Delayed slope response to infrastructure-induced landscape modifications in mountainous terrain revealed by high-resolution LiDAR analysis

Large-scale infrastructure development in mountain regions produces significant changes in slope morphology and surface processes. However, stability assessments conducted after construction often rely on static or short-duration evaluations. These approaches tend to assume an immediate geomorphic adjustment to human disturbance, which can overlook delayed and nonlinear responses of hillslopes. This study examines terrain adjustments that occur with a time delay following major construction activities in complex mountainous settings. The analysis is based on a series of high-resolution topographic datasets obtained through repeated LiDAR surveys along the Sibiu - Pitești motorway corridor in the Southern Carpathians of Romania. Changes in terrain configuration caused by excavation, filling, drainage alteration, and the unloading of slopes are identified by comparing elevation models and terrain metrics. Instead of focusing solely on deformation located at the site of intervention, the study investigates terrain responses that appear later and in areas situated upslope or laterally from the engineered zones. Findings show that slope instability and surface reorganization often emerge after a measurable time delay, typically reactivating existing geomorphic features such as drainage pathways, slope breaks, and erosional forms. These responses are not random but show a strong dependence on prior landscape conditions and the type of construction-related disturbance. The results emphasize the limitations of early assessments performed shortly after construction, which may fail to capture landscape dynamics relevant for landslide initiation. The study demonstrates the usefulness of repeated LiDAR mapping for detecting evolving terrain responses in engineered mountain landscapes and supports the integration of time-sensitive processes into hazard assessment strategies.