −10 and 10 mm/yr), though some typical structures demonstrate significant deformation. (2) Deformation at key water conservancy projects, such as the Xiaolangdi Dam, is influenced by rainfall and exhibits a phased cycle with an overall intensifying trend. (3) Heavy rainfall replenished surface aquifers and caused waterlogging of farmland in the high-water coal‒grain composite zone. (4) There are obvious differences in deformation along the middle route of the South-to-North Water Diversion Project (MRP), which arises from different geological types. This study evaluates ground deformation and foundation instability caused by heavy precipitation, guiding urban disaster mitigation, hydraulic-facility hazard checks, and agricultural risk assessment.